Technical guide · 2026-08-21
Spring & Heat-Resistant Steel
This navigation page contains two deliberately separate branches: spring steels selected for cyclic elastic duty and relaxation resistance, and heat-resistant engineering steels selected for creep, oxidation and pressure-code service. They share heat-treatment concepts, not one performance claim.
01
Definition and boundary
Do not use a room-temperature spring fatigue argument to select creep-resistant pressure material, or a T/P pressure grade as a generic spring steel.
Reference information only: final acceptance is controlled by the ordered product specification, condition, dimensions and certified test results.
02
How the material system works
Spring duty stores elastic energy and is controlled by cyclic stress, surface integrity, set and relaxation.
Spring-bar hardenability must develop the required tempered structure through the active section.
Heat-resistant pressure duty is controlled by time-dependent creep, oxidation and microstructural stability.
Welding and post-weld heat treatment can dominate high-temperature joint life.
03
Representative grades and systems
| Grade or system | Selection focus | Qualification |
|---|---|---|
| 5160/6150/51CrV4 | Spring-steel choices selected by active section, fatigue duty, surface condition and heat treatment. | Identify spring or high-temperature branch first, then apply its own product standard, life model, tests and process qualification. |
| 13CrMo4-5 / T/P11 | Cr-Mo elevated-temperature pressure systems under dedicated product and construction rules. | Identify spring or high-temperature branch first, then apply its own product standard, life model, tests and process qualification. |
| 11CrMo9-10 / T/P22 | Higher-alloy pressure/creep branch whose weld and PWHT controls are not spring practice. | Identify spring or high-temperature branch first, then apply its own product standard, life model, tests and process qualification. |
04
Properties and trade-offs
Spring fatigue and sag resistance depend on surface, residual stress and tempered structure.
Spring hardenability must match wire/bar size and quench route.
Creep strength is time-, temperature-, product- and condition-specific.
Oxidation and weld-zone stability can control heat-resistant service.
05
Product forms and supply conditions
06
Applications and selection
Applications and selection
- Coil and leaf springs, torsion bars and stabilizers
- Valve springs and fatigue-critical elastic components
- Boiler, refinery and power piping
- High-temperature pressure components and fasteners
Properties and trade-offs
- Choose the spring branch for cyclic elastic duty; choose the heat-resistant branch for time-at-temperature duty.
- For springs, define stress range, active section, surface state and shot-peening strategy.
- For heat-resistant service, define design temperature, life, code, pressure boundary and weld condition.
- Use separate acceptance documents and never infer one branch from the other's grade list.
07
Fabrication, durability and inspection
Control spring decarburization, quench response, tempering and surface finishing before fatigue enhancement.
Validate shot peening and presetting against the finished spring geometry.
Qualify high-temperature welding, consumables, preheat and PWHT to the construction code.
Maintain temperature-cycle and repair records for creep-sensitive pressure components.
08
Procurement checklist
- For springs, state ASTM A689-25 or the applicable wire/flat standard, grade, section and condition.
- Add hardenability, decarburization, surface class, fatigue validation and shot-peening requirements as needed.
- For heat-resistant products, state exact T/P or other grade, product standard, code edition and design temperature.
- Define weld/PWHT, creep-property documentation, NDT and traceability separately for the pressure branch.
09
Standards, sources and review
Standards and designation context
- ASTM A689-25 for applicable hot-wrought general-purpose spring bars
- SAE J404 and applicable hardenability standards for SAE alloy spring chemistries
- Dedicated ASTM/ASME/EN product specifications and construction codes for heat-resistant pressure grades
- Component fatigue or creep design documents control finished service acceptance