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在DIL805A/D相变仪上对试样进行热处理并测出相变点,应用余氏理论(EET)计算出相结构因子,并采用光学显微镜(OM)、透射电镜(TEM)及AMI-21型奥氏体测量仪对微观组织、亚结构及残留奥氏体量进行了观察与测量。分析了空冷条件下稀土对GDL-1钢连续转变的影响。结果表明:添加一定量稀土后,有τ/t<1,形成的核胚不会被侧向迁移的台阶吞并,可以激发形核长大,形成贝氏体多层次精细亚结构。稀土的添加使GDL-1钢中Fe-C-RE的偏聚单元增大(相结构因子nA和FCD值同时增大),造成Fe-C-RE偏聚结构单元对相变的阻力增加,抑制粒状贝氏体形成同时细化贝氏体铁素体组织及亚结构。稀土增加残留奥氏体量,且提高其稳定性。
The DIL805A / D phase change instrument was used to heat treat the sample and the phase transition point was measured. The phase structure factor was calculated by the theory of Yu ’s (EET). The optical microscopy (OM), transmission electron microscopy (TEM) and AMI - 21 Type austenite measuring instrument on the microstructure, substructure and residual austenite were observed and measured. The effect of rare earth on the continuous transformation of GDL-1 steel under air cooling condition was analyzed. The results show that there is τ / t <1 after a certain amount of rare earth is added, and the formed nuclei will not be swallowed up by the step of lateral migration, which can stimulate nucleation and growth and form multi-layer fine sub-structure of bainite. The addition of rare earth increases the segregation units of Fe-C-RE in GDL-1 steel (the values of phase structure factors nA and FCD increase at the same time), resulting in the increase of resistance to the phase transition of the Fe-C-RE segregation unit, Inhibit the formation of granular bainite and refine the bainitic ferrite structure and substructure. Rare earths increase the amount of retained austenite and improve its stability.