Cr元素及轧后控冷工艺对高强H型钢组织性能的影响

针对高强H型钢的开发,研究了Cr元素及轧后控冷工艺对高强H型钢组织性能的影响。利用Jmatpro软件、光学显微镜、ImagePro-Plus等试验方法对含Cr和不含Cr两种试验钢的奥氏体连续冷却转变(CCT)曲线,组织演变、力学性能及强韧化机制进行了研究。结果表明,随着冷速的增加,钢中铁素体和珠光体体积分数逐渐减小,当冷速达到一定时,钢中开始出现针状铁素体,且铁素体基体中有粒状贝氏体出现;Cr元素的加入,降低了奥氏体临界转变温度,抑制了铁素体和珠光体转变,并有效推迟了贝氏体转变。因此,含Cr钢更易于获得细小的铁素体组织且增加了贝氏体的形成倾向,有利于钢的强度尤其是抗拉强度的提升,但降低了其塑性和韧性。

Influence of Cr element and controlled cooling process after rolling on microstructure and mechanical properties of high strength H-beam

Aiming at the development ofhigh strength H-beam,the influence of Cr element and the controlled cooling process after rolling on the microstructure and properties of high strength H-beam was studied.Using Jmatpro software,optical microscope,ImagePro-Plus and other test methods,the austenite continuous cooling transformation (CCT) curve,microstructure evolution,mechanical properties and strengthening and toughening mechanism of the two test steels with Cr and without Cr were studied.The results show that as the cooling rate increases,the volume fraction of ferrite and pearlite in the steel gradually decreases.When the cooling rate reaches a certain level,acicular ferrite begins to appear in the steel,and there is granular bainite in the ferrite matrix.The addition of Cr element reduces the critical transformation temperature of austenite,inhibits the transformation of ferrite and pearlite,and effectively delays the transformation of bainite.Therefore,Cr-containing steel is easier to obtain fine ferrite structure and increases the tendency to form bainite,which is beneficial to the improvement of the strength of the steel,especially the tensile strength,but reduces its plastic toughness.