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通过光学显微镜、扫描电子显微镜、拉伸力学性能和冲击性能测试等手段,对比研究了Nb对汽车车身热轧板的显微组织和力学性能影响,探讨了Nb元素的作用机理。结果表明,在汽车车身板中添加一定含量的Nb元素可以显著细化晶粒,细化珠光体片层间距,并使珠光体片层更加平直;添加一定Nb元素后,热轧板的屈服强度和抗拉强度分别提高了37%和54%,断后伸长率和断面收缩率也有所提升,拉伸断口中韧窝更加细小、均匀,且深度更深;冲击性能提高了52.6%,这主要与细晶强化和第二相强化有关。
The effects of Nb on the microstructure and mechanical properties of automotive body hot rolled plates were studied by means of optical microscope, scanning electron microscopy, tensile mechanical properties and impact testing. The mechanism of action of Nb elements was also discussed. The results show that adding a certain amount of Nb into the automobile body plate can remarkably refine the grains, refine the spacing of the pearlite sheets and make the pearlite sheet more flat. After adding a certain Nb element, the yield of the hot rolled sheet The strength and tensile strength were increased by 37% and 54% respectively. The elongation at break and the reduction of area were also improved. The dimples in the tensile fracture were finer, more uniform and deeper, and the impact performance increased by 52.6% Related to fine grain strengthening and second phase strengthening.