OT Wire

OT Wire containing C, Si is selectively added by the predetermined amounts of V, Cr, and Cu. our OT Wire shows ecellent performance which is not available in high carbon spring wire and music wire. OT Wire has superior strength and toughness. It will implement excellent elasticity, ductility, better resistance against fatigue and deformation in various spring applications. OT Wire is recommended to make the springs for repeated dynamic loads, including clutch springs.

1. Classification, code, diameter range of steel wire and the corresponding relationship with steel grade

Classification		Static state	Medium fatigue	High fatigue	Grade
Tensile Strength	Low Strength	FDC	TDC	VDC	65、70、65Mn
	Medium Strength	FDCrV（A、B）	TDCrV（A、B)	VDCrV（A、B）	50CrVA、67CrV
	Medium Strength	FDSiMn	TDSiMn		60Si2Mn、60Si2MnA
	High Strength	FDCrSi	TDCrSi	VDCrSi	55CrSi、SAE9254V
Diameter		0.5mm~17.0mm	0.5mm~17.0mm	0.5mm~10.0mm
Note 1: Static grade steel wire is suitable for general purpose spring, which is expressed as FD, Note 2: medium fatigue grade steel wire is suitable for clutch spring, suspension spring, shock absorbing coil spring, etc., which is expressed as TD. Note 3: High fatigue grade steel wire is used in the occasion of intense movement, such as engine valve spring, valve spring, expressed as VD.

2. Steel wire diameter control range

Diameter(mm)	Tolerance（±）		Diameter(mm)	Tolerance（±）
Diameter(mm)	TD VD	FD		TD FD	VD
0.50 - 0.80	0.01	0.015	5.50 - 7.00	0.035
0.80 - 1.00	0.015	0.02	7.00 - 9.00	0.035
1.00 - 1.80	0.02	0.025	9.00 - 10.00	0.04
1.80 - 2.80	0.025	0.03	10.00 - 11.00	0.04
2.80 - 4.00	0.03		11.00 - 14.50	0.05
4.00 - 5.50	0.03		14.50 - 17.00	0.05

Note: The non-roundness is not more than half of the allowable deviation of the size

3. Steel wire surface inspection

The surface of the steel wire is smooth, and there should be no scratches, rust, folding, stuttering and other defects that may have harmful effects on the use of the steel wire. The maximum depth is allowed to not exceed the bottom

Table specifies depth of defects. VD grade, TD grade steel wire shall not be fully decarbonized, but allow not more than d1.0% of the partial decarbonization.

The maximum depth allowed for surface defects

Diameter(mm)	VD	TD	FD
0.50~2.00	0.01mm	0.015mm	0.02mm
2.00~6.00	0.5%d	0.8%d	1.0%d
6.00~10.10	0.7%d	1.0%d	1.4%d
10.00~17.00	-	0.10mm	0.20mm

4. Heat treatment
After coiling, the spring should be tempered between 380 ° C and 420 ° C to reduce the surface stress, and after shot blasting, it should be hot pressed or stress relieved at 250 ° C.

5. Delivery status
Oil hardening-tempering

6. Delivery form
The steel wire is delivered in coil form

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