65Mn GB /T 699-1999 Spring wire

Material designation	65Mn
China ISC	U21652
Correspondence standard	GB /T 699-1999 Quality Carbon Structural Steels
Sort out	Carbon steel
property	Strength elastic resistance to fatigue
Tag	Spring steel
Instructions	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 canmake spring washer,slotted elastic cylindrical pin,open retaining ring and other standard parts. This standard applies to high-quality carbon structural steel bars with a diameter or thickness not greater than 250mm,and can also provide high-quality carbon structural steel bars with a diameter or thickness greater than 250mm after negotiation between the supply and demand parties.

65Mn_GB Spring_wire

65Mn Chemical element content (%)

Ingredient	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

① The grades listed in the table are high quality steel. High quality steel, in the grade suffix A, the last digit of the unified digital code is changed to 3; Super high quality steel, in the grade suffix E, the last digit of the unified digital code is changed to 6; Boiling steel, grade suffix F, the last digit of the unified digital code is changed to 0; Semi-killed steel, grade suffix b, unified number code last digit is 1

High-quality steel P≤0.035%,S≤0.035%

High quality steel P≤0.030%,S≤0.030%

Super high quality steel P≤0.025%,S≤0.020%

② 08 steel with aluminum deoxidation smelting killed steel, the lower limit of manganese content is 0.25%, silicon content is not more than 0.03%, aluminum content is 0.02%~0.07%, this time the steel grade is 08Al

③ By agreement between the supply and demand parties, 08~25 steel can supply semi-killed steel with silicon content not more than 0.17%, and its grade is 08b~25b

④The allowable copper content of steel smelted with scrap steel is not more than 0.30%; The copper content of steel for hot pressure processing should not be greater than 0.20%

⑤The silicon content of boiling steel for cold stamping should not be greater than 0.03%

⑥The nitrogen content of steel smelted by oxygen converter should not be greater than 0.008%

65Mn mechanical properties

Diameter (thickness) d mm	Strength of extension σb Mpa	Yield point σs Mpa	Elongation or elongation after breaking δ %	Hardnessl HBW
d=25(sample size)	normalizing ≥735	normalizing ≥430	normalizing ≥9	Unheat treated steel≤285
				Annealedsteel≥229

①For steel with a diameter or thickness of less than 25mm, the heat treatment is carried out on a sample blank with the same cross-section size as the finished product.

②Table normalizing recommended holding time is not less than 30min, air cooling; The recommended holding time for quenching is not less than 30min, 70, 80 and 85 steel oil cooling, and the rest steel water cooling; The recommended holding time for tempering is not less than 1h.

ⓐ Delivery status of unheat treated steel Delivery hardness HBS10/3000 data is shown in the first row of the table; Annealed steel hardness HBS10/3000 data are shown in the second row of the table

ⓑHeat treatment of steel samples: normalizing temperature 830°C

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