Spring Steel Grade And Chemical Composition

Release Time: 2025-04-28

Spring Steel | ASTM A 568

Steel Designation No.	Chemical Composition Limits, Percent
Steel Designation No.	C	Mn	P max	S max
1040	0.36-0.44	0.60-0.90	0.030	0.035
1042	0.39-0.47	0.60-0.90	0.030	0.035
1043	0.39-0.47	0.70-1.00	0.030	0.035
1045	0.42-0.50	0.60-0.90	0.030	0.035
1046	0.42-0.50	0.70-1.00	0.030	0.035
1049	0.45-0.53	0.60-0.90	0.030	0.035
1050	0.47-0.55	0.60-0.90	0.030	0.035
1055	0.52-0.60	0.60-0.90	0.030	0.035
1060	0.55-0.60	0.60-0.90	0.030	0.035
1064	0.59-0.70	0.50-0.80	0.030	0.035
1065	0.59-0.70	0.60-0.90	0.030	0.035
1070	0.65-0.76	0.60-0.90	0.030	0.035
1074	0.69-0.80	0.50-0.80	0.030	0.035
…	…	…	…	…

Spring Steel | G.4802 (1983)

Grade	C %	Si %	Mn %	Cr %	Ni %	P ≤%	S ≤%
S 50C	0.47-0.53	0.15-0.35	0.60-0.90	≤0.20	≤0.20	0.030	0.035
S 55C	0.52-0.58	0.15-0.35	0.60-0.90	≤0.20	≤0.20	0.030	0.035
S 60C	0.55-0.65	0.15-0.30	0.60-0.90	≤0.20	≤0.20	0.030	0.035
S 65C	0.60-0.70	0.15-0.30	0.60-0.90	≤0.20	≤0.20	0.030	0.035
S 70C	0.65-0.75	0.15-0.30	0.60-0.90	≤0.20	≤0.20	0.030	0.035
S K4	0.90-1.10	≤0.35	≤0.50	≤0.20	≤0.25	0.030	0.030
S K5	0.80-0.90	≤0.35	≤0.50	≤0.20	≤0.25	0.030	0.030

Classification of Spring Steel

1. Carbon spring steel:

Carbon spring steel is the most fundamental type of spring steel, mainly composed of iron and carbon. Spring steel can be classified into low-carbon, medium-carbon and high-carbon types based on the difference in carbon content. Low-carbon spring steel is mainly used for manufacturing springs that require high toughness, such as automotive suspension springs. Medium carbon and high carbon spring steels are used to manufacture springs that require higher strength and hardness, such as engine valve springs.

2. Alloy spring steel:

Alloy spring steel is based on carbon spring steel and adds alloying elements (such as silicon, manganese, chromium, vanadium, etc.) to improve its mechanical properties and heat treatment performance. Alloy spring steel features higher strength, hardness and fatigue resistance, making it suitable for manufacturing springs that bear greater loads and complex stresses.

spring steel figure

3. Stainless steel spring steel:

Stainless steel spring steel has excellent corrosion resistance and is mainly used to manufacture springs that need to work in corrosive environments. This type of spring steel usually contains a relatively high amount of chromium and nickel elements to enhance its corrosion resistance.

4. Heat-resistant spring steel:

Heat-resistant spring steel is mainly used to manufacture springs that operate in high-temperature environments, such as those in automotive exhaust systems. This type of spring steel features high thermal strength and creep resistance, and can maintain stable mechanical properties at high temperatures.

5. Special-purpose spring steel:

According to specific application requirements, there are also some special-purpose spring steels, such as high-precision spring steels used for manufacturing precision instrument springs and soft magnetic spring steels used for manufacturing magnetic materials, etc.

Product Features of Spring Steel

1. High elastic limit:

Spring steel has an extremely high elastic limit, which means it can quickly return to its original shape after being subjected to external force without undergoing plastic deformation. This property makes spring steel an ideal material for manufacturing elastic elements such as springs.

2. Good fatigue resistance:

After being subjected to repeated stress, spring steel can still maintain the stability of its mechanical properties and is not prone to fatigue fracture. This is crucial for springs that need to withstand alternating loads for a long time.

spring steel coil figure

3. Excellent toughness and plasticity:

Spring steel exhibits excellent toughness and plasticity during processing, which makes it easy to bend, punch and stretch, thus meeting the requirements of various complex spring shapes and sizes.

4. Good heat treatment performance:

Spring steel usually has excellent heat treatment performance. Through heat treatment processes such as quenching and tempering, its hardness and strength can be significantly enhanced while maintaining good toughness.

5. Corrosion resistance:

Some spring steels undergo special treatments, such as galvanization or coating with anti-corrosion layers, which can enhance their corrosion resistance and extend their service life.

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