Stress values of compression, tension and torsion spring materials

Table 12-2-6 Stress values of compression, tension and torsion spring materials MPa

Wire Type			Oil Quenched-Tempered Spring Wire	Carbon Spring Wire Important Uses Carbon Spring Wire	Stainless steel wire for spring	Bronze wire Bronze plated wire (aged)	60Si2Mn,60Si2MnA 50CrA、55CrSiA 60CrMnA、60CrMnBA 60Si2Cra,60Si2Crva
Compression Spring	Test stress		0.550,	0.50	0.450,	0.40r,	710~890
	Static load allowable stress		0.500	0.450	0.400	0.36r,
	Dynamic load allowable shear stress	finite fatigue life	(.40-0.50	(0.38-0.45)0	70.34-0.40)0	70.33~0.36)0	568~712
		infinite fatigue life	70.35-0.40)0	70.33-0.38)0	0.30-0.36)0	70.30-0-33)0	426~534
Tension Spring	test shear stress		0.440、	0.40,	0.38r,	0.32o	475~596
	Static load allowable stress		0.40。	0.360	0.320,	0.300、
	Dynamic load allowable shear stress	finite fatigue life	70.32-0.40)0	(0.30-0.36)0	70.27-0.32)0	70.26~0.29)0,	405-507
		infinite fatigue life	(0.28-0.32)0	(0.27-030)☐	(0.24-0.30)0,	(0.24-0.28)0	356-447
Torsion Spring	Test bending stress		0.80,	0.78o	0.75o,	0.75o	994~1232
	Static load allowable bending stress		0.720,	0.70	0.680,	0.680,
	Dynamic load allowable bending stress	finite fatigue life	70.60-0.68)0	(0.58-0.66)0,	0.55-0.65)0,	70.55-0.65)0	795-986
		infinite fatigue life	(0.50-0.60)0	(0.49-0.58)0	70.45-0.55)0。	(0.45~0.55)0,	636-788

Note: 1 Take the intermediate value of tensile strength in table 12-2-3 and table 12-2-4 and the value in table 12-2-4 respectively.

2. For springs with material diameter d<1.0mm, the test shear stress is 90% of the value in the table

3. After the hot coil spring is formed, the hardness after heat treatment is 42~52hrc. When the hardness is the upper limit, the upper limit value in the table shall be taken.

The following points shall be paid attention to when selecting materials and determining allowable stress:

1. for important springs, if their damage has a significant impact on the whole machine, the allowable stress shall be appropriately reduced;

2. the spring treated by strong pressure can improve the fatigue limit, have obvious effect on improving the relaxation under load, and appropriately increase the allowable stress;

3. The shot peened spring can also improve the fatigue strength or fatigue life, and its allowable stress can be increased by 20%;

4. When the working temperature exceeds 60 ℃, the shear modulus G shall be corrected, and the correction formula is Gt =Kt G

Where G – shear modulus at normal temperature;
Gt- shear modulus at working temperature;
Kt- Temperature correction coefficient, its value is obtained from table 12-2-7.

Table 12-2-7 Temperature Correction Factor

Material	Operating temperature/℃				Material	Operating temperature℃
	≤60	150	200	250		≤60	150	200	250
	Kt
50CrVA 60Si2Mn 1Cr18Ni9Ti	1	0.96	0.95	0.94	1Cr17Ni7AL QBe2	1	0.95	0.94	0.92
	1	0.99	0.98	0.98		1	0.95	0.94	0.92
	1	0.98	0.94	0.9

Table 12-2-6 Stress values of compression, tension and torsion spring materials MPa

Table 12-2-7 Temperature Correction Factor

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