冷却工艺对Q235低碳钢组织及性能的影响

Influence of Cooling Process on Microstructure and Mechanical Properties of Q235 Low Carbon Steel

将Q235B低碳钢奥氏体化后采用不同的方式进行冷却,得到不同类型的显微组织,然后测定了其力学性能,试验结果表明:实验钢930℃等温20 min后,随炉冷却得到铁素体和少量珠光体组织;空冷时出现大量的魏氏体,而淬火(水冷)形成板条马氏体。轧态、空冷和随炉冷却后的应力应变曲线虽然都有明显的屈服平台,但组织中存在粗大的多边形铁素体时加工硬化指数相对较高。淬火组织的应力应变曲线则表现为连续屈服。

Different microstructures have been obtained by means of different cooling process after austenization with hot rolled Q235 B steel,then the mechanical properties have also been measured. The experimental results demonstrates that：after isothermal holding at 930 ℃ for 20 min,followed by cooling in furnace,in air and quenched in water,the formation of ferrite with little pearlite,widmanstatten structure and martensite can be observed. The results of tensile testing show that the ε-σ curves of samples rolled,cooled in furnace and in air all have obvious yielding flat,and the presence of coarse polygonal ferrite is beneficial to obtain high processing hardening index,while the ε-σ curve of quenched sample is shown as continuous yield.