煤矿机械制造厂一般都采用5CrMnMo钢制造中小型热锻模具,传统的热处理工艺是850℃加热油淬,380～540℃回火。为防止模具变形和开裂,油淬至略低于钢的M_s点即行出油。此时,心部仍处于过冷奥氏体状态,立即转入380～540℃的回火炉中回火,心部组织主要转变成以上贝氏体为主的组织,引起所谓“贝氏体脆性”,造成模具的早期脆断,寿命不高。如改用复合等温淬 Coal mining machinery manufacturers generally use small and medium 5CrMnMo steel hot forging die, the traditional heat treatment process is 850 ℃ heating oil quenching, 380 ~ 540 ℃ tempering. To prevent mold deformation and cracking, the oil is quenched to a point slightly below the M_s point of the steel. At this point, the heart is still in the supercooled austenitic state, immediately transferred to the tempering furnace 380 ~ 540 ℃ tempering, the heart tissue mainly into the above bainite-based organizations, causing the so-called “bainitic brittle ”, Resulting in early brittle fracture mold, life expectancy is not high. Such as switch to compound isothermal quenching