Heat treatment of austenitic stainless spring steel
(1)Solution treatment
Specification for solid solution treatment of austenitic stainless spring steel
Material grade processing temperature ℃ cooling method equipment
1Cr18Ni9 bars: 1100～1150 water cooling 1. High temperature salt furnace is suitable for bars and thick plates
2. Vacuum oil quenching furnace or vacuum air quenching furnace is suitable for thin plates, strips, pipes and small precision elastic components
Plate: 1080～1130 water or oil cooling
Strip material: 1020～1070 water cooling, oil cooling or air cooling
1Cr18Ni9Ti bar: 1060～1140 water cooling
Plate: 1050～1130 water or oil
Strip material: 1020～1070 water cooling, oil cooling or air cooling
0Cr17Ni14Mo21020～1120 water cooling, oil cooling or air cooling
0Cr18Ni12Mo2Ti1020～1100 water cooling, oil cooling or air cooling
1Cr18Ni12Mo2Ti1020～1100 water cooling, oil cooling or air cooling
(2) Stable tempering treatment
Specification for stable tempering treatment of austenitic stainless spring steel
Material grade processing temperature ℃ Holding time (h) equipment
1Cr18Ni9430～4802h vacuum furnace
or
Aging furnace
1Cr18Ni9Ti
0Cr17Ni14Mo2380～4802n
0Cr18Ni12Mo2Ti
1Cr18Ni12Mo2Ti
Remarks: The steel wire strengthened by cold drawing and the cold forming spring is used for stress relief and tempering specification. See Table 2
2. Heat treatment of martensitic stainless spring steel
(1) Preliminary heat treatment of martensitic stainless spring steel. Martensitic stainless spring steel belongs to martensite transformation strengthened steel.
Preliminary heat treatment process of martensitic stainless spring steel
Material grade incomplete annealing Low temperature annealing
Heating temperature °C cooling medium Brinell hardness indentation mm Heating temperature °C cooling medium Brinell hardness indentation mm
2Cr13870-900 is cooled to 600℃ with the furnace, and then out of the furnace. Air cooling ≥4.4730～780 Air ≥4.0
3Cr13≥4.2730～780≥4.0
4Cr13≥4.0730～780≥4.0
1Cr17Ni2670～690≥3.5
(2) Quenching and tempering treatment of martensitic stainless spring steel
The final heat treatment after martensitic stainless spring steel is made into a spring is quenching and tempering.
The final heat treatment process of commonly used martensitic stainless spring steel
Material designation Quenching Tempering hardness (HRC)
Heating temperature ℃ Cooling medium Heating temperature ℃ Cooling medium
2Cr131000～1040 oil 300～480 air
3Cr131000～1040 Oil 300～480 Air 40～46
3Cr13Mo1020～1060 oil 220～300 air 46～50
4cr131000～1050 oil 320～450 air 45～52
1cr17Ni21000～1020 oil 340～360 air
3. Heat treatment of precipitation hardening stainless spring steel
Precipitation hardening stainless spring steel is strengthened by both martensite transformation strengthening and precipitation precipitation strengthening, so the basic heat treatment process is solution treatment and aging treatment.
For semi-austenitic sports steel, unstable austenite is obtained at room temperature after solution treatment, martensite transformation is not completed, and insufficient strengthening. Therefore, between solution treatment and aging treatment, an adjustment treatment is added to make the The stable austenite is transformed into martensite. Commonly used adjustment treatments include adjustment treatment (T treatment), cold treatment (R treatment), and plastic treatment (C treatment).
Common precipitation hardening stainless spring steel heat treatment process
Category Material grade Solution treatment Adjustment treatment Aging treatment
Heating temperature ℃ Cooling medium Heating temperature ℃ Cooling medium
Semi-austenite precipitation strengthening type 0Cr17Ni7AI1040～1060 Water or air 750～770℃ Air cooling 520～550 air
940～960℃ air cooling -78℃ cold treatment 500～520
Cold deformation 470～490
0Cr15Ni7Mo2AI1050～1080 air or water 750～770℃ air cooling 520～550 air
940～960℃ air cooling -78℃ cold treatment 500～520
Cold deformation 470～490
0Cr12Mn5Ni4Mo3AI1040～1060 air 750～770℃ air cooling 450～490 air
-78℃ cold treatment 510～530
550～570
Cold deformation 340～360
510～570
550～570
Martensite precipitation strengthening type 0Cr17Ni4Cu4Nb 1020～1060 air 450～550 air
Supplement: 1.1.1-②The influence of stress relief tempering temperature on spring mechanical properties
The effect of stress relief tempering temperature on the mechanical properties of springs of various materials is objective. The effect of different tempering temperatures on the mechanical properties of carbon spring steel wires, oil-quenched and tempered steel wires and 1Cr18Ni9 spring materials can be explained. See Tables 3, 4. and 5 (the previous article listed Table 5 as Table 3), and the corresponding tempering temperature can also be determined according to the special performance requirements of the spring.
The effect of tempering temperature on the mechanical properties of carbon spring steel wire material spring
Steel wire diameter mm Material supply status σb, σs, after 30 minutes of various tempering temperature treatments
(Mpa)100℃200℃260℃300℃400℃
2 Cold drawn strengthening σb 17601850185017501625
σs13501500160013801300
Effect of Tempering Temperature on Mechanical Properties of Oil Quenched and Tempered Steel Wire Spring
Σb and σs after 30 minutes of various tempering temperature treatments for steel wire diameter mm
(Mpa)100℃200℃300℃400℃500℃
2 Cold drawn strengthening σb 15201550160016001350
σs14001400140013801200
The effect of tempering temperature on the mechanical properties of 1Cr18Ni9 spring
Steel wire diameter mm Material supply status Hardness (HRC) after 1 hour at various tempering temperatures
300℃350℃400℃450℃500℃
4 Cold drawn strengthening 46.648.248.248.547.6
644.045.545.145.344.9