Hardened Tempered Spring Steel Strips and Sheets

Hardened Tempered Spring Steel Strips

Spring steel is a type of steel that is specifically used to make springs, strippers, scrapers, and elastic parts because it can return to its original shape after bending, compression, or extension. This ability, known as elasticity in the quenched and tempered state, arises due to the high yield strength of the steel, which comes from its specific composition and hardening process. Fabricating spring steel requires advanced technical skills to ensure high quality. Any defects on the surface, such as decarburization or irregularities, can reduce fatigue strength. Baomit strip steel ensures that the springs have a perfectly smooth surface for optimal efficiency and performance.

Parameters	Recommendation
Thickness Tolerance	T2 – T3
Roughness	Class 3
Flatness	Class 3
Surface	Bright, White / Blue / Yellow Polished
Edges	Deburring, Square, Round
Hardness	44 – 52 HRC
Thickness	0.10 – 4.50 mm
Width	3 – 460 mm
Steel Grade	C67S, C75S, C100S, 50CrV4

Hardened and Tempered Stainless Steel Strips

Our Advantages:

• Excellent fatigue resistance

• Excellent punching and stamping properties

• Precise thickness and width tolerances

• Maximum straightness deviation of 1 mm / 6 m

• Good surface finish

• Consistent, uniform microstructure

Steel Grades

Comparison of Norms
EU / EN	USA / AISI	Chemical Composition
C67S	SAE1070	C: 0.65-0.73, Si: 0.15-0.35, Mn: 0.60-0.90, Ni: max 0.40, P: max 0.025, S: max 0.025, Cr: max 0.40, Mo: max 0.10
C75S	SAE1075	C: 0.60-1.20, Si: max 1.0, Mn: max 1.0, Ni: max 0.60, P: max 0.04, S: max 0.03, Cr: 16.0-18.0, Mo: max 0.75
50CrV4	SAE6150	C: 0.47-0.55, Si: max 0.40, Mn: 0.70-1.10, P: max 0.025, S: max 0.025, Cr: 0.90-1.20, V: 0.10-0.25

Manufacture Process

Cold Rolling

Slitting

Heat Treatment

Surface Polishing

Edging

Packaging

Thickness Tolerances

Thickness (mm)	Tolerances ± mm
Thickness (mm)	T1	T2	T3	T4	T5
0.020 – 0.040	0.004	0.003	0.002	–	–
0.040 – 0.100	0.006	0.005	0.004	0.003	0.002
0.100 – 0.125	0.007	0.005	0.004	0.003	0.002
0.125 – 0.160	0.009	0.006	0.005	0.004	0.003
0.160 – 0.200	0.010	0.007	0.005	0.004	0.003
0.200 – 0.250	0.011	0.008	0.006	0.004	0.003
0.250 – 0.400	0.015	0.011	0.008	0.006	0.004
0.400 – 0.600	0.020	0.014	0.010	0.007	0.005
0.600 – 0.800	0.023	0.017	0.012	0.008	0.006
0.800 – 1.000	0.027	0.019	0.013	0.009	0.007
1.000 – 1.250	0.034	0.024	0.017	0.012	0.008
1.250 – 1.600	0.039	0.028	0.020	–	–
1.600 – 1.750	0.046	0.033	0.023	–	–

Width Tolerances

Thickness (mm)	Width (mm)	Tolerances ± mm
Thickness (mm)	Width (mm)	W1	W2	W3
≤0.25	≤50	0.10	0.07	0.05
	50 – 125	0.15	0.11	0.07
	>125	0.20	0.15	0.10
0.25 – 0.50	≤50	0.15	0.11	0.07
	50 – 125	0.20	0.15	0.10
	>125	0.25	0.20	0.15
0.50 – 1.00	≤50	0.20	0.15	0.10
	50 – 125	0.25	0.20	0.15
	>125	0.30	0.25	0.15
1.00 – 1.60	≤50	0.20	0.15	0.10
	50 – 125	0.30	0.25	0.15
	>125	0.35	0.25	0.20
1.60 – 1.75	≤50	0.30	0.20	0.15
	50 – 125	0.35	0.30	0.20
	>125	0.40	0.30	0.20

Surface Roughness

Available in white polished, blue polished and yellow.

Thickness (mm)	Roughness
Thickness (mm)	Class 1	Class 2	Class 3
≤0.50	Ra≤ 0.30 µm Rt≤ 3.00 µm	Ra≤0.25 µm Rt≤ 2.50 µm	Ra≤ 0.20 µm Rt≤ 2.00 µm
0.50 – 1.00	Ra≤ 0.35 µm Rt≤ 3.50 µm	Ra≤ 0.25 µm Rt≤ 2.50 µm	Ra≤ 0.20 µm Rt≤ 2.00 µm
1.00 – 1.75	Ra≤ 0.40 µm Rt≤ 4.00 µm	Ra≤ 0.30 µm Rt≤ 3.00 µm	Ra≤ 0.30 µm Rt≤ 3.00 µm

Flatness Deviation

Maximum flatness deviation per inch strip width.

Thickness (mm)	Flatness Deviation
Thickness (mm)	Class 1	Class 2	Class 3	Class 4
0.02 – 0.10	P60	P50	P40	P30
0.10 – 0.25	P50	P40	P30	P20
0.25 – 0.50	P40	P30	P20	P10
0.50 – 1.75	P35	P25	P15	P10

Straightness Deviation

Strip Width (mm)	Measured Length (3m)
Strip Width (mm)	Class 1	Class 2	Class 3
≤50	3 mm	2 mm	1 mm
50 – 125	3 mm	2 mm	1 mm
>125	3 mm	2 mm	1 mm

Hubei Baomit Steel Materials Co., Ltd.

Leading manufacturer of hardened and tempered spring steel strips and sheets. Baomit strip steel stands for precision, quality and high performance. Our material is excellent in terms of comprehensive delivery indicators, such as straightness, flatness, mechanical properties and metallographic uniformity.