ISO 4491-2:2023 PDF

Metallic powders — Determination of oxygen content by reduction methods — Part 2: Loss of mass on hydrogen reduction (hydrogen loss)

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Title (English):

ISO 4491-2:2023

Metallic powders — Determination of oxygen content by reduction methods — Part 2: Loss of mass on hydrogen reduction (hydrogen loss)

Document status:: Active
Format:: Electronic (PDF)
Number of pages:: 8
Publication date:: April 19, 2023
Edition:: ISO IS 4491 edition 3 version 1
ICS:: 77.160

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Description (English):

This document specifies a method for the determination of the relative loss of mass which a metallic powder undergoes when heated in a stream of pure dry hydrogen under specified conditions. The purpose of this test is to evaluate a chemical powder characteristic which is of importance to the powder metallurgical industry. The test is not intended as a means for the determination of the content of specific elements (see Annex A and ISO 4491-1). The test method is applicable to unalloyed, partially alloyed and completely alloyed powders of the metals listed in Table 1 (see 7.2.1). It is not applicable to lubricated powders or to mixtures of metal powders.

Technical details

Technical committee: ISO/TC 119/SC 2 - Sampling and testing methods for powders (including powders for hardmetals)
SKU: ISO 4491-2:2023

Abstract

Overview

ISO 4491-2:2023 - Metallic powders - Determination of oxygen content by reduction methods - Part 2: Loss of mass on hydrogen reduction (hydrogen loss) defines a standardized laboratory test to evaluate the relative loss of mass a metallic powder exhibits when heated in a stream of pure, dry hydrogen. The method is intended as a chemical characteristic important to the powder metallurgy industry and complements other oxygen-determination methods (see ISO 4491-1 and Annex A). It is not a direct measure of specific elemental contents and is not applicable to lubricated powders or mixtures of metal powders.

Key topics and technical requirements

Scope and applicability: Applies to unalloyed, partially alloyed and fully alloyed metal powders listed in Table 1 (examples include tin, tin bronze, silver, copper, iron/steel, cobalt, nickel, tungsten, molybdenum, rhenium).
Gas quality: Hydrogen and purge gases (nitrogen or argon) must have maximum oxygen 0.005% mass fraction and dew point ≤ −45 °C.
Apparatus: Electrically heated tubular furnace with controlled temperature zone, gas-tight quartz or refractory tube (25–40 mm ID), enclosed thermocouple (±5 °C), laboratory balance (±0.1 mg), ceramic boat (powder depth ≤ 3 mm) and gas supply with flow meters.
Sampling and sample size: Test as-received powder; two determinations per sample; typical test portion ≈ 5 g (smaller for low apparent density powders).
Test procedure: Purge with N2/Ar, replace with H2 at specified flow (≥ 25 mm/s gas speed), maintain prescribed reduction temperature and time from Table 1, re-purge and cool under inert gas, weigh before and after.
Result calculation: Hydrogen loss = (mass loss ÷ initial powder mass) × 100 (%). Report mean of two determinations with specified expression and permitted differences.
Precision statement: Includes inter-laboratory repeatability and reproducibility data for representative powders (e.g., iron, copper, tungsten).

Applications and users

Quality control laboratories in metal powder production and powder metallurgy
Materials characterization for sintering, pressing and consolidation processes
R&D groups assessing powder chemical state and oxygen-related behavior
Suppliers verifying batch-to-batch consistency of alloy powders

This standard helps ensure comparable, reproducible hydrogen loss testing across labs, supporting product specifications, process control, and material selection.

Related standards

ISO 4491-1 (related reduction methods and interpretation; consult for element-specific determinations)
Other ISO/CEN powder metallurgy testing standards (see ISO catalogue)

Keywords: ISO 4491-2:2023, metallic powders, hydrogen loss, oxygen content determination, powder metallurgy, reduction methods, loss of mass on hydrogen reduction, test method, precision.

Related standards

Mentioned in the description and other ISO standards

Abstract

Overview

Key topics and technical requirements

Scope and applicability: Applies to unalloyed, partially alloyed and fully alloyed metal powders listed in Table 1 (examples include tin, tin bronze, silver, copper, iron/steel, cobalt, nickel, tungsten, molybdenum, rhenium).
Gas quality: Hydrogen and purge gases (nitrogen or argon) must have maximum oxygen 0.005% mass fraction and dew point ≤ −45 °C.
Apparatus: Electrically heated tubular furnace with controlled temperature zone, gas-tight quartz or refractory tube (25–40 mm ID), enclosed thermocouple (±5 °C), laboratory balance (±0.1 mg), ceramic boat (powder depth ≤ 3 mm) and gas supply with flow meters.
Sampling and sample size: Test as-received powder; two determinations per sample; typical test portion ≈ 5 g (smaller for low apparent density powders).
Test procedure: Purge with N2/Ar, replace with H2 at specified flow (≥ 25 mm/s gas speed), maintain prescribed reduction temperature and time from Table 1, re-purge and cool under inert gas, weigh before and after.
Result calculation: Hydrogen loss = (mass loss ÷ initial powder mass) × 100 (%). Report mean of two determinations with specified expression and permitted differences.
Precision statement: Includes inter-laboratory repeatability and reproducibility data for representative powders (e.g., iron, copper, tungsten).

Applications and users

Quality control laboratories in metal powder production and powder metallurgy
Materials characterization for sintering, pressing and consolidation processes
R&D groups assessing powder chemical state and oxygen-related behavior
Suppliers verifying batch-to-batch consistency of alloy powders

This standard helps ensure comparable, reproducible hydrogen loss testing across labs, supporting product specifications, process control, and material selection.

Related standards

ISO 4491-1 (related reduction methods and interpretation; consult for element-specific determinations)
Other ISO/CEN powder metallurgy testing standards (see ISO catalogue)

Keywords: ISO 4491-2:2023, metallic powders, hydrogen loss, oxygen content determination, powder metallurgy, reduction methods, loss of mass on hydrogen reduction, test method, precision.

ISO 4491-2:2023 PDF

Technical details

Abstract

Overview

Key topics and technical requirements

Applications and users

Related standards

Related standards

Abstract

Overview

Key topics and technical requirements

Applications and users

Related standards

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