N含量对Ti微合金化低碳马氏体钢力学性能的影响

Effect of nitrogen content on mechanical properties of Ti-microalloyed low carbon martensite steel

采用SEM、EDS、拉伸及冲击试验、热力学分析等方法,对两种具有不同N含量的Ti微合金化低碳马氏体钢的组织与力学性能进行分析。结果表明:N含量对Ti微合金化低碳马氏体钢强度影响不大,但明显影响其韧性,1号试验钢(N含量0.0054%)和2号试验钢(N含量0.0014%)上平台冲击吸收能量分别为30 J和70 J。1号试验钢微观组织及冲击断口中存在大尺寸的Ti N析出相,很容易使得试验钢中Ti N与基体结合界面产生微米级裂纹,从而显著降低断裂强度和韧性。

Microstructure and mechanical properties of two different Ti-microalloyed low carbon martensite steels with different nitrogen content were investigated by means of scanning electron microscopy（ SEM）,energy dispersive spectrometer（ EDS）,tensile and impact test,thermodynamic analysis. The results show that effect of nitrogen content on strength of Ti-microalloyed low-carbon martensite steels is not obvious,however,its effect on toughness is significant. The upper shelf impact absorbed energy of No. 2 steel（ 0. 0014% N） and No. 1 steel（ 0. 0054% N） is 70 J and 30 J,respectively. Large particle Ti N can be found in the microstructure and fracture morphology of No. 1 steel which can easily induce the micron sized crack along the phase boundary and reduce the fracture stress and toughness obviously.