ML22143A951

Draft Guidelines Document for Additive Manufacturing - Laser-Directed Energy Deposition

ML22143A951
Person / Time
Issue date:	05/23/2022
From:	Anchondo-Lopez I NRC/NRR/DNRL/NVIB
To:
Anchondo-Lopez I
Shared Package
ML22143A950	List: ML22143A951 ML22143A952
References
Download: ML22143A951 (18)

Text

THE NRC STAFF HAS PREPARED THIS DRAFT DOCUMENT AND IS RELEASING IT TO SUPPORT THE JUNE 2022, PUBLIC MEETING ON ADVANCED MANUFACTURING TECHNOLOGIES. THIS DRAFT DOCUMENT IS SUBJECT TO CHANGE AND ITS CONTENT SHOULD NOT BE INTERPRETED AS OFFICIAL AGENCY POSITIONS. SUBSEQUENT TO THE PUBLIC WEBINAR, THE NRC STAFF PLANS TO CONTINUE WORKING ON THIS DOCUMENT AND COULD INCORPORATE STAKEHOLDER FEEDBACK RECEIVED AT THE PUBLIC WEBINAR.

Draft Guidelines Document for Additive ManufacturingLaser Directed Energy Deposition

1. Introduction and Purpose

When finalized, this draft guidelines document (DGD) will provide U.S. Nuclear Regulatory Commission (NRC) staff with guidelines for conducting reviews of submittals that include components manufactured using additive manufacturinglaser directed energy deposition (L-DED). T hese guidelines are based on the NRC assessment of the impact on component performance of the identified differences between L -DED and traditional manufacturing methods as documented in NRC Technical Assessment of Additive ManufacturingLaser Directed Energy Deposition, (Agencywide Documents Access and Management System (ADAMS)

Accession No. ML21292A188) (hereafter, NRC technical assessment), which builds on the Oak Ridge National Laboratorys (ORNLs) technical information and gap analysis, Review of Advanced Manufacturing Techniques and Qualification Processes for Light Water Reactors Laser Directed Energy Deposition Additive Manufacturing, (ADAMS Accession No. ML21292A187). This document provides L-DED-specific draft guidelines under Subtask 2C, Action Plan for Advanced Manufacturing Technologies (AMTs ), Revision 1, dated June 23, 2020 (ADAMS Accession No. ML19333B973), as a supplement to the AMT generic draft guidelines document, Draft AMT Review Guidelines (ADAMS Accession No. ML21074A037) (hereafter, draft generic guidelines ).

When reviewing an AMT submittal, the NRC staff can refer to the generic guidelines, once finalized, which can assist the NRC staffs review of a submittal requesting the use of an AMT.

The finalized generic guidelines along with this DGD will identify the generic and L-DED-specific information that could be necessary in a submittal in order to provide a timely and efficient review. The NRC technical assessment is also available for additional background and technical information to support the review of a submittal.

2. Brief Description of the NRC Technical Assessment of Laser Directed Energy Deposition

This section describes the purpose of the NRC technical assessment of L-DED, which provides the technical basis for the technical review guidelines described in this DGD. The primary objective of the NRC technical assessment i s to describe the differences between an L-DED-fabricated component and a traditionally manufactured component, assess the impact that the identified difference has on component performance, and identify relev ant technical information pertaining to these differences for L -DED-fabricated components. This DGD is intended to build on the NRC technical assessment and provide guidelines, when finalized, to the NRC staff by identifying important considerations when reviewing a submittal requesting the use of L-DED.

The overall impact to plant safety (e.g., safety significance) is a function of component performance and the specific component application (e.g., its intended safety function). These reports do not address the impact on plant safety, as such an assessment would not be possible without considering a specific component application. In addition to the technical review guidelines in this document, the NRC staff should consider the specific component application and the potential for secondary consequences, such as debris generation and associated impacts,when assessing the impact to overall plant safety.

As discussed in the NRC technical assessment, the NRC s taff identified differences between AMT and traditional manufacturing processes by reviewing the information and gap analysis rankings from the ORNL report, as well as other relevant technical information (e.g., NRC regulatory and research experience, technical meetings and conferences, codes and standards activities, Electric Power Research Institute and U.S. Department of Energy products and activities).

3. NRC Generic Guidelines for Advanced Manufacturing Technologies and Laser Directed Energy Deposition -Specific Guidelines

The finalized generic guidelines will identify the information that could be necessary in a submittal to ensure a timely and efficient review. Appendix A to the generic guidelines identifies the five primary topics to be addressed in a submittal:

(1) Quality Assurance (QA): p rocess followed during the manufacture and implementation of AMTs to ensure adherence to QA requirements (e.g., Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Domestic licensing of p roduction and u tilization facilities, Appendix B, Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants), established methods (e.g., commercial -grade dedication), or both (2) Process Qualification: steps taken to demonstrate that the component will be produced with characteristics that will meet the intended design requirements (3) Supplemental Testing: testing conducted to demonstrate that those material and component properties required to meet the design requirements are acceptable in the applicable service environmental conditions, and thus the performance of the component in service will be acceptable (4) Production Process Control and Verification: steps taken to ensure that each component will be produced in accordance with the qualified process and, if the production process fails to meet the qualification essential variables, the steps taken to reestablish the qualified process (5) Performance Monitoring: actions taken to provide assurance that the component will continue to meet its design requirements until the end of its intended service life

Table 1 includes the identified differences between L-DED and traditional manufacturing outlined in the NRC technical assessment (both generic and 316L material-specific ) and identifies those primary elements from Appendix A to the g eneric guidelines that are expected to be most commonly applicable to each of the differences. However, the applicable primary elements may vary on a case-by -case basis, depending on the licensees approach to demonstrating quality and safety. Therefore, this table provides an example of applicable elements and reflects that n ot every element in Appendix A to the generic guidelines is applicable to every difference listed in Table 1.

QA comprises all those planned and systematic actions necessary to provide adequate confidence that a system or component will perform satisfactorily in service. QA processes implemented during the manufacture and implementation of AMTs ensure that QA requi rements (e.g., 10 CFR Part 50, Appendix B), established methods (e.g., commercial-grade dedication),

or both, have been satisfied. For AMTs, a QA program will specifically address novel or unique aspects of manufacturing or implementation specific to the AMT. Therefore, Table 1 does not explicitly include QA as a distinct column, but QA is applicable to each of the differences between traditional manufacturing and L-DED processes identified in the table and achieved through successful performance of the other four Appendix A items: process q ualification, supplemental testing, production process c ontrol and v erification, and p erformance monitoring.

Tables 2A and 2B provide the technical review guidelines. Table 2A lists the generic differences between traditional manufacturing and L-DED. Table 2B lists the material-specific differences between traditional manufacturing and L-DED 316L stainless steel. 316L is the alloy relevant to L-DED-fabricated nuclear applications with the most information currently available in the open literature. While Table 2B is also based on the available information in the open literature for 316L, the differences identified in Table 2B involving material -specific properties and performance would need to be considered for any new ly fabricated material using L-DED.

In general, material-specific data for the proposed processing and post-processing parameters are important for any nuclear L-DED-fabricated component to ensure adequate component performance in the applicable environment, including properties (e.g., fracture toughness, tensile strength) and resistance to aging mechanisms (e.g., thermal aging, irradiation effects, and stress corrosion cracking (SCC)). It is important to note that the feedstock (i.e., powder vs.

wire) may impact the differences listed in the tables. The impact thatfeedstock selection has on a specific difference is noted as appropriate in Tables 2A and 2B.

Tables 2A and 2B provide technical review guidelines related to the differences for the L-DED process and component performance through the following columns:

• Difference: identifies the differences between L-DED and traditional manufacturing outlined in the NRC technical assessment

• Key Technical Information: summarizes the key technical information documented in the NRC technical assessment for easy reference

• Technical Review Guidelines : provides additional guidelines related to the differences between L-DED and traditional manufacturing that the staff should consider when evaluating how a licensees or applicants submittal addresses the differences between L-DED and traditional manufacturing

It is important to note that a given submittal need not include all elements of these tables.

Table 1. Relevant Elements from Appendix A to the Generic Guidelines

Difference Process Supplemental Production Process Performance Qualification Testing Control and Verification Monitoring L-DED Machine Process Control X X Powder Feedstock Quality X X Wire Feedstock Quality X X L-DED Build Process Management and Control X X Witness Specimens X X Thermal Post-Processing X X Local Geometry Impacts on Component Properties and Performance X X Heterogeneity and Anisotropy in Properties X X Residual Stress X X Porosity X X Surface Finish X X X Tensile Properties X X Initial Fracture Toughness X X Thermal Aging X X SCC and Corrosion Resistance X X Fatigue X X Irradiation Effects X X High Temperature Time-Dependent Aging Effects (e.g.,

Creep and Creep-Fatigue) X X Weld Integrity X X Weldability / Joining X X

Table 2A. Technical Information and Review GuidelinesL -DED Generic Difference Key Technical Information Technical Review Guidelines

• Contr of L-DED fil is nt Process Qualification ensprocess contr. Im

• The applicant should identify the essential variables related to L-DED machine filcontr casignificantly impact process control and demonstrate that controlling these variables within identified final cpent ties ranges will ensure reliable, adequate, and repeatable component properties and performcft fricio performance.

replicion. Cyrsity,

• At a minimum, the process qualification should consider the following essential databastraclity, maging variables:

stward, s imilar ite o software file preparation (e.g., L-DED software version, and L-DED software L-DED gy important tsing settings)

Machine end-com ity. o calibration of L-DED machine and subsystems (e.g., build stage, feedstock Process

• Machine calibration is vital for deposition, laser optics, atmosphere control)

Control fabrication replication, particularly

• The applicant should identify additional specific essential variables and their ranges ensuring correct feedstock as appropriate.

deposition parameters, laser Production Process Control and Verification power, laser spot size, travel

• During production, the applicant should demonstrate that process control and speed, and atmospheric quality verification will maintain the production process within the qualified essential control in addition to geometric variable ranges.

tolerances. For LP-DED, this

• The applicant can use a variety of machine process controls approaches to includes contamination demonstrate process control and verification, including, but not limited to periodic minimization if recycling powder. machine calibration verification.

• Dle powder cractizion Process Qualification contr, p renting powr

• Through process qualification, the applicant should provide sufficient data to identify continatio menanc the essential variables related to powder quality and demonstrate that controlling an inert s eironment these variables within identified ranges will ensure reliable and adequate importa fts iein component properties and performance.

powder quality reducin

• At a minimum, the process qualification should consider the following essential Powder powder variality. variables for powder quality:

Feedstock

• Powder contamination is a critical o chemical composition, including trace elements Quality issue that may adversely affect o powder size and morphology distribution material properties and process by o powder flowability introducing oxides and changing o acceptance criteria or limits for powder reuse chemical composition.

• The applicant should identify additional specific essential variables and their ranges

• Thorough cleanliness activities, as appropriate.

dedication of LP-DED machines to Production Process Control and Verification specific alloys, and periodic

• During production, the applicant should demonstrate that process control and replacement of feedstock verification will maintain the production process within the qualified essential conveying tubes and components variable ranges.

Difference Key Technical Information Technical Review Guidelines can be conducted to address

• e ica can usa variety of wd ity apprcs tmonstr powder contamination. pr ess contr vificion, ilun but not limited to the fling, :

• LP-DED can achieve high powder o testing final components on a sampling basis utilization exceeding 90% in some o characterizing essential variables by routine powder sampling before initial use cases, which makes powder reuse and reuse less essential than in LPBF. o implementing procedures to minimize powder contamination during production

• Powder reuse can provide substantial cost benefits but can introduce significant variability in powder composition. Powder characterization and associated acceptance criteria may be warranted to reuse powder, especially for safety significant components.

• Wng wirftock is almt Process Qualification ways ed f LW -DED

• Through process qualification, the applicant should provide sufficient data to identify icis that is certified the the essential variables related to wire feedstock quality and demonstrate that mact tconfm to AWS controlling these variables within identified ranges will ensure reliable and adequate ISO strds f the scific l component properties and performance.

wirprt iquestio

• At a minimum, the process qualification should consider the following essential

• There is a long-established history variables for wire feedstock quality:

of ensuring welding consumables o chemical composition Wire conform to applicable standards for o material homogeneity Feedstock industrial welding applications. o surface condition, e.g., roughness Quality

• Wire chemistry and processing-o size path must be tightly controlled.

• The applicant should identify additional specific essential variables and their ranges

• Contamination concerns are well as appropriate.

understood and are less of a Production Process Control and Verification concern as compared to powder

• During production, the applicant should demonstrate that process control and feedstock. verification will maintain the production process within the qualified essential variable ranges.

• The applicant can use a variety of wire feedstock quality approaches to demonstrate process control and verification, including, but not limited to testing final components on a sampling basis.

Difference Key Technical Information Technical Review Guidelines

• Bud irtions (anne Process Qualification a) can vvy

• The applicant should identify the essential variables related to L-DED build process significant impact on quality the management and control and demonstrate that controlling these variables will cpone shoulb ensure reliable, adequate, and repeatable component properties and performance.

• In situ monitoring without feedback

• At a minimum, the process qualification should consider defining essential variables control can be used to identify with demonstration for the following:

issues in the build process in real o build interruption (e.g., duration, frequency, component location, and geometry) time and may be used in o loss of environmental control (e.g., event time, degree of air ingress).

conjunction with other approaches

• The ica siify ti specific sei viables apprrie.

to demonstrate process control. Production Process Control and Verification

• In situ monitoring with feedback

• The applicant should demonstrate that process control and verification will maintain L-DED Build control is still a developing area of the production process within the qualified essential variable ranges.

Process research and should be carefully

• The applicant can use a variety of approaches to demonstrate process control and Management managed and strongly verification, including, but not limited to, the following:

and Control demonstrated if proposed for use o monitoring build issues (e.g., incomplete spreading, delamination, or other during production. events that may result in component rejection)

• Management, storage, retrieval, o confirming build parameters, such as chemical composition and contamination and analysis of the data generated (e.g., oxides) during the L-DED process is critical o for location-specific measurements, measuring of materials properties for accelerating process (e.g., strength, hardness), appropriately demonstrating how they are optimization, although proper representative of geometry, size, location, and spatial orientation identification, handling, and o confirming of expected material microstructure and characteristics (e.g., residual evaluation of this information is still stress, porosity, surface finish) under development. o scrapping any builds that deviate from the qualified essential variable ranges.

• Due to the lack of maturity of the approach, in situ monitoring with feedback control should be adequately supported with a strong basis on the effectiveness of the approach.

• The most gy reentivtt Process Qualification scime arobtfrom end-

• The applicant should identify the component properties and characteristics for cpone ri. which witness testing will be used to demonstrate process qualification.

o Geometry impacts, particularly o Component properties and characteristics for which witness testing could be Witness thickness, on witness specimen used include various microstructure and material properties (e.g.,composition, Specimens microstructure and properties density, hardness, microstructure, tensile, fatigue, fracture toughness, corrosion should be considered and testing).

addressed.

• The applicant should demonstrate that witness specimens are representative of the

• Optimal witness specimen end-use component in terms of microstructure and material properties. At a parameters (geometry, size, minimum, the applicant should address the effects of differences between Difference Key Technical Information Technical Review Guidelines location, spatial orientation, and the witness specimens and the end-use component (e.g., geometry, size, frequency) depends highly on the location, and spatial orientation).

end-use component geometry and o One acceptable approach would be to benchmark witness specimen results to the goal of the witness testing end-use component results.

approach (e.g., monitoring build

• The applicant should discuss the witness testing methodology with regard issues as part of process control or to evaluation technique and frequency.

generating representative material properties data as part of process Production Process Control and Verification qualification).

• The applicant should discuss how witness testing will be used for process control

• When sectioning end-use and verification such that essential variables will be maintained within the qualified geometries is not feasible, ranges during the production process.

functional evaluations the

• The applicant can use a variety of witness specimen approaches to relationship between the demonstrate process control and verification, including, but not limited to, the acceptability of the end-use following:

geometries (e.g., burst tests, o monitoring build issues (e.g.,incomplete spreading, delamination, or other inspections) and the use of events that may result in component rejection) simplified witness specimen o confirming build parameters, such as chemical composition and contamination geometries would need to be (e.g.,oxides) demonstrated. o for location-specific measurements, measuring of materials properties (e.g.,strength, hardness), appropriately demonstrating how they are representative of geometry, size, location, and spatial orientation o confirming of expected material microstructure and characteristics (e.g.,residual stress, porosity, surface finish)

Difference Key Technical Information Technical Review Guidelines

• st -sing treatments Process Qualification wit hot istic pressing (HIP )

• For process qualification, the applicant should identify appropriate thermal post-rly designetide processing techniques for the fabricated component and demonstrate the intended twbenits: stress ri and/ effects of thermal post-processing on the final component.

ing, t liky v e little

• The applicant should provide sufficient data to identify the essential variables impact on pity or fls. related to thermal post-processing and demonstrate that controlling these variables o Stress relief heat treatments will within identified ranges will ensure reliable and adequate component properties and primarily reduce residual performance.

stresses from the as-built part

• At a minimum, the process qualification for thermal post-processing should consider without otherwise affecting the the following essential variables microstructure or properties. o for heat treatment: temperature profile over time, including heating rate, cooling o Annealing heat treatments rate, hold time at temperature, and environment during heat treatment should greatly reduce or o for HIP: temperature and pressure profile over time, including heating rate, eliminate residual stress as well cooling rate, hold time at temperature, and environment during heat treatment as coarsen the microstructure

• The applicant should identify additional specific essential variables as appropriate.

(to improve toughness) and reduce heterogeneity in Production Process Control and Verification microstructure and properties.

• During production, the applicant should demonstrate that process control and Thermal Post-

• HIP may be beneficial for reducing verification will maintain the production process within the qualified essential Processing residual stress, porosity, variable ranges for thermal post-processing.

heterogeneity, and internal cracks,

• The applicant can use a variety of approaches to demonstrate process control and while also coarsening the verification, including, but not limited to, the following:

microstructure (to improve o testing final components on a sampling basis toughness). o witness specimens

• For all thermal post-processing o validated monitoring of post-processing parameters during heat treatment or approaches, material-specific HIP process.

demonstration is important to identify adequate heat treatment or HIP parameters to achieve desired improvements in microstructure, properties, heterogeneity, porosity, and fabrication flaws.

• Thermal post-processing may significantly impact considerations related to the other L-DED-specific topics identified in lower rows (e.g.,

porosity, residual stress, initial fracture toughness).

Difference Key Technical Information Technical Review Guidelines

• The r ry on loc Process Qualification micrtrturoperti is

• Through process qualification, the applicant should provide sufficient data to the key ffces between demonstrate that local geometry impacts on material properties and microstructure L -DED oduced cpones will be addressed to ensure reliable and adequate component properties and cveily oced ones. performance.

• Local geometry significantly

• In the absence of demonstrated post-processing or build scan strategy to minimize impacts thermal profiles during or eliminate the local geometry impacts, the applicant needs to use an appropriate fabrication, which affects the local sampling methodology during process qualification to quantify the variability in microstructure and properties. materials properties and ensure adequate performance.

o For example, a thin section with

• The applicant should consider the following key factors affecting local geometry relatively rapid cooling rates will impacts by changing cooling rates and the resulting microstructure and properties:

likely have a much finer o local thickness variation microstructure than a thicker o local size or shape section with a slower cooling

• The ica siify ti specific faors as appropri rate due to more surrounding Supplemental Testing material being melted.

• The applicant should demonstrate that the local geometry impacts in an L-Local o As a result, local material DED-fabricated component will not unacceptably degrade material properties and Geometry properties such as strength, performance due to in-service aging.

Impacts on ductility and toughness will be o This demonstration should be performed on a sample that is representative of, Component affected by the variation in or bounds, the components qualified pre-service condition, including post-Properties microstructure as a function of processing.

and geometry.

Performance

• Post-processing and/or scan strategy refinement have the potential to minimize the local geometry impacts, however, the effects on properties and performance can vary significantly based on the geometry and materials used.

• If used, witness specimens representing the thinnest section are needed to bound material properties of component.

• The advantages of L-DED to fabricate components with as -built internal features can make inspection of the component features more difficult.

Difference Key Technical Information Technical Review Guidelines

• Hogeneity genly manifts Process Qualification witffent ties ithe buil

• Through process qualification, the applicant should provide sufficient data to rection rivtthe h tw demonstrate that heterogeneity and anisotropy in the L-DED build process will be rectis tthe nat the addressed to ensure reliable and adequate component properties and performance.

lay - -layer builocess. Ts

• In the absence of demonstrated thermal post-processing to minimize or eliminate impacts the micrtrtur the heterogeneity, the applicant needs to use an appropriate sampling methodology fabricion ft struct during process qualification to quantify the variability in materials properties and rly cre er properties ensure adequate performance.

Heterogeneity between buillers.

and

• Thermal post-processing with Anisotropy in appropriate parameters would be Supplemental Testing Properties expected to make material properties and performance more

• The applicant should demonstrate that the heterogeneity and anisotropy in an L-homogeneous and similar to DED-fabricated component will not unacceptably degrade material properties and conventional forged materials. performance through the service life of the component, including the effects of in-

• For example, in as-fabricated and service aging.

stress-relieved 316L, the variation o This demonstration should be performed on a sample that is representative of, in microstructure due to geometry or bounds, the components qualified pre-service condition, including thermal causes preferential crack growth post-processing.

directions for fatigue cracks.

• L-DED cponents tycly Process Qualification piesignifica -fabriced

• Through process qualification, the applicant should provide sufficient data to ri stress. demonstrate that residual stress will be addressed to ensure reliable and adequate

• High residual stress may result in component properties and performance and prevent unacceptable warping, warping, cracking, and cracking, and delamination.

delamination; however, these

• Post-processing through heat treatment, HIP, or both, would be expected to events typically can be visually address residual stress but should be demonstrated.

Residual detected.

Stress

• In addition, residual stress can Supplemental Testing make the component susceptible to

• The applicant should address, by testing if necessary, that the residual stresses in future degradation such as SCC or an L-DED-fabricated component will not significantly increase the susceptibility to fatigue from the presence of high in-service degradation mechanisms, such as SCC or fatigue.

tensile residual stress on the o This demonstration can be performed on a sample that is representative of, or surface. bounds, the components qualified pre-service condition, including post -

• Thermal post -processing with processing.

appropriate parameters would be expected to relieve residual stress.

Difference Key Technical Information Technical Review Guidelines

• rosity is kntversy Process Qualification ft filif SCC,

• Through process qualification, the applicant should provide sufficient data to irradiatn-ased resrroon demonstrate that porosity will be managed sufficiently to ensure reliable and cracking (IASCC ), tthe adequate component properties and performance.

ecisquaitivimct

• Post-processing through heat treatment, HIP, or both, may significantly reduce s on the mi and porosity; the applicant should demonstrate this.

porosity crtistics (p

• The applicant should consider the following key characteristics of porosity when fry, rsiz r assessing porosity:

mpholo, t v oid o pore density fraction). o pore distribution (e.g., location relative to the surface)

• Machine parameters and scan o pore size strategy refinement have the o pore morphology potential to address porosity o total void fraction Porosity concerns; however, they may vary

• The applicant should identify additional specific characteristics as appropriate.

significantly based on the geometry Supplemental Testing and materials used.

• The applicant should demonstrate that the porosity in an L-DED-fabricated

• Porosity is more prevalent in LP-component will not unacceptably degrade material properties and performance due DED than LW-DED due to the to in-service aging.

internal porosity and trapped gas in o This demonstration should be performed on a sample that is representative of, powder feedstock that does not or bounds, the components qualified pre-service condition, including post-exist in wire feedstock. processing.

• For post-processing, HIP with appropriate parameters has been demonstrated to reduce porosity and produce properties more similar to conventionally forged materials.

• Sf rghness is genly Process Qualification eater i -but L-DED pas

• Through process qualification, the applicant should provide sufficient data to Surface cped tsimilar fd demonstrate that surface roughness will be managed sufficiently to ensure reliable Finish mis. and adequate component properties and performance.

o The layer-by-layer nature of LP-

• Post-processing through precision machining, shot peening, or other surface DED combined with the treatment may be able to significantly reduce surface roughness but should be tendency to weld unmelted demonstrated.

Difference Key Technical Information Technical Review Guidelines powder particles to the Supplemental Testing component surfaces produces a

• The applicant should demonstrate that the surface finish in an L-DED-fabricated rough outer surface in LP-DED. component will not unacceptably degrade material properties and performance due o LW-DED typically has a bead-to in-service aging.

like surface due to the layer-by-o This demonstration should be performed on a sample that is representative of, layer deposition but does not or bounds, the components qualified pre-service condition, including post-have the added roughness of processing.

attached particles. Production Process Control and Verification

• Higher surface roughness can lead

• During production, the applicant should demonstrate that process control and to reduced fatigue life and reduced verification will maintain the production process within the qualified essential SCC and corrosion resistance. variable ranges for post-processing.

• Surface finish can be improved by

• The applicant can use a variety of approaches to demonstrate process control and post-processing such as verification, including, but not limited to, the following:

subtractive machining, or other o testing final components on a sampling basis surface treatments. o validated monitoring of post-processing parameters.

• For components with complicated geometries, hybrid manufacturing approaches (iterating between additive and subtractive steps) may be necessary to reach all surfaces for post-processing.

Table 2B. Technical Information and Review GuidelinesL -DED 316L Material-Specific Difference Key Technical Information Technical Review Guidelines

• High posity woulliky Process Qualification/Supplemental Testing tsilperformc

• For process qualification and supplemental testing, the applicant should provide an but woulveater analysis, supported by sufficient data in representative or bounding environments, to Tensile impact on h meri show adequate tensile properties for the design of the component.

Properties ties. o The corresponding analysis can demonstrate acceptable safety margins using approaches such as the following:

demonstrating equal or superior performance by comparison to tensile properties for conventionally manufactured materials analyzing design requirements to demonstrate sufficient tensile properties for the component

• Lited daton 316L -DED Process Qualification/Supplemental Testing mis vsw

• For process qualification and supplemental testing, the applicant should provide an significantly lower itial analysis, supported by sufficient data in representative or bounding environments, to frturtoughness show adequate fracture toughness for the intended function of the component.

nding on post - o The corresponding analysis can demonstrate acceptable safety margins using ocessing than similar approaches such as the following:

fmis. Ts m demonstrating equal or superior performance by comparison to fracture be trity or r toughness for conventionally manufactured materials defts that m be red analyzing design requirements to demonstrate sufficient fracture toughness for witoptimizeocessing design and flaw evaluation purposes params and therm Initial Fracture post-sing.

Toughness o However, 316L L-DED is still expected to have adequate initial toughness.

• Data in representative environments is important to demonstrate that fracture toughness will be adequate to meet component design assumptions.

• Thermal post-processing with appropriate parameters would be expected to improve fracture toughness.

Thermal Aging

• D ireesentiv Supplemental Testing/Performance Monitoring envirments is importa t Difference Key Technical Information Technical Review Guidelines demonstrate that fracture

• Tosent testi rformcmoti, the plicant sovide toughness does not degrade an ysis, srted by sficient datirresentiv bounng eirmts, to excessively due to thermal sw equatfrttoughns t therm agintoug the sviclife the aging and will be adequate to cpone.

meet component design o The corresponding analysis can demonstrate acceptable safety margins using assumptions. approaches such as the following:

• Thermal post-processing with demonstrating equal or superior performance by comparison to fracture appropriate parameters toughness after thermal aging for conventionally manufactured materials would be expected to make addressing uncertainties in the data on fracture toughness after thermal aging material properties and and the implications to in-service performance through conservative design performance more similar to assumptions, additional margins in analyses, surveillance programs, or additional conventional forged performance monitoring materials.

• D ireesentiv Supplemental Testing/Performance Monitoring envirments is importa t

• Through supplemental testing and performance monitoring, the applicant should provide demstrthat cnges i an analysis, supported by sufficient data in representative or bounding environments, to mi pformcdue t show adequate SCC and corrosion resistance for the intended function of the SCC wil n be degred t component.

eater gree iL -DED o The corresponding analysis can demonstrate acceptable safety margins by using mis tf approaches such as the following:

mis. demonstrating equal or superior performance by comparison to SCC and

• Post-processing with corrosion resistance performance for conventionally manufactured materials SCC and appropriate parameters addressing uncertainties in the data on SCC and corrosion resistance and the Corrosion would be expected to make implications to in-service performance through additional performance monitoring Resistance material properties and as appropriate performance more similar to conventional forged materials.

• In 316L, the silicon content in the powder can create oxides that have adverse effects on SCC growth rates.

Consideration should be given on oxide content in powder acceptance (virgin and recycled) criteria.

Fatigue

• Wit uatst - Supplemental Testing/Performance Monitoring ocessing, sf Difference Key Technical Information Technical Review Guidelines roughness is known to be a

• Tough sent testi rformcmoti, the plicant sovide greater issue with L-DED an ysis, srted by sficient datirresentiv bounng eirmts materials and can reduce lnctions, tsw adequ firfmatoug the svice life of fatigue life. the cpone.

• Fatigue properties are also o The applicant can use current fatigue management approaches supported by dependent on post-sufficient data for L-DED 316L to manage metal fatigue (e.g., cumulative usage processing heat treatment factors, cycle counting, EAF penalty factors).

and component porosity. o The corresponding analysis can demonstrate acceptable safety margins by using

• Limited data suggest high-approaches such as the following:

cycle fatigue life may be demonstrating equal or superior performance by comparison to fatigue testing for reduced compared to conventionally manufactured materials conventional 316L, while low-addressing uncertainties in the data on fatigue and the implications to in-service cycle fatigue life is performance through conservative design assumptions, additional margins in comparable to conventional analyses, surveillance programs, or additional performance monitoring 316L.

• Stress-relieved (without annealing heat treatment) L-DED 316L shows anisotropic fatigue strength and preferential crack growth directions due to the columnar microstructure.

• Data in representative environments is important to support fatigue calculations including environmentally-assisted fatigue (EAF) in L-DED materials.

• D ireesentiv Supplemental Testing/Performance Monitoring envirments is importa t

• Through supplemental testing and performance monitoring, the applicant should provide demstrthat irrai an analysis, supported by sufficient data in representative or bounding environments, to Irradiation effects will not be show adequate performance after irradiation (including irradiation-assisted SCC and loss Effects significantly greater iLDED - of toughness) for the intended function of the component throughout its service life.

mis tf o The corresponding analysis can demonstrate acceptable safety margins by using mis. approaches such as the following:

• Post-processing with demonstrating equal or superior performance by comparison to irradiation effects appropriate parameters for conventionally manufactured materials would be expected to make Difference Key Technical Information Technical Review Guidelines material properties and addrsinu erties it daton irraion fts and the ilications to performance more similar to in-ser rfmc tough cservivsigsio, ti conventional forged m ianys es, svllancoams, tional performamoting materials.

• Current studies point to reduced irradiation induced defects in L-DED components compared to conventional manufacturing.

However, the understanding is very limited, and research is ongoing. Additional research is likely needed to understand performance differences.

• r gtperur Supplemental Testing/Performance Monitoring ing vironments (

• Through supplemental testing and performance monitoring, the applicant should provide scussed iASME C an analysis, supported by sufficient data in representative or bounding environments, to Stion III, Division, dat show adequate performance after high temperature time-dependent aging effects irresentiv (including creep and creep-fatigue) for the intended function of the component throughout envirments imrtt its service life.

High tdemstrthat gh o The corresponding analysis can demonstrate acceptable safety margins by using Trur tpertime-depende approaches such as the following:

Time - aging fects iL-DED demonstrating equal or superior performance by comparison to high temperature Dendent mis will be ve t time-dependent aging effects for conventionally manufactured materials ing fects c eable w addressing uncertainties in the data on high temperature time-dependent aging

(, Creep cped tf effects and the implications to in-service performance through conservative Crp-mis. design assumptions, additional margins in analyses, surveillance programs, or Figue)

• Post-processing with additional performance monitoring appropriate parameters would be expected to make material properties and performance more similar to conventional forged materials.

Difference Key Technical Information Technical Review Guidelines

• D ireesentiv Supplemental Testing/Performance Monitoring envirments is importa t

• Through supplemental testing and performance monitoring, the applicant should provide demstrthat wds wit an analysis, supported by sufficient data in representative or bounding environments, to L -DED sm erials wi show adequate performance of the weld throughout the service life of the component.

perform similly tts o This analysis can be informed by relevant experience and knowledge of performance witcoentily of welds of conventional materials along with potential limited -scope testing on welds mact bas of L-DED materials.

Weld Integrity mis. o The corresponding analysis can demonstrate acceptable safety margins by using approaches such as the following:

demonstrating equal or superior performance by comparison to weld performance for conventionally manufactured materials addressing uncertainties in the data on weld performance and the implications to in-service performance through conservative design assumptions, additional margins in analyses, or additional performance monitoring

• Ther is very lited Process Qualification/Production Process Control and Verification isimioon the

• Through process qualification and production process control and verification, the rts triti jng applicant should provide sufficient data to demonstrate that weldability using traditional mhods beineon L-arc welding or other joining processes that may be required for component installation in DED cpents service can be performed consistently and reliably with sufficient quality to meet Code

• Higher oxygen content, acceptance criteria.

residual stress, and o This should include careful consideration of unique aspects of L-DED-fabricated Weldability / microstructural segregation materials compared to traditional manufacturing methods, including local geometry Joining may affect the optimal impacts on material properties (e.g., fracture toughness) and parameters for welding on L-heterogeneity/anisotropy, which are described in greater detail previously in this DED 316L compared to document.

conventional 316L.

• Weldability should be demonstrated for L-DED materials, but the existing welding standards and demonstration processes should be sufficient.