Nitriding nitriding surface tissue obtained in high hardness, surface hardness after nitriding reach 650-700HV (57-60HRC) die life can reach more than one million times, the nitride layer having a dense SKH-55 hardness, smooth characteristics mold releasing property and anti-corrosive wet air and the lye can be improved. Hardening process to improve die life up to 80 million times more SKH-55, can be pre-hardened steel quenched and tempered low and hard ways. Preheated quenching at 500-600 ℃ 2-4 hours and then at 850-880 ℃ holding a certain time (at least 2 hours) SKH-55 high-speed steel, into the oil cooled to 50-100 ℃ oil cooled, hardened After the hardness up to 50-52HRC, to prevent cracking should be 200 ℃ tempering treatment immediately after tempering, the hardness can be maintained over 48HRC or metal forging die casting mold, requires a very low surface roughness. Once this type of mold thermal fatigue cracks, it can not continue in service. Therefore, these service life of the mold, mainly determined by the thermal fatigue crack initiation time for ordinary die allows a certain size thermal fatigue cracks. Thus, the life of the mold, depending on the thermal fatigue crack initiation and propagation speed at the time when the cold extrusion of metal black, thermal effects due to the severe deformation of the metal flow generated by the mold temperature, sometimes up to 150 ^ 4000C. Mold cyclical temperature changes may also cause thermal fatigue cracking and failure SKH-55 material, Zhuhai SKH-55, Yong Wei steel mold provided by the Dongguan City An Yongwei steel mold shop. Dongguan City An Yongwei mold steel shop (www.dgyongwei.com) strong, credible, in Dongguan, Guangdong special steel industry has accumulated a large number of loyal customers. The company better work attitude and continuous improvement AsiaVest innovative ideas will lead you hand into the mold steel and brilliant for a better future!