Effect of N on Mirostructures and Mechanical Properties of Vanadium Containing Q345 Steel
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摘要: 试验钢为含钒0.080%的Q345钢，氮含量按0%、0.022%、0.034%、0.042%逐渐升高。利用Thermo-Calc软件进行了热力学分析计算，结果表明：钢中不含氮时，V （C，N）在奥氏体中析出温度较低，为933℃，当钢中氮含量为0.042%时，在奥氏体中析出温度1 340℃。通过透射电镜，可以发现含钒Q345钢随着氮含量增高，钢中析出了大量的V （C，N）弥散在钢中，起到析出强化作用和细化晶粒作用。金相组织得到明显细化。增氮后钢的力学性能得到明显增强，不含氮时试验钢的屈服强度486 MPa，抗拉强度686 MPa，当氮含量为0.034%时，试验钢的屈服强度为610 MPa，抗拉强度732 MPa，钢的屈服强度提高了124 MPa。抗拉强度提高了46 MPa。并且通过拉伸断口判断，随着氮含量的增加，Q345钢的塑韧性得到增强。
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关键词:
- Q345钢 /
- Thermo-Calc软件 /
- V (C,N)析出 /
- 力学性能
Abstract: The test steels in this study had base chemistry of Q345 steel with 0.08%V and various nitrogen contents of 0%, 0.022%,0.034% and 0.042%.Thermo-Calc software was used for the thermodynamic calculation.When steel is free of nitrogen,the calculated V(C,N) precipitation temperature in austeniteis 933℃.When the nitrogen content in the steel is 420×10-6.the precipitation temperature of V(C,N) is 1 340℃.TEM observation indicates that increasing nitrogen content can result in a large number of V(C,N) which plays the role of precipitation strengthening and refining grain.The mechanical properties of the steel increase significantly with increasing nitrogen content.The steel free of nitrogen has yield strength of 486 MPa,and tensile strength of 686 MPa.When the nitrogen content is 340×10-6,the yield strength of the test steel is 610 MPa,and the tensile strength is 732 MPa.Fracture observation show that toughness and ductility of Q345 steel has been enhanced with increase of nitrogen content.-
Key words:
- Q345 steel /
- Thermo-Calc software /
- V (C,N) precipitation /
- mechanical property
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