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采用XRD和TEM研究了低碳低合金相变诱导塑性(TRIP)钢在单向拉伸状态下的组织转变特性。用Rietveld方法拟合分析了不同应变量下TRIP钢中残余奥氏体(RA)的含量。结果表明,试验中TRIP钢中RA转变量(RA→M)随塑性应变量的增大而增加。TRIP钢变形前的组织为铁素体、贝氏体和残余奥氏体,残余奥氏体主要以晶间薄片状、块状和位于铁素体晶内的细小颗粒状三种形态存在。经拉伸变形后,晶间块状或薄片状RA在应力作用下转变为孪晶结构的马氏体,铁素体晶内的细小颗粒状RA则未发现马氏体相变,但其周围会塞积高密度位错。
XRD and TEM were used to investigate the microstructure and transformation characteristics of low carbon and low alloy transformation induced plasticity (TRIP) steel under uniaxial tension. The content of retained austenite (RA) in TRIP steel under different strain levels was fitted by Rietveld method. The results show that the amount of RA change (RA → M) in TRIP steel increases with the increase of plastic strain. The microstructure of TRIP steel before deformation is ferrite, bainite and retained austenite. The residual austenite exists mainly in the form of intergranular flake, massive and fine granular in ferrite crystal. After tensile deformation, intergranular massive or flaky RA transformed to martensite with twinstructure under the action of stress, while the fine granular RA in ferrite crystal did not find the martensitic transformation, but the surrounding Will plug the plot of high-density dislocations.