钛含量对0.17C-0.30Si-1.40Mn钢组织与力学性能的影响

Effect of titanium content on the microstructure and mechanical properties of 0.17C-0.30Si-1.40Mn steel

在某钢厂冶炼的0.17C-0.30Si-1.40Mn钢中添加不同含量的微合金化元素钛,热连轧成板卷后逐卷取样进行力学性能测试和金相组织检验,并采用碳复型萃取方法制作薄膜样品进行透射电镜观察,研究了钛含量对0.17C-0.30Si-1.40Mn钢组织和力学性能的影响。结果表明:随钢中钛含量由0增加至0.073%,当Ti含量≤0.020%时,强度缓慢提高;当Ti含量为0.021%~0.038%时,强度显著提高;当Ti含量>0.038%时,强度增加趋缓。钛加入0.17C-0.30Si-1.40Mn钢越多,钢的延伸率和冲击功下降就越多。钛对0.17C-0.30Si-1.40Mn钢的显微组织影响不大,仅能使其晶粒尺寸略微减小。钛在0.17C-0.30Si-1.40Mn钢中只能沉淀析出少量尺寸较大的Ti(N,C)和TiCS颗粒,起到微弱的细晶强化作用,但是钛在钢中能够沉淀析出大量细微的TiC颗粒,产生强烈的沉淀强化作用。此外,研究发现钛含量对低碳锰钢力学性能的影响还与钢中碳含量有关,钢中碳含量不同,强度随钛含量转变曲线上的2个拐点也不相同。

0.17C-0.30Si-1.40Mn steels with different titanium contents were prepared by smelting process.After hot rolling into hot-rolled coils,samples were taken for mechanical property test and metallographic structure inspection.Thin-film samples were made by the carbon replica extraction method for transmission electron microscope observation.The effect of titanium content on the microstructure and mechanical properties of 0.17C-0.30Si-1.40Mn steel was studied.The results show that the strength evolution corresponds to the Ti content (from 0 to 0.073%).The strength increases slowly when the Ti content is less than 0.020%,subsequently the strength increases significantly when the Ti content is 0.021%-0.038%,finally,the strength increases slowly again when the Ti content is more than 0.038%.The more titanium is added into 0.17C-0.30Si-1.40Mn steel,the more the elongation and impact energy decrease.Titanium has little effect on the microstructure of 0.17C-0.30Si-1.40Mn steel and can only slightly reduce its grain size.A small amount of Ti(N,C) and Ti_(4)C_(2)S_(2) particles of large size can be precipitated in 0.17C-0.30Si-1.40Mn steel,which weakly plays a fine-grain strengthening;however,a large number of fine TiC particles can be precipitated in the steel,resulting in strong precipitation strengthening effect.It is found that the influence of titanium content on the mechanical properties of low carbon manganese steel is also related to the carbon content in the steel.The two inflection points of the curve about strength transformation with titanium content also vary with different carbon content in the steel.Thereby restraining martensitic phase transformation.