70,75 high-quality carbon structural steel - Alloy structural steel

Chemical composition:

Trademark	Chemical composition
	C	Si	Mn	P	S	Ni	Cr	Cu
	C	Si	Mn	≤
70	0.67～0.75	0.17～0.37	0.50～0.80	0.035	0.035	0.30	0.25	0.25
75	0.72～0.80	0.17～0.37	0.50～0.80	0.035	0.035	0.30	0.25	0.25

Mechanical properties:

Trademark	The sample blank Size / mm	Heat treatment process			Mechanical properties					Delivery status hardness of steel / HBS
		Normalizing	Quench	Tempering	σ_b/MPa	σ_s/MPa	δ₅(％)	ψ(％)	A_k/J	≤
		Normalizing	Quench	Tempering	≥					Without heat treatment	Annealed steel
70	25	790			715	420	9	30		269	229
75	试样		820	480	1080	880	7	30		285	241

Characteristics and Uses:
70: 65 strength and elasticity than steel pins high, similar to other properties. Low hardenability, spring steel wire diameter of more than 12-15mm can not hardenability, not only for the manufacture of the spring cross-section, and the wheel ring.
75: 65 # steel with similar performance, its flexibility somewhat less than 65 gauge steel, high strength, low hardenability, quenching and tempering in the state of general use. Not used in the manufacture of high strength, cross-sectional dimensions smaller spiral springs, plate springs, mechanical parts subject to wear.