热处理对双真空冶炼AISI 4340钢显微组织和拉伸性能的影响  

Effect of heat treatment on microstructure and tensile properties of double vacuum smelting AISI 4340 steel

作　　者：潘权文 颜莹 李小武 王斌[2] 张鹏[2] 张哲峰[2] PAN Quan-wen;YAN Ying;LI Xiao-wu;WANG Bin;ZHANG Peng;ZHANG Zhe-feng(Department of Materials Physics and Chemistry,School of Materials Science and Engineering,Northeastern University,Shenyang 110819,China;Institute of Metals Research,Chinese Academy of Science,Shenyang 110016,China)

机构地区：[1]东北大学材料科学与工程学院材料物理与化学系,辽宁沈阳110819 [2]中国科学院金属研究所,辽宁沈阳110016

出　　处：《材料热处理学报》2021年第4期87-95,共9页Transactions of Materials and Heat Treatment

基　　金：国家自然科学基金青年基金项目(52001310);中国博士后科学基金面上项目(2020M670810)。

摘　　要：采用光学显微镜、透射电镜和拉伸实验等研究了不同热处理状态的双真空冶炼AISI 4340钢的显微组织与拉伸性能,并与普通冶炼AISI 4340钢的强度-塑性进行对比。结果表明:淬火态双真空冶炼AISI 4340钢的微观组织主要由板条和片层孪晶马氏体组成,板条内位错密度较高;经350℃回火后有大量碳化物析出,且仍观察到片层孪晶马氏体;随着回火温度继续升高,逐渐形成回火索氏体。随着回火温度升高,双真空冶炼AISI 4340钢中片层孪晶马氏体逐渐分解消失以及板条内位错密度下降导致其强度降低,而析出碳化物的球化则是塑性提高的主要原因。与普通冶炼工艺相比,双真空冶炼显著降低了AISI 4340钢中夹杂物含量,从而提高其塑性;淬火态和350℃回火态双真空冶炼AISI 4340钢强度-塑性同步提高的一个原因是纳米级片层孪晶马氏体的存在。Microstructure and tensile properties of double vacuum smelting AISI 4340 steel with different heat treatments were studied by means of optical microscope, transmission electron microscopy and tensile experiment, and compared with the strength-plasticity of ordinary smelting AISI 4340 steel. The results show that the microstructure of the quenched double vacuum smelting AISI 4340 steel is mainly composed of lath and lamellar twin martensite, and the dislocation density in the lath is high. After tempering at 350 ℃, a large number of carbides precipitate, and the lamellar twin martensite is still observed. As the tempering temperature continues to increase, tempering sorbite is gradually formed. With the increase of the tempering temperature, the twin martensite in the double vacuum smelting AISI 4340 steel gradually decomposes and disappears, and the dislocation density in the lath decreases, resulting in the decrease of the strength of the steel, while the spheroidization of the precipitated carbides is the main reason for the improvement of its plasticity. Compared with the ordinary smelting process, the double vacuum smelting significantly reduces the content of inclusions in the AISI 4340 steel, thus improving its plasticity. One of the reasons why the strength and plasticity of the AISI4340 steel prepared by double vacuum melting increase at the same time after quenching and 350 ℃ tempering is the existence of nanoscale lamellar twin martensite.

关 键 词：AISI 4340钢 双真空冶炼 热处理 显微组织 拉伸性能 

分 类 号：TG142.3[一般工业技术—材料科学与工程]