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利用热变形和两步淬火配分(quenching and partitioning,Q&P)工艺的复合作用制备低碳合金钢试样,设计不同的热变形温度,研究加载(获得30%变形量)引起的应力和塑性变形对Q&P工艺下马氏体相变开始温度(Ms),残余奥氏体含量和力学性能的影响.结果表明,与传统两步Q&P工艺相比,复合作用下显微组织细化,尤其是随着变形温度的降低细化更明显,马氏体板条呈现弯曲形貌.随着变形温度升高,Ms升高,但马氏体转变量却有所下降,其原因是应力引起的位错多在奥氏体母相晶界处出现,成为马氏体相变优先形核的位置,而一旦发生相变,一定的塑性应变将提高晶内奥氏体的稳定性,从而促进残余奥氏体含量增加.复合作用下试样的力学性能也有所提高,在650℃变形时试样的硬度最高,而在750℃变形时试样的塑性最好.
Low-carbon alloy steel samples were prepared by the combination of thermal deformation and quenching and partitioning (Q & P) processes. Different heat distortion temperatures were designed to study the stress and plastic deformation caused by loading (30% deformation) Q & P process on martensitic transformation temperature (Ms), residual austenite content and mechanical properties were studied.The results show that the microstructure is refined under the combined effect of the two-step Q & P process, especially with the deformation The decrease of temperature is more obvious, and the martensite lath shows a curved appearance. Ms increases with the increase of deformation temperature, but the amount of martensite transformation decreases due to the stress-induced dislocations The austenite parent phase appears at the grain boundary and becomes the nucleation site of martensite phase transformation. Once the phase transformation occurs, a certain plastic strain will increase the stability of the austenite in the crystal and promote the retained austenite content Increase.The mechanical properties of the composite under the composite effect also increased, the highest hardness of the sample deformation at 650 ℃, and the plastic deformation of the sample at 750 ℃ the best.