中碳伪共析钢在不同温轧温度下的组织与力学性能

Microstructure and mechanical properties on medium carbon pseudo-eutectoid steel at different warm rolling temperatures

为了强化普碳钢的力学性能,将经预处理后为伪共析组织的45钢,在不同温度(450、550和650℃)下温轧。利用扫描电镜、电子背散射衍射分析技术和拉伸试验的方法,研究中碳伪共析钢在温轧过程中的组织演变和力学性能。结果表明:试验钢温轧后得到的铁素体与珠光体组织呈多尺度层状分布,随着温轧温度的升高,渗碳体片层逐渐熔断、球化、长大并且分布趋于均匀。当温轧温度从450℃升高至650℃后,平均晶粒尺寸由0.34μm增大至0.59μm,抗拉强度由1424 MPa下降至1013 MPa,伸长率由5.5%升高至7.0%。在550℃温轧时强度和塑性达到最优组合,强塑积最高,为8350 MPa·%。研究结果表明,通过构筑多尺度层状异质结构,可在一定程度上强化普碳钢的力学性能。

In order to strengthen the mechanical properties of plain carbon steel,45 steel with pseudo-eutectoid structure after pretreatment was warm rolled at different temperatures(450,550 and 650℃),and the microstructure evolution and mechanical properties of medium carbon pseudo-eutectoid steel during the warm rolling process were studied by means of scanning electron microscope,electron backscattered diffraction analysis and tensile test.The results show that the microstructure of ferrite and pearlite obtained after the warm rolling of test steel is multi-scale layered distribution.With the increasing of warm rolling temperature,the cementite lamellae gradually fuses,spheroidizes,grows up and distributes evenly.When the warm rolling temperature increases from 450℃to 650℃,the average grain size increases from 0.34μm to 0.59μm,the tensile strength decreases from 1424 MPa to 1013 MPa,and the elongation increases from 5.5%to 7.0%.When the warm rolling temperature is 550℃,the strength and plasticity achieve the optimal combination,and the product of strength and plasticity is the highest,which is 8350 MPa·%.This research results show that the mechanical properties of plain carbon steel can be strengthened to a certain extent by constructing multi-scale layered heterostructures.