高合金超高强度钢锻件的退火工艺
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摘要
针对高合金钢锻后冷却和退火过程中的开裂问题,研究了M54高合金超高强度钢高温奥氏体化后冷却过程中的相变,以及相变产物对硬度、塑性和韧性的影响,并据此评价锻件冷却和回火过程中的开裂倾向。结果表明,M54钢高温奥氏体化后空冷到室温,随后630℃退火硬度最低,塑性和韧性最好,以此判定实际生产锻件从高温需冷透后再进行退火,锻件开裂的倾向最小,如果退火之前未完全冷透则使材料极度脆化,锻件开裂的倾向最大;高温奥氏体化后直接进入630℃炉内保温不仅不能降低硬度,反而弱化了晶界降低塑性和韧性,因此锻后进入630℃炉内保温同样增大锻件开裂倾向。
In view of cracking problem of high alloy steel M54 in the process of cooling after forging and annealing,the phase transformation in the cooling process after high temperature austenitizing,and the influence of phase transition products on hardness,plasticity and toughness of the steel was studied,and accordingly the forging cracking tendency during cooling and tempering was evaluated. The results show that the steel can get the lowest hardness and highest ductility and toughness when cooled to room temperature after high temperature austenitizing and followed by annealing at 630 ℃. Hence,it can be deduced that the forging should have the lowest cracking tendency if it is cooled to room temperature from high temperature in actual production and followed by annealing. If the cooling is not completely finished before annealing,which will make the steel extremely become embrittle and show the highest cracking tendency. When directly annealed at 630 ℃ after high temperature austenitizing,the hardness of the steel can't be decreased,but the grain boundary will be weaken and both the ductility and toughness will be lowered. Therefore,630 ℃ annealing after forging without cooling to room temperature also increases the cracking tendency.
In view of cracking problem of high alloy steel M54 in the process of cooling after forging and annealing,the phase transformation in the cooling process after high temperature austenitizing,and the influence of phase transition products on hardness,plasticity and toughness of the steel was studied,and accordingly the forging cracking tendency during cooling and tempering was evaluated. The results show that the steel can get the lowest hardness and highest ductility and toughness when cooled to room temperature after high temperature austenitizing and followed by annealing at 630 ℃. Hence,it can be deduced that the forging should have the lowest cracking tendency if it is cooled to room temperature from high temperature in actual production and followed by annealing. If the cooling is not completely finished before annealing,which will make the steel extremely become embrittle and show the highest cracking tendency. When directly annealed at 630 ℃ after high temperature austenitizing,the hardness of the steel can't be decreased,but the grain boundary will be weaken and both the ductility and toughness will be lowered. Therefore,630 ℃ annealing after forging without cooling to room temperature also increases the cracking tendency.
引文
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[3]邹伟龙,王毛球,时捷,等.热处理对25CrNi3MoV钢组织与力学性能的影响[J].金属热处理,2008,33(7):69-72.Zou Weilong,Wang Maoqiu,Shi Jie,et al. Influence of heat treatment on miscrostructure and mechanical properties of 25CrNi3MoV steel[J].Heat Treatment of Metals,2008,33(7):69-72.
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