... important and working temperature < 300 spring °C valve spring, the pistons spring, the relief valve spring 2.Chemical ingredients: Carbon C: 0.47 ~ 0.55Si Si ... : Heat treatment specification: quenching 850 °C ± 20 °C, oil cold; Tempering 500 °C ± 50 °C (special needs, 30 °C ±).5.Delivery status:the hot rolling ...