热处理工艺对AM355不锈钢力学性能的影响及机理

Effect and Mechanism of Heat Treatment on Mechanical Property of AM355 Steel

研究了改变热处理工艺对使用真空感应+电渣重熔工艺冶炼、经锻造成型的ψ80 mmAM355不锈钢棒的力学性能的改进及相关机理。试验结果表明,与传统热处理工艺(1 070℃×1 h空冷+(-70℃)×8 h+200℃×2 h空冷)相比,新的热处理工艺(1 000℃×1 h空冷+(-70℃)×8 h+450℃×2 h空冷+200℃×2 h空冷)可使ψ80 mm AM355不锈钢棒得到较高的强度和硬度,并保留一定的塑韧性。新的热处理工艺处理的AM355不锈钢棒的抗拉强度可提高120 MPa、屈服强度可提高400 MPa、硬度可提高5HRC,同时,冲击吸收功可保持大于40 J。对该钢棒经2种热处理工艺后产生的碳化物的类型和析出行为进行了观察研究之后指出,淬火温度对AM355不锈钢的晶粒度、碳化物类型及分布、残余奥氏体的转变都具有较大的影响,M23C6型碳化物的存在对钢的强化非常重要。

Different heat treatment process on AM355 steel bars were searched, which were produced by VIM＋ESR technique and forged into Ф80mm. Mechanical properties were tested after different quench temperatures, followed by same deep cold and different temperature. The results show that, with a contrast of traditional heat treatment （1 070 ℃× 1 h AC＋ （-70 ℃） × 8 h＋200 ℃× 2 h AC）, new heat treatment process （1 000 ℃ × 1 h AC＋ （-70 ℃）×8 h＋ 450 ℃ × 2 h AC ＋ 200 ℃× 2 h AC） can lead a rise of about 100 MPa in strength and 5HRC in hardness. Details of mechanical property are： Rm= 1 630 MPa, Re= 1 380 MPa, A = 16%, Z= 59%, impact energy 51 J, 50HRC. Sorts and precipitations of carbides in this AM355 bar were carried out by SEM and TEM, and strengthening mechanism were also searched. In conclusion, the quenching temperature has main effect on grain size, carbides, remained austenite, etc., and the exist of M23C6 carbide can lead a high strength.