ML21074A040

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AMT Subtask 1A - Draft Guidelines Document for Additive Manufacturing - Laser Powder Bed Fusion
ML21074A040
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Issue date: 07/07/2021
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THE NRC STAFF HAS PREPARED THIS DRAFT DOCUMENT AND IS RELEASING IT TO SUPPORT THE SEPTEMBER 8, 2021, PUBLIC WEBINAR ON DRAFT GUIDELINES FOR 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 Powder Bed Fusion

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 powder bed fusion (LPBF).

These guidelines are based on the NRC assessment of the safety significance of the identified differences between LPBF and traditional manufacturing methods as documented in NRC Technical Assessment of Additive ManufacturingLaser Powder Bed Fusion, (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20351A204)

(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 ReactorsLaser Powder Bed Fusion Additive Manufacturing, (ADAMS Accession No. ML20351A217). This document provides LPBF-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 guidelines document, Draft AMT Review Guidelines (ADAMS Accession No. ML21074A037) (hereafter, 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 LPBF-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 Powder Bed Fusion The purpose of this section is to describe the NRC technical assessment of LPBF, which provides the technical basis for the technical review guidelines described in this DGD. The primary objective of the NRC technical assessment is to describe the differences between an LPBF-fabricated component and a traditionally manufactured component, assess the safety significance of the identified differences, and identify relevant technical information pertaining to these differences for LPBF-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 LPBF.

An important note should be made with regard to discussions of safety significance in both the NRC technical assessment and this LPBF DGD. The safety significance of each identified

difference in the context of these documents refers to the impact on component performance.

The overall impact to plant safety 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 staff identified the 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 Powder Bed Fusion-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): process 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 production and utilization 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 LPBF 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 generic 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

not 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 requirements (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 LPBF processes identified in the table and achieved through successful performance of the other four Appendix A items: process qualification, supplemental testing, production process control and verification, and performance monitoring.

Tables 2A and 2B provide the technical review guidelines. Table 2A lists the generic differences between traditional manufacturing and LPBF. Table 2B lists the material-specific differences between traditional manufacturing and LPBF 316L stainless steel. 316L is the alloy relevant to LPBF-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 likely need to be considered for any newly fabricated material using LPBF. In general, material-specific data for the proposed processing and post-processing parameters are important for any nuclear LPBF-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)).

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

  • Difference: identifies the differences between LPBF 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 LPBF and traditional manufacturing that the staff should consider when evaluating how a licensees or applicants submittal addresses the differences between LPBF and traditional manufacturing

Table 1. Relevant Elements from Appendix A to the Generic Guidelines Production Process Performance Difference Process Qualification Supplemental Testing Control and Verification Monitoring LPBF machine process X X control Powder quality X X LPBF build process X X management and control Witness specimens X X Post-processing X X Local geometry impacts on component properties and X X performance Heterogeneity and X X anisotropy in properties Residual stress X X Porosity X X Surface finish X X Tensile properties X X Initial fracture toughness X X X

Thermal aging X X

SCC X X

Fatigue X X

Irradiation effects X High Temperature Time-Dependent Aging Effects X X

(e.g., Creep and Creep-Fatigue)

X Weld integrity X Weldability/joining X X Table 2A. Technical Information and Review GuidelinesLPBF Generic Difference Key Technical Information Technical Review Guidelines

  • Careful control of LPBF file preparation Process Qualification is needed to ensure process control.
  • The applicant should identify the essential variables related to LPBF machine Improper file control can significantly process control and demonstrate that controlling these variables within impact final component properties and identified ranges will ensure reliable, adequate, and repeatable component performance and affect fabrication properties and performance.

replication.

  • At a minimum, the process qualification should consider the following essential
  • Machine calibration is vital for variables:

fabrication replication, particularly o software file preparation (e.g., LPBF software version, and LPBF software LPBF contamination minimization when settings) machine recycling powder, ensuring correct laser o calibration of LPBF machine and subsystems (e.g., build stage, powder process power and beam shape, and ensuring hopper, laser optics, atmosphere control) control atmospheric quality control in addition to

  • The applicant should identify additional specific essential variables and their geometric tolerances. ranges as appropriate.

Production Process Control and Verification

  • During production, the applicant should demonstrate that process control and verification will maintain the production process within the qualified essential variable ranges.
  • One possible approach for machine process control that the applicant can use to demonstrate process control and verification is periodic machine calibration verification.
  • Powder contamination is a critical issue Process Qualification that may adversely affect material
  • Through process qualification, the applicant should provide sufficient data to properties and process by introducing identify the essential variables related to powder quality and demonstrate that oxides and changing chemical controlling these variables within identified ranges will ensure reliable and Powder composition. adequate component properties and performance.

quality

  • Powder should always be sieved before
  • At a minimum, the process qualification should consider the following essential using because unsieved powder may variables for powder quality:

not be representative of composition, as o chemical composition, including trace elements elemental composition and phases may o powder size and morphology distribution o powder flowability

Difference Key Technical Information Technical Review Guidelines not be uniformly distributed across the o acceptance criteria or limits for powder reuse powder size range.

  • The applicant should identify additional specific essential variables and their
  • Powder reuse acceptance/rejection ranges as appropriate.

depends on routinely sampling and Production Process Control and Verification characterizing powder after sieving.

  • During production, the applicant should demonstrate that process control and The LPBF system, sieving system, and verification will maintain the production process within the qualified essential maintenance of inert environment are all variable ranges.

important factors that influence the

  • The applicant can use a variety of powder quality approaches to demonstrate amount of powder reuse that can be process control and verification, including, but not limited to, the following:

done without affecting component o testing final components on a sampling basis (e.g., witness specimens with performance. demonstration of applicability)

  • For example, in 316L, silicon and o characterizing essential variables by routine sampling after sieving powders manganese content in the powder can before initial use and reuse create oxides that have adverse effects o implementing procedures to minimize powder contamination during on SCC growth rates. Consideration production should be given to oxide content in powder acceptance (virgin and recycled) criteria.
  • Build interruptions (planned and Process Qualification unplanned) can have a very significant
  • The applicant should identify the essential variables related to LPBF build impact on the quality of the component process management and control and demonstrate that controlling these and should be avoided. variables will ensure reliable, adequate, and repeatable component properties
  • In situ monitoring without feedback and performance.

control can be used to identify issues in

  • At a minimum, the process qualification should consider defining essential the build process in real time and may variables with demonstration for the following:

be used alone or in conjunction with o build interruption (e.g., duration, frequency, component location, and LPBF build other approaches to demonstrate geometry) process process control. o loss of environmental control (e.g., event time, degree of air ingress).

management

  • In situ monitoring with feedback control
  • The applicant should identify additional specific essential variables as and control (e.g., reapplying a powder layer, appropriate.

adjusting laser/environmental Production Process Control and Verification parameters) is still a developing area of

  • The applicant should identify the process control and verification approaches research and should be carefully (e.g., in situ monitoring, AI) used during the build process and demonstrate managed. during process qualification how these approaches will ensure that a quality
  • While artificial intelligence (AI) is component will be produced.

commonly used to flag defects for o Due to the lack of maturity of the approach, in situ monitoring with feedback human review, lack of AI-flagged control should be adequately supported with a strong basis on the effectiveness of the approach.

Difference Key Technical Information Technical Review Guidelines defects should not be interpreted as no

  • One possible approach the applicant can use to demonstrate build process existing defects. management and control is to scrap any builds that deviate from the qualified
  • One limitation of all build chamber essential variable ranges.

surface monitoring methods is that only the top surface is observed.

  • The most highly representative test Process Qualification specimens are obtained from end-use
  • The applicant should identify the component properties and characteristics for component geometries. which witness testing will be used to demonstrate process qualification.

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

  • Optimal witness specimen parameters
  • The applicant should demonstrate that witness specimens are representative of (geometry, size, location, spatial the end-use component in terms of microstructure and material properties. At orientation, and frequency) depend a minimum, the applicant should address how the witness specimens consider highly on the end-use component geometry, size, location, and spatial orientation.

geometry and the goal of the witness o One acceptable approach would be to benchmark witness specimen results testing approach (e.g., monitoring build to end-use component results.

issues as part of process control or

  • The applicant should discuss the witness testing methodology with regard to Witness generating representative material evaluation technique and frequency.

specimens properties data as part of process Production Process Control and Verification qualification).

  • The applicant should discuss how witness testing will be used for process
  • When sectioning end-use geometries is control and verification such that essential variables will be maintained within not feasible, functional evaluations of the qualified ranges during the production process.

end-use geometries such as burst tests

  • The applicant can use a variety of witness specimen approaches to are recommended in conjunction with demonstrate process control and verification, including, but not limited to, the simplified witness specimen geometries.

following:

o monitoring build issues (e.g., incomplete spreading, delamination, or other events that may result in component rejection) o confirming build parameters, such as chemical composition and contamination (e.g., oxides) 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

  • Post-processing heat treatments without Process Qualification HIP generally are designed to provide
  • For process qualification, the applicant should identify appropriate post-two benefitsstress relief and processing techniques for the fabricated component and demonstrate the annealingbut likely have little impact intended effects of post-processing on the final component.

on porosity or flaws.

  • The applicant should provide sufficient data to identify the essential variables o Stress-relief heat treatments will related to post-processing and demonstrate that controlling these variables primarily reduce residual stresses within identified ranges will ensure reliable and adequate component properties from the as-built part without and performance.

otherwise affecting the

  • At a minimum, the process qualification for post-processing heat treatments microstructure or properties. should consider the following essential variables for post-processing:

o Annealing heat treatments should o for heat treatment: temperature profile over time, including heating rate, greatly reduce or eliminate residual cooling rate, hold time at temperature, and environment during heat stress as well as coarsen the treatment microstructure (to improve o for HIP: temperature and pressure profile over time, including heating rate, toughness) and reduce cooling rate, hold time at temperature, and environment during heat heterogeneity in microstructure and treatment properties.

  • The applicant should identify additional specific essential variables as
  • HIP may be beneficial for reducing appropriate.

Post- residual stress, porosity, heterogeneity, processing and internal cracks, while also Production Process Control and Verification coarsening the microstructure (to

  • During production, the applicant should demonstrate that process control and improve toughness). verification will maintain the production process within the qualified essential
  • For all post-processing approaches, variable ranges for post-processing.

material-specific demonstration is

  • The applicant can use a variety of approaches to demonstrate process control important to identify adequate heat and verification, including, but not limited to, the following:

treatment or HIP parameters to achieve o testing final components on a sampling basis (e.g., witness specimens with desired improvements in microstructure, demonstration of applicability) properties, heterogeneity, porosity, and o validated monitoring of post-processing parameters during heat treatment fabrication flaws. or HIP process.

  • Other types of post-processing techniques (e.g., machining, shot peening, chemical treatments) can be used to address or improve component performance.
  • Post-processing may significantly impact considerations related to the other LPBF-specific topics identified in lower rows in the table.

Difference Key Technical Information Technical Review Guidelines

  • The role of geometry on local Process Qualification microstructure and properties is one of
  • Through process qualification, the applicant should provide sufficient data to the key differences between demonstrate that local geometry impacts on material properties and LPBF-produced components and microstructure will be addressed to ensure reliable and adequate component conventionally produced components. properties and performance.
  • Local geometry significantly impacts
  • In the absence of demonstrated post-processing or build scan strategy to thermal profiles during fabrication, which minimize or eliminate the local geometry impacts, the applicant needs to use affects the local microstructure and an appropriate sampling methodology during process qualification to quantify properties. the variability in 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 likely have a much finer properties:

microstructure than a thicker section o local thickness variation with a slower cooling rate due to o local size or shape Local more surrounding material being

  • The applicant should identify additional specific key factors as appropriate.

geometry melted. Supplemental Testing impacts on o As a result, local material properties

  • The applicant should demonstrate that the local geometry impacts in an component such as strength, ductility, and LPBF-fabricated component will not unacceptably degrade material properties properties toughness will be affected by the and performance due to in-service aging.

and variation in microstructure as a o This demonstration should be performed on a sample that is representative performance function of geometry. of, or bounds, the components qualified pre-service condition, including

  • Witness specimens can be used to post-processing.

assess local geometry impacts but should be carefully demonstrated to be applicable to the end-use geometry.

  • Post-processing and scan strategy refinement can potentially minimize the local geometry impacts; however, they can vary significantly based on the geometry and materials used.
  • Varying processing parameters is potentially another method to compensate for the effect of geometry and minimize local geometry impacts.

This is a less mature approach.

Difference Key Technical Information Technical Review Guidelines

  • Heterogeneity generally manifests with Process Qualification different properties in the build direction
  • Through process qualification, the applicant should provide sufficient data to relative to the other two directions due demonstrate that heterogeneity and anisotropy in the LPBF build process will to the nature of the layer-by-layer build be addressed to ensure reliable and adequate component properties and process. This impacts the performance.

microstructure and fabrication defect

  • In the absence of demonstrated post-processing to minimize or eliminate the structure and generally creates poorer heterogeneity, the applicant needs to use an appropriate sampling Heterogeneity properties between build layers. methodology during process qualification to quantify the variability in materials and
  • Post-processing with appropriate properties and ensure adequate performance.

anisotropy in parameters would be expected to make properties material properties and performance more homogeneous and similar to Supplemental Testing conventional forged materials.

  • The applicant should demonstrate that the heterogeneity and anisotropy in an
  • For example, in as-fabricated and LPBF-fabricated component will not unacceptably degrade material properties stress-relieved 316L, the variation in and performance due to in-service aging.

microstructure due to geometry also o This demonstration should be performed on a sample that is representative causes fatigue and SCC cracks to of, or bounds, the components qualified pre-service condition, including preferentially travel in the build direction post-processing.

should they initiate.

  • High residual stress may result in Process Qualification warping, cracking, and delamination;
  • Through process qualification, the applicant should provide sufficient data to however, these events typically can be demonstrate that residual stress will be addressed to ensure reliable and detected visually. adequate component properties and performance and prevent unacceptable
  • In addition, residual stress can make the warping, cracking, and delamination.

component susceptible to future

  • Post-processing through heat treatment, HIP, or both, would be expected to degradation such as SCC or fatigue address residual stress but should be demonstrated.

Residual from the presence of high tensile stress residual stress on the surface. Supplemental Testing

  • Post-processing with appropriate
  • The applicant should address, by testing if necessary, that the residual parameters would be expected to stresses in an LPBF-fabricated component will not significantly increase the relieve residual stress. susceptibility to in-service degradation mechanisms, such as SCC or fatigue.

o This demonstration should be performed on a sample that is representative of, or bounds, the components qualified pre-service condition, including post-processing.

  • Porosity is known to adversely affect Process Qualification fatigue life, SCC, and
  • Through process qualification, the applicant should provide sufficient data to Porosity irradiation-assisted SCC, though the demonstrate that porosity will be managed sufficiently to ensure reliable and precise quantitative impact depends on adequate component properties and performance.

Difference Key Technical Information Technical Review Guidelines the material and porosity characteristics

  • Post-processing through heat treatment, HIP, or both, may significantly reduce (e.g., pore density/distribution, pore porosity; the applicant should demonstrate this.

size, pore morphology, and total void

  • The applicant should consider the following key characteristics of porosity fraction). when assessing porosity:
  • Machine parameters and scan strategy o pore density refinement have the potential to address o pore distribution (e.g., location relative to the surface) porosity concerns; however, they may o pore size vary significantly based on the geometry o pore morphology and materials used. o total void fraction
  • For post-processing, HIP (with
  • The applicant should identify additional specific characteristics as appropriate.

appropriate parameters) has been Supplemental Testing demonstrated to reduce porosity and

  • The applicant should demonstrate that the porosity in an LPBF-fabricated produce properties more similar to component will not unacceptably degrade material properties and performance conventionally forged materials. due to in-service aging.

o This demonstration should be performed on a sample that is representative of, or bounds, the components qualified pre-service condition, including post-processing.

  • Surface roughness is generally greater Process Qualification in as-built LPBF parts compared to
  • Through process qualification, the applicant should provide sufficient data to similar forged materials. demonstrate that surface roughness will be managed sufficiently to ensure
  • Higher surface roughness can lead to reliable and adequate component properties and performance.

reduced fatigue life and reduced

  • Post-processing through precision machining, shot peening, or other surface corrosion resistance. treatment may be able to significantly reduce surface roughness but should be
  • Surface finish can be improved by post- demonstrated.

Surface finish processing such as precision Supplemental Testing machining, or other surface treatment.

  • The applicant should demonstrate that the surface finish in an LPBF-fabricated component will not unacceptably degrade material properties and performance due to in-service aging.

o This demonstration should be performed on a sample that is representative of, or bounds, the components qualified pre-service condition, including post-processing.

Table 2B. Technical Information and Review GuidelinesLPBF 316L Material Specific Difference Key Technical Information Technical Review Guidelines

  • Tensile properties for LPBF Process Qualification/Supplemental Testing 316L are generally equal or
  • For process qualification and supplemental testing, the applicant should provide an superior to those of analysis, supported by sufficient data in representative or bounding environments, to conventional 316L, even in the show adequate tensile properties for the design of the component.

Tensile weaker direction in the as-built o The corresponding analysis can demonstrate acceptable safety margins using properties condition. approaches such as the following:

  • High porosity could degrade demonstrating equal or superior performance by comparison to tensile properties tensile performance but would for conventionally manufactured materials likely have a greater impact on analyzing design requirements to demonstrate sufficient tensile properties for the other material properties. component
  • Data in representative Process Qualification/Supplemental Testing environments are important to
  • For process qualification and supplemental testing, the applicant should provide an demonstrate that fracture analysis, supported by sufficient data in representative or bounding environments, to Initial toughness will be adequate to show adequate fracture toughness for the intended function of the component.

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

  • Post-processing with demonstrating equal or superior performance by comparison to fracture appropriate parameters would toughness for conventionally manufactured materials be expected to improve analyzing design requirements to demonstrate sufficient fracture toughness for fracture toughness. design and flaw evaluation purposes
  • Data in representative Supplemental Testing/Performance Monitoring environments are important to
  • Through supplemental testing and performance monitoring, the applicant should provide demonstrate that fracture an analysis, supported by sufficient data in representative or bounding environments, to toughness does not degrade show adequate fracture toughness after thermal aging throughout the service life of the excessively from thermal aging component.

Thermal and will be adequate to meet o The corresponding analysis can demonstrate acceptable safety margins using aging component design approaches such as the following:

assumptions. demonstrating equal or superior performance by comparison to fracture

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

Difference Key Technical Information Technical Review Guidelines

  • Data in representative Supplemental Testing/Performance Monitoring environments are important to
  • Through supplemental testing and performance monitoring, the applicant should provide demonstrate that changes in an analysis, supported by sufficient data in representative or bounding environments, to material performance due to show adequate SCC resistance for the intended function of the component.

SCC will not be degraded to a o The corresponding analysis can demonstrate acceptable safety margins by using greater degree in LPBF approaches such as the following:

SCC materials than forged demonstrating equal or superior performance by comparison to SCC performance materials. for conventionally manufactured materials

  • Post-processing with addressing uncertainties in the data on SCC and the implications to in-service appropriate parameters would performance through additional performance monitoring as appropriate be expected to make material properties and performance more similar to conventional, forged materials.
  • Surface roughness is known to Supplemental Testing/Performance Monitoring be a greater issue with LPBF
  • Through supplemental testing and performance monitoring, the applicant should provide materials, which can reduce an analysis, supported by sufficient data in representative or bounding environments and fatigue life. loading conditions, to show adequate fatigue performance throughout the service life of
  • Fatigue properties are strongly the component.

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

  • Data in representative o The corresponding analysis can demonstrate acceptable safety margins by using environments are important to approaches such as the following:

support fatigue calculations, demonstrating equal or superior performance by comparison to fatigue testing for including environmentally conventionally manufactured materials assisted fatigue (EAF), in LPBF addressing uncertainties in the data on fatigue and the implications to in-service materials. performance through conservative design assumptions, additional margins in analyses, surveillance programs, or additional performance monitoring

Difference Key Technical Information Technical Review Guidelines

  • Data in representative Supplemental Testing/Performance Monitoring environments are important to
  • Through supplemental testing and performance monitoring, the applicant should provide demonstrate that irradiation an analysis, supported by sufficient data in representative or bounding environments, to effects in LPBF materials will show adequate performance after irradiation (including irradiation-assisted SCC and loss be equivalent to or acceptable of toughness) for the intended function of the component throughout its service life.

Irradiation when compared to forged o The corresponding analysis can demonstrate acceptable safety margins by using effects materials. approaches such as the following:

  • Post-processing with demonstrating equal or superior performance by comparison to irradiation effects appropriate parameters would for conventionally manufactured materials be expected to make material addressing uncertainties in the data on irradiation effects and the implications to properties and performance in-service performance through conservative design assumptions, additional more similar to conventional margins in analyses, surveillance programs, or additional performance monitoring forged materials.
  • For high temperature operating Supplemental Testing/Performance Monitoring environments (as discussed in
  • Through supplemental testing and performance monitoring, the applicant should provide ASME Code Section III), data an analysis, supported by sufficient data in representative or bounding environments, to in representative environments show adequate performance after high temperature time-dependent aging effects High are important to demonstrate (including creep and creep-fatigue) for the intended function of the component throughout Temperature that high temperature time- its service life.

Time- dependent aging effects in o The corresponding analysis can demonstrate acceptable safety margins by using Dependent LPBF materials will be approaches such as the following:

Aging equivalent to or acceptable demonstrating equal or superior performance by comparison to high temperature Effects (e.g., when compared to forged time-dependent aging effects for conventionally manufactured materials Creep and materials. addressing uncertainties in the data on high temperature time-dependent aging Creep-

  • Post-processing with effects and the implications to in-service performance through conservative Fatigue) appropriate parameters would design assumptions, additional margins in analyses, surveillance programs, or be expected to make material additional performance monitoring properties and performance more similar to conventional forged materials.

Difference Key Technical Information Technical Review Guidelines

  • Data in representative Supplemental Testing/Performance Monitoring environments are important to
  • Through supplemental testing and performance monitoring, the applicant should provide demonstrate that welds with an analysis, supported by sufficient data in representative or bounding environments, to LPBF base materials will show adequate performance of the weld throughout the service life of the component.

perform similarly to those with o This analysis can be informed by relevant experience and knowledge of performance conventionally manufactured of welds of conventional materials along with potential limited-scope testing on welds base materials. of LPBF materials.

Weld o The corresponding analysis can demonstrate acceptable safety margins by using integrity 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

  • Limited data show a narrower Process Qualification/Production Process Control and Verification weld parameter range may be
  • Through process qualification and production process control and verification, the appropriate for LPBF 316L. applicant should provide sufficient data to demonstrate that weldability using traditional arc welding or other joining processes that may be required for component installation in Weldability/

service can be performed consistently and reliably with sufficient quality to meet Code joining acceptance criteria.

o This should include careful consideration of unique aspects of LPBF-fabricated materials compared to traditional manufacturing methods, including local geometry impacts on material properties (e.g. fracture toughness) and heterogeneity/anisotropy, which are described in greater detail previously in this document.

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