Search common steel grades or applications to find indicative tempering temperature ranges, typical working temperatures and practical heat-treatment references.
Tempering temperature is selected after hardening and quenching to obtain a suitable balance between hardness, strength, toughness and dimensional stability. The appropriate temperature depends on the steel grade and the required service properties.
| Steel | Equivalent / Standard | Category | Indicative Tempering Range | Typical Application |
|---|---|---|---|---|
| AISI 1045 | C45 / EN8 | Carbon Steel | 200–650 °C | General machine components |
| AISI 4140 | 42CrMo4 / EN19 | Alloy Steel | 200–650 °C | Shafts, bolts, gears |
| AISI 4340 | 34CrNiMo6 / EN24 | Alloy Steel | 200–650 °C | High-strength components |
| AISI 5160 | 50CrV4 | Spring Steel | 300–550 °C | Springs and resilient components |
| AISI 52100 | 100Cr6 / EN31 | Bearing Steel | 150–250 °C | Bearing components |
| AISI O1 | 1.2510 | Tool Steel | 150–250 °C | Cold-work tooling |
| AISI A2 | 1.2363 | Tool Steel | 150–550 °C | Dies and cutting tools |
| AISI D2 | 1.2379 / SKD11 | Tool Steel | 150–550 °C | Wear-resistant dies and tooling |
| AISI H13 | 1.2344 / SKD61 | Tool Steel | 500–650 °C | Hot-work tooling |
| AISI M2 | 1.3343 / SKH51 | Tool Steel | 500–600 °C | High-speed cutting tools |
Tempering is a controlled heat-treatment stage normally performed after steel has been hardened and quenched. The hardened steel is reheated to a selected temperature, held for an appropriate time and then cooled.
The main purpose is to reduce excessive brittleness while retaining an appropriate level of hardness and strength. Tempering also helps relieve stresses introduced during hardening.
For many hardened carbon and alloy steels, increasing the tempering temperature generally decreases hardness and increases toughness and ductility. The exact relationship is strongly dependent on steel chemistry and the preceding hardening treatment.
A low tempering temperature may be selected where high hardness and wear resistance are important. Higher tempering temperatures are commonly used when toughness and dimensional stability are more important.
Medium-alloy steels such as 4140 and 4340 are frequently quenched and tempered for shafts, gears, fasteners and other loaded components. Tempering is selected according to the required mechanical properties rather than simply choosing the highest possible hardness.
For these steels, a broad tempering range may be available, but the final temperature should be selected using the required hardness or mechanical-property target and the applicable material specification.
Spring steels require a combination of strength, hardness and resilience. Grades such as 5160 and 6150 are commonly tempered at temperatures higher than those used for very low-temperature wear-focused treatments.
The final temperature depends on the required spring properties, section size and exact steel specification.
Bearing steels such as 52100 are normally treated to achieve high hardness and wear resistance. Their tempering temperatures are generally much lower than those commonly used for tough quenched-and-tempered structural alloy steels.
Bearing components require particularly controlled heat treatment because dimensional stability, retained austenite and hardness can strongly affect service performance.
Tool steels require grade-specific tempering schedules. Some cold-work tool steels are tempered at relatively low temperatures, while hot-work and high-speed steels generally require substantially higher tempering temperatures.
Multiple tempering cycles may also be specified for certain tool steels. Manufacturer heat-treatment instructions should therefore take priority over generic reference ranges.
Some highly alloyed tool steels exhibit secondary hardening during tempering. Alloy carbides can precipitate during higher-temperature tempering, producing a hardness response that differs from ordinary low-alloy steels.
This is particularly important for high-speed steels and some hot-work and high-alloy tool steels. Their tempering schedules should not be inferred from carbon-steel behavior.
The values provided by this tool are indicative engineering reference ranges. A tempering temperature should not be selected from this tool alone for a critical production component.
What temperature is 4140 tempered at?
4140 can be tempered across a broad range, commonly from roughly 200°C to 650°C depending on the required hardness and mechanical properties.
What temperature is 1045 tempered at?
1045 can be tempered across a broad range depending on the desired hardness, strength and toughness. Approximately 200–650°C covers many practical reference conditions.
Does higher tempering temperature mean softer steel?
For many carbon and low-alloy steels, increasing tempering temperature generally reduces hardness and increases toughness, although the exact response is grade-specific.
Can hardened steel be used without tempering?
Freshly hardened steel can contain high residual stresses and excessive brittleness. Tempering is normally performed promptly after hardening when the grade and process call for it.
Is tempering temperature the same for all applications?
No. The desired balance of hardness, strength, toughness and wear resistance changes with the application.
Can this lookup replace a manufacturer's heat-treatment specification?
No. It is a preliminary reference tool. The applicable material specification and supplier heat-treatment data should control production processing.