ASTM B795-20

Standard Test Method for Determining the Percentage of Alloyed or Unalloyed Iron Contamination Present in Powder Forged (PF) Steel Materials

SIGNIFICANCE AND USE
5.1 Cross-product contamination occurs whenever alloy steel powders are processed in the same equipment as iron powders.  
5.2 Unalloyed iron particles, because they may not harden upon heat treatment, are a potential source of soft spots in low-alloy steel parts.  
5.3 Alloyed iron particles, having higher hardenability than an iron or carbon steel matrix, are a potential source of hard spots.  
5.4 Hard or soft spots may cause problems in service or machining.  
5.5 The results of the tests may be used to qualify parts for shipment in accordance with guidelines agreed between purchaser and manufacturer or to check the suitability of mixes for use in powder forging.
SCOPE
1.1 This test method covers a metallographic procedure for determining the percentage of alloyed or unalloyed iron contamination present in powder forged low-alloy steel materials and the percentage of alloyed iron contamination in powder forged iron and carbon steel materials.  
1.2 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Mar-2020
• ICS: 77.160 - Powder metallurgy
• Technical Committee: B09 - Metal Powders and Metal Powder Products
• Drafting Committee: B09.11 - Near Full Density Powder Metallurgy Materials

Relations

• Refers: ASTM B243-18 - Standard Terminology of Powder Metallurgy
• Effective Date: 01-Oct-2018
• Refers: ASTM B243-16 - Standard Terminology of Powder Metallurgy
• Effective Date: 01-Jul-2016
• Refers: ASTM E177-14 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2014
• Refers: ASTM B243-13 - Standard Terminology of Powder Metallurgy
• Effective Date: 01-Nov-2013
• Refers: ASTM E177-13 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2013
• Refers: ASTM B243-12 - Standard Terminology of Powder Metallurgy
• Effective Date: 15-Jul-2012
• Refers: ASTM B243-11 - Standard Terminology of Powder Metallurgy
• Effective Date: 15-Nov-2011
• Refers: ASTM E177-10 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Oct-2010
• Refers: ASTM B243-10 - Standard Terminology of Powder Metallurgy
• Effective Date: 15-Jan-2010
• Refers: ASTM B243-09a - Standard Terminology of Powder Metallurgy
• Effective Date: 15-Dec-2009
• Refers: ASTM B243-09 - Standard Terminology of Powder Metallurgy
• Effective Date: 01-Jan-2009
• Refers: ASTM E177-08 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Oct-2008
• Refers: ASTM B243-08a - Standard Terminology of Powder Metallurgy
• Effective Date: 15-Mar-2008
• Refers: ASTM B243-08 - Standard Terminology of Powder Metallurgy
• Effective Date: 01-Feb-2008
• Refers: ASTM E3-01(2007) - Standard Guide for Preparation of Metallographic Specimens
• Effective Date: 01-Jul-2007

Overview

ASTM B795-20 is the international standard that defines a test method for determining the percentage of alloyed or unalloyed iron contamination in powder forged (PF) steel materials. Developed by ASTM International, this standard is critical in the context of powder metallurgy, where the cleanliness and composition of materials have a direct impact on quality and performance. The procedure outlined utilizes metallographic analysis to detect and quantify contamination levels, ensuring that powder forged parts meet the necessary criteria for operational integrity and reliability.

This test method is applicable to a range of powder forged materials, specifically addressing contamination in low-alloy steel, iron, and carbon steel products. By identifying cross-product contamination, manufacturers can avoid the presence of detrimental soft or hard spots in finished PF components, contributing to improved performance and consistency across industrial applications.

Key Topics

• Cross-Product Contamination: The unintentional mixing of alloyed and unalloyed iron powders during production can result in contamination of the final steel product. This contamination is often caused by processing different powders using the same equipment.
• Material Performance: Unalloyed iron contamination can lead to soft spots that may not respond to heat treatment, while alloyed iron particles can cause hard spots that affect machinability and durability. Both scenarios can lead to performance or service issues in the finished part.
• Metallographic Procedure: The standard prescribes a systematic method for sample preparation, including sectioning, polishing, etching, and microscopic examination at 100× magnification. Quantification is achieved through a point-count method, allowing precise determination of contaminant percentages.
• Quality Control: Test results are used to qualify powder forged parts for shipment and to validate powder blends prior to use, according to purchaser and manufacturer agreements.

Applications

The ASTM B795-20 standard is widely used in industries where powder metallurgy and powder forging are core processes, such as automotive, aerospace, and heavy machinery manufacturing. Key practical applications include:

• Supplier and Manufacturer Agreements: Ensuring shipped components meet contractual cleanliness and quality requirements.
• Product Development and Material Validation: Verifying the suitability and quality of powder mixes before large-scale production.
• Process Improvement: Identifying sources of contamination to refine manufacturing workflows and improve equipment cleaning protocols.
• Failure Analysis: Investigating the root cause of mechanical issues in PF parts, where contamination-induced hard or soft spots are suspected.

By implementing ASTM B795-20 testing, organizations enhance product reliability and reduce the likelihood of in-service failures due to inconsistent material properties.

Related Standards

ASTM B795-20 references and aligns with several other ASTM standards relevant to powder metallurgy and metallographic analysis, including:

• ASTM B243: Terminology of Powder Metallurgy, providing definitions and context for key terms.
• ASTM E3: Guide for Preparation of Metallographic Specimens, detailing sample preparation techniques to ensure accurate analysis.
• ASTM E177: Practice for Use of the Terms Precision and Bias in ASTM Test Methods, establishing the statistical foundation for measurement uncertainty and repeatability.
• ASTM E691: Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method.

These related standards offer guidance on terminology, sample preparation, and statistical methods, ensuring that contamination testing for powder forged steel materials is consistent, accurate, and internationally recognized.

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Keywords: ASTM B795-20, iron contamination, powder forged (PF) steel, powder metallurgy, metallographic analysis, alloyed iron, unalloyed iron, cross-product contamination, quality control, material qualification, standard test method.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: B795 − 20
Standard Test Method for
Determining the Percentage of Alloyed or Unalloyed Iron
Contamination Present in Powder Forged (PF) Steel
Materials
This standard is issued under the fixed designation B795; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* information is available in the Related Material Section of Vol
02.05 of the Annual Book of ASTM Standards.
1.1 This test method covers a metallographic procedure for
determining the percentage of alloyed or unalloyed iron 3.2 Definitions of Terms Specific to This Standard:
contamination present in powder forged low-alloy steel mate- 3.2.1 cross-product contamination, n—the unintentional
rials and the percentage of alloyed iron contamination in mixing of powders with distinct differences in chemical
powder forged iron and carbon steel materials. composition.
1.2 Units—The values stated in SI units are to be regarded
4. Summary of Test Method
asstandard.Nootherunitsofmeasurementareincludedinthis
standard. 4.1 Asection representing the core region is taken from the
powder forged material and prepared for metallographic ex-
1.3 This standard does not purport to address all of the
amination.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4.2 The polished and etched sample is examined micro-
priate safety, health, and environmental practices and deter-
scopically at a magnification of 100× and a systematic point
mine the applicability of regulatory limitations prior to use.
count made of features with etching characteristics different
1.4 This international standard was developed in accor-
from that of the matrix.
dance with internationally recognized principles on standard-
4.3 The amount of contaminant is reported as a percentage
ization established in the Decision on Principles for the
to the nearest 0.1%.
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
5. Significance and Use
Barriers to Trade (TBT) Committee.
5.1 Cross-product contamination occurs whenever alloy
2. Referenced Documents
steel powders are processed in the same equipment as iron
powders.
2.1 ASTM Standards:
B243Terminology of Powder Metallurgy
5.2 Unalloyed iron particles, because they may not harden
E3Guide for Preparation of Metallographic Specimens
upon heat treatment, are a potential source of soft spots in
E177Practice for Use of the Terms Precision and Bias in
low-alloy steel parts.
ASTM Test Methods
5.3 Alloyed iron particles, having higher hardenability than
an iron or carbon steel matrix, are a potential source of hard
3. Terminology
spots.
3.1 Definitions—Definitions of powder metallurgy terms
5.4 Hard or soft spots may cause problems in service or
can be found in Terminology B243. Additional descriptive
machining.
5.5 The results of the tests may be used to qualify parts for
This test method is under the jurisdiction of ASTM Committee B09 on Metal
shipment in accordance with guidelines agreed between pur-
Powders and Metal Powder Products and is the direct responsibility of Subcom-
mittee B09.11 on Near Full Density Powder Metallurgy Materials.
chaserandmanufacturerortocheckthesuitabilityofmixesfor
Current edition approved April 1, 2020. Published June 2020. Originally
use in powder forging.
approved in 1988. Last previous edition approved in 2013 as B795–13. DOI:
10.1520/B0795-20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 6. Apparatus
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
6.1 Equipment for the metallographic preparation of test
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. specimens.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B795 − 20
6.2 A metallographic microscope permitting observation 8.1.2.2 Agoodcontrastisdevelopedbetweenthematrixand
and measurement at a magnification of 100×. the contaminant because of a combination of etching and
staining.The areas containing the highest alloy content are the
7. Sampling
least affected. Unalloyed iron will become darkened in a
low-alloy matrix, and low-alloy particles will remain light in
7.1 Takeametallographicspecimenfromthepowderforged
material. The polished surface of the specimen should be not an iron or carbon steel matrix. In a low-alloy matrix, contami-
nantparticlesofanotherlow-alloypowdercanbedistinguished
less than that required to superimpose 2500 grid points at a
magnificationof100×.Multiplesectionsarepermittedinorder from unalloyed iron contamination because the particles etch
differently (see Fig. 1 and Fig. 2).
to obtain the necessary area for measurement on small parts or
test pieces.
8.2 Examination—Superimpose a grid of between 100 and
250systematicallyplacedpointsupona100×magnifiedimage
7.2 The polished surface shall be parallel to the direction of
forging, that is, parallel to the direction of travel of the forging (that is, a field of view) of the polished and etched specimen.
Count and record the number of grid points falling upon
punch, or as specified in the contract or purchase order, and
shall represent an area away from the surface of the material. contaminant particles; if necessary, a separate count may be
kept to distinguish between alloy contamination and unalloyed
8. Procedure
iron contamination in low-alloy steel materials, or, types of
alloy contaminant in iron or carbon steel materials. (See Note
8.1 Preparation of Specimens:
1.) Counting of randomly selected discrete fields should be
8.1.1 Polishing—In polishing the specimens, it is highly
continued until at least 2500 grid points have been superim-
important that the polished surface be free from artifacts and
posed on the specimen. The total number of points falling on
debris. It is recommended that the procedures described in
contaminant particles f
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: B795 − 13 B795 − 20
Standard Test Method for
Determining the Percentage of Alloyed or Unalloyed Iron
Contamination Present in Powder Forged (PF) Steel
Materials
This standard is issued under the fixed designation B795; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This test method covers a metallographic procedure for determining the percentage of alloyed or unalloyed iron
contamination present in powder forged low-alloy steel materials and the percentage of alloyed iron contamination in powder
forged iron and carbon steel materials.
1.2 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this
standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
B243 Terminology of Powder Metallurgy
E3 Guide for Preparation of Metallographic Specimens
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3. Terminology
3.1 Definitions—Definitions of powder metallurgy terms can be found in Terminology B243. Additional descriptive information
is available in the Related Material Section of Vol 02.05 of the Annual Book of ASTM Standards.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 cross-product contamination—contamination, n—the unintentional mixing of powders with distinct differences in
chemical composition.
4. Summary of Test Method
4.1 A section representing the core region is taken from the powder forged material and prepared for metallographic
examination.
4.2 The polished and etched sample is examined microscopically at a magnification of 100× and a systematic point count made
of features with etching characteristics different from that of the matrix.
4.3 The amount of contaminant is reported as a percentage to the nearest 0.1 %.
This test method is under the jurisdiction of ASTM Committee B09 on Metal Powders and Metal Powder Products and is the direct responsibility of Subcommittee B09.11
on Near Full Density Powder Metallurgy Materials.
Current edition approved Oct. 1, 2013April 1, 2020. Published November 2013June 2020. Originally approved in 1988. Last previous edition approved in 20072013 as
B795 – 07.B795 – 13. DOI: 10.1520/B0795-13.10.1520/B0795-20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B795 − 20
5. Significance and Use
5.1 Cross-product contamination occurs whenever alloy steel powders are processed in the same equipment as iron powders.
5.2 Unalloyed iron particles, because they may not harden upon heat treatment, are a potential source of soft spots in low-alloy
steel parts.
5.3 Alloyed iron particles, having higher hardenability than an iron or carbon steel matrix, are a potential source of hard spots.
5.4 Hard or soft spots may cause problems in service or machining.
5.5 The results of the tests may be used to qualify parts for shipment in accordance with guidelines agreed between purchaser
and manufacturer or to check the suitability of mixes for use in powder forging.
6. Apparatus
6.1 Equipment for the metallographic preparation of test specimens.
6.2 A metallographic microscope permitting observation and measurement at a magnification of 100×.
7. Sampling
7.1 Take a metallographic specimen from the powder forged material. The polished surface of the specimen should be not less
than that required to superimpose 2500 grid points at a magnification of 100×. Multiple sections are permitted in order to obtain
the necessary area for measurement on small parts or test pieces.
7.2 The polished surface shall be parallel to the direction of forging, that is, parallel to the direction of travel of the forging
punch, or as specified in the contract or purchase order, and shall represent an area away from the surface of the material.
8. Procedure
8.1 Preparation of Specimens:
8.1.1 Polishing—In polishing the specimens, it is highly important that the polished surface be free from artifacts and debris.
It is recommended that the procedures described in PracticeGuide E3 be followed. Automated grinding and polishing procedures
are recommended.
8.1.2 Etching—Lightly etch the freshly polished specimen with 2 % nital (2 mL nitric acid, 98 mL ethyl alcohol). Next, etch
the polished and lightly etched specimen by immersion in a freshly prepared aqueous solution containing 3 g potassium
metabisulfite and 10 g sodium thiosulfate per 100 mL. Rinse the specimen in running water, then rinse with low residue alcohol
and dry with a blast of dry air.
8.1.2.1 The etching time will depend on alloy type, carbon content, and microstructure. The greater the alloy content, the slower
the etching rate; the greater the carbon content, the faster the etching rate.
8.1.2.2 A good contrast is developed between the matrix and the contaminant because of a combination of etching and staining.
The areas containing the highest alloy content are the least affected. Unalloyed iron will become darkened in a low-alloy matrix,
and low-alloy particles will remain light in an iron or carbon steel matrix. In a low-alloy matrix, contaminant particles of another
low-alloy powder can be distinguished from unalloyed iron contamination because the particles etch differently (see Fig. 1 and Fig.
FIG. 1 Illustration of Iron and Low-Alloy Contaminants in PF-4650
B795 − 20
2).
8.2 Examination—Superimpose a grid of between 100 and 250 systematically placed points upon a 100× magnified image (that
is, a field of view) of the polished and etched specimen. Count and record the number of grid points falling upon contaminant
particles; if necessary, a separate count may be kept to distinguish between alloy contamination and unalloyed iron contamination
in low-alloy steel materials, or, types of alloy contaminant in iron or carbon steel materials. (See Note 1.) Counting of randomly
selected discrete fields should be continued until at least 2500 grid points have been superimposed on the specimen. The total
number of points falling on contaminant particles for all fields counted shall b
...