Technical guide · 2026-08-03
Spring & Heat-Resistant Steel
Spring steels are designed for elastic energy, fatigue and set resistance, while heat-resistant engineering steels retain strength or oxidation resistance during elevated-temperature exposure. This navigation group presents both branches but does not imply that one grade can satisfy both duties.
01
Definition and boundary
Room-temperature spring fatigue and long-term creep/oxidation are different design problems with different tests, standards and processing controls.
Reference information only: final acceptance is controlled by the ordered product specification, condition, dimensions and certified test results.
02
How the material system works
Alloy chemistry changes hardenability, tempering response, toughness or elevated-temperature stability.
Heat treatment develops the usable microstructure and must be tied to section size.
Cleanliness, segregation and surface condition influence fatigue and reliability.
03
Representative grades and systems
| Grade or system | Selection focus | Qualification |
|---|---|---|
| 5160/6150/51CrV4 | Cr or Cr-V spring steels selected by section, fatigue and heat treatment. | Verify the ordered product specification, condition and dimensions before substitution. |
| 13CrMo4-5 / T/P11 | Established Cr-Mo elevated-temperature systems under pressure standards. | Verify the ordered product specification, condition and dimensions before substitution. |
| 11CrMo9-10 / T/P22 | Higher Cr-Mo pressure/creep system requiring dedicated code control. | Verify the ordered product specification, condition and dimensions before substitution. |
04
Properties and trade-offs
Properties are condition- and section-specific rather than chemistry-only.
Higher hardenability or strength can reduce welding and machining margin.
Fatigue performance requires cleanliness and surface-integrity control.
05
Product forms and supply conditions
06
Applications and selection
Applications and selection
- Coil and leaf springs, torsion bars
- Boiler, refinery and power piping
- High-temperature fasteners and pressure components
Properties and trade-offs
- Define final component loads, life, temperature and failure mode.
- Select grade and hardenability for section and heat-treatment capability.
- Set inspection and process controls around the critical property.
07
Fabrication, durability and inspection
Match austenitizing, quench and temper or case-hardening procedure to section size and required microstructure.
Control decarburization, grain size, residual stress, straightness and distortion through the full route.
Qualify welding and repair separately; preheat, consumables and post-weld treatment depend on grade and restraint.
08
Procurement checklist
- Specify exact designation, product standard, melt practice, size and supply/heat-treatment condition.
- Define hardenability, cleanliness, grain size, decarburization, UT, hardness and mechanical tests as applicable.
- State machining allowance, surface class, straightness, traceability and final component heat treatment.
09
Standards, sources and review
Standards and designation context
- SAE designation/composition standards for SAE grades
- ASTM A29/A322 for applicable bar products
- EN/ISO/AMS or component standards for alternate systems and final acceptance