65Mn GB /T 699-2015 Carbon steel wire

Material designation	65Mn
China ISC	U21652
Correspondence standard	GB /T 699-2015 Quality carbon structure steels
classify	carbon steel
performance	Elastic fatigue resistance
label	spring steels
explain	After heat treatment and cold drawing hardening, the strength is high, with certain toughness and plasticity; Under the same surface state and full quenching condition, the fatigue limit is similar to that of alloy springs. However, the hardenability is poor, mainly used for smaller size springs, such as pressure regulating spring, force measuring spring, general mechanical round, square coil springs or drawn steel wire for small mechanical springs. It can make spring washer, slotted elastic cylindrical pin, open retaining ring and other standard parts This standard applies to hot rolled and forged high-quality carbon structural steel bars with nominal diameter or thickness not greater than 250mm, and can also provide hot rolled and forged high-quality carbon structural steel bars with nominal diameter or thickness greater than 250mm after negotiation between the supply and demand parties.
density	7.81 g/cm3

65Mn Chemical element content (%)

Component	C	Si	Mn	P	S	Cr	Ni	Cu
Minimum value	0.62	0.17	0.9	-	-	-	-	-
Maximum value	0.7	0.37	1.2	0.035	0.035	0.25	0.3	0.25

65Mn mechanical properties

Diameter (thickness) d mm	Heat treatment or condition	strength of extension σb Mpa	yield point σs Mpa	Elongation or elongation after breaking δ %	Shrinkage of section ψ %	Hardness HBW
d=25(sample size)	normalizing	≥735	≥430	≥9	≥30	Unheat treated steel ≤285
						Annealed steel ≤229

ⓐ The mechanical properties in the table are applicable to steel rods with a nominal diameter or thickness not greater than 80mm.

ⓑFor steel rods with nominal diameter or thickness greater than 80~250mm, the elongation after fracture and the shrinkage of section are allowed to be reduced by 2% (absolute value) and 5% (absolute value), respectively, compared with the provisions of this table.

ⓓ When the size of the steel rod is less than the blank size, the full size steel rod is used for heat treatment.

ⓔ When the yield phenomenon is not obvious, the specified plastic extension strength Rp0.2 can be used instead

* Recommended heat treatment temperature: normalizing temperature 830°C±30°C; Recommended holding time: normalizing no less than 30min, air cooling.

Physical properties

Elastic modulus E/GPa				Shear modulus G/GPa				Specific Heat Capacity c/J·(g·K)-1
Elastic modulus E/GPa				Shear modulus G/GPa				Specific Heat Capacity c/J·(g·K)-1
20℃	100℃	300℃	500℃	20℃	100℃	300℃	500℃	20℃
211	-	-	208.9	83.67	-	81.56	82.97	0.481
211	-	-	208.9	83.67	-	(400°C)	82.97	(200°C)
Thermal conductivity λ/W·(m·K)				Linear expansion coefficient α/10-6 ·K-1				Resistivity ρ/ 10-6Ω ·m
20℃	100℃	300℃	500℃	20℃	20～200℃	20～400℃	20～600℃	20℃
-	-	-	-	-	11.1 (20~100°C)	12.9 (20~300°C)	14.6	-

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