Chemical composition of skt4 steel : C Si Mn Cr Ni Mo P S 0.50-0.60Â?¤0.40 0.50-0.80 0.50-0.80 1.40-1.80 0.15-0.30 Â?¤0.030 Â?¤0.030 Size: Round Diameter Length 50mm-500mm 2000mm-5800mm Steel plate Thickness Width Length 20-400mm 80-1000mm2000mm-5800mm Pre-hot treatment: 1.Annealing after forging:heat to 760-780â°c, keep 4-6h, furnace cold below 500â°c out and air cooling , hardness after annealing is 197-241hbs, 2.Isothermal after forging:heat to 850-870â°c, keep 4-6h, isothermal temperature680â°c, keep 4-6h, furnace cold below 500â°c Out and air cooling , hardness after forging is 197-241hbs. 3.Forging die renovation annealing:heat to 710-730â°c, keep 4-6h, furnace cool below 500â°c, out and air cooling, hardness After annealing is 197-241hbs. Characteristic 1.Good strength and high abrasion resistance 2.Good quenching Dongguan songshun mould steel co., ltd. Is located in changan town, dongguan city, china. After 10 years' development, Now we have the capacity to provide complete services from manufacturing and marketing to distributing. The main grades Of mould steel, tool steel and special steel which we market are listed as follows: