ISO 4955:2016

Overview

ISO 4955:2016 - Heat-resistant steels defines requirements for steels and two related alloys intended for service at temperatures typically above 550 °C, where resistance to hot gases, combustion products and/or long-term mechanical stress (creep) is critical. The standard applies to a range of product forms including flat products, bars, sections, rods, semi‑finished products and forgings, and sets out designation, chemical composition, mechanical properties, surface quality, inspection and testing requirements.

Key topics and technical requirements

• Scope and classification
  • Covers heat‑resistant and creep‑resistant grades classified by microstructure: austenitic, ferritic, martensitic, and precipitation‑hardening.
• Chemical composition
  • Cast analysis limits are specified (product analysis permitted deviations are listed in the standard).
• Mechanical properties
  • Requirements for room‑temperature and elevated‑temperature tensile properties, plus creep behaviour (creep strength to 1% strain and creep rupture strength).
  • Annexes include technical creep data to support design and selection.
• Delivery condition and process routes
  • Specifies agreed heat treatments, surface finishes and process routes (tables provide treatment and finish options).
• Surface quality and tolerances
  • Defines acceptable surface conditions, maximum discontinuity depths for bars/rods/sections and dimensional tolerances.
• Inspection, testing and documentation
  • Specifies inspection procedures, types of inspection documents (per ISO 10474), sample selection, test methods and retest rules.
• Marking and purchaser information
  • Lists information purchasers must supply (grade, product form, dimensions, treatment condition, inspection certificate type, etc.).

Practical applications

ISO 4955:2016 is used to specify materials for components exposed to high temperatures and long‑term loading, such as:

• industrial furnaces and combustion systems
• power‑generation boilers and heat exchangers
• petrochemical and process equipment with high‑temperature streams It helps ensure material selection, supply quality and traceability for components where heat resistance, creep resistance and high‑temperature mechanical performance are primary requirements.

Who uses this standard

• Material engineers and metallurgists selecting high‑temperature steels
• Procurement specialists specifying supplier requirements
• Manufacturers and steel producers for production and quality control
• QA inspectors and testing laboratories performing conformity checks
• Designers requiring creep and elevated‑temperature property data

Related standards

• ISO 404 - General technical delivery requirements (applicable)
• ISO 10474 - Inspection documents
• ISO 16143‑1/2/3 - Stainless and heat‑resistant wire (related product coverage)
• ISO 683‑15 - Heat‑resistant steels for valves
• ISO 377, ISO 9443, ISO 20723 - Sampling, surface and dimensional references

ISO 4955:2016 provides a practical framework for specifying, producing and verifying heat‑resistant steels, streamlining material selection for high‑temperature industrial applications.