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采用光学显微镜、扫描电镜、纳米力学探针、透射电镜等技术对不同Si含量(0.03%和1.077%)的DP600级别热轧双相钢单向拉伸过程组织特征进行研究,分析了Si含量对相同工艺条件下双相钢显微组织特征,以及塑性变形过程中强化相与基体协调变形行为的影响。结果表明:Si作为一种铁素体形成元素,能够增加铁素体的形核率,具有细化铁素体晶粒的作用,可增加铁素体体积分数,分割并细化马氏体。Si含量的增加促进了C元素向马氏体富集,提升了单位体积马氏体的碳含量,使部分板条马氏体转变为孪晶马氏体,增加了马氏体硬度。由于Si对铁素体的净化作用,高Si实验钢中位错在铁素体中滑移时不易受到碳化物的钉扎作用。因此在相同工艺条件下,Si含量的增加可以提高双相钢的抗拉强度,提高硬度,降低屈强比。
The microstructures of DP600 hot rolled duplex stainless steel with different Si contents (0.03% and 1.077%) were investigated by optical microscopy, scanning electron microscopy, nanomechanical probe and transmission electron microscopy. The effects of Si content Under the same process conditions, the microstructures of the dual phase steel and the influence of the strengthening phase and the matrix in the process of plastic deformation were studied. The results show that Si, as a kind of ferrite, can increase the nucleation rate of ferrite, refine the ferrite grains, increase the ferrite volume fraction, and cut and refine the martensite. The increase of Si content promotes the enrichment of C into martensite, increases the carbon content per unit volume of martensite, transforms part of lath martensite into twin martensite and increases the martensitic hardness. Due to the purifying effect of Si on ferrite, dislocations in high-Si experimental steels are not susceptible to pinning of carbides during slippage in ferrite. Therefore, under the same process conditions, the increase of Si content can improve the tensile strength of dual phase steel, increase the hardness and reduce the yield ratio.