70 U20702 - GB /T 1222-2025

70 Chemical Element Composition Content (%)

Component	C	Si	Mn	P	S	Cr	Ni	Cu
Minimum Value	0.67	0.17	0.5	-	-	-	-	-
Maximum Value	0.75	0.37	0.8	0.025	0.02	0.25	0.35	0.2

70 Mechanical Properties

Heat Treatment or Condition	Tensile Strength σ_b Mpa	Specified Plastic Yield Strength Rp_0.2 Mpa	Elongation or Extension Rate δ %	Reduction of Area ψ %
Quenched in oil at 830±20°C and tempered at 480±50°C	≥1030	ReL ≥835	≥8	≥30

1 Approximate Comparison Table Spring Steel

China		United States		International Organization for Standardization	France	Russia	Sweden	United Kingdom
GB	ISC	AISI	UNS	ISO	NF EN/NF	GOST	SS₁₄	BS EN/BS
70	U20702	1070	G10700	Type DC	XC70	70	1778	070A72

2 Approximate Comparison Table High-Quality Carbon Structural Steel

3 Approximate Comparison Table High-Quality Carbon Structural Steel

4 Approximate Comparison Table Spring Steel

China		United States	International Organization for Standardization	European Standard
GB	ISC	ASTM/AISI	ISO	EN	Numerical Grade
70 (GB/T 1222-2016)	U20702	1070 (ASTM A29/A29M:2005)	DC (ISO 8458.3:1992)	C70D (EN 10016-2:1994)	1.0615

5 Approximate Comparison Table Spring Steel 1

70 Corresponding Standards(Same grade name, different standards)

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