二T乙到拓背 弹簧钢材质锻造 整体热处理/无毛刺/不伤手高精度/高弹性 OVERALL HEAT TREATMENT /NO BURR/NO HAND INJURY/HIGH PRECISION /HIGH ELASTICITY 号 号 0Z0 0.07 9z0 0.06 0.05 0v0 0.04 090 0.03 0.02 92'0 1.00