本工作研究了普通304不锈钢(CPSS-304)和深度轧制备技术制备的纳米晶304不锈钢板材(NSSP-304) 3个相互垂直面的显微硬度。利用XRD、TEM和EBSD等方法表征了NSSP-304和CPSS-304微观组织。NSSP-304 3个面的显微硬度均大于CPSS-304且显微硬度分布更均匀。NSSP-304轧制面显微硬度比其他2个面的显微硬度高约40 HV,这与其织构({110}<211>)有关。NSSP-304 0.5 mol/L HCl 溶液中室温恒电位极化,腐蚀速率及其随极化时间的变化范围都小于CPSS-304;6% FeCl3 (质量分数,35℃)溶液浸泡过程中,NSSP-304腐蚀速率及其变化幅度都低于CPSS-304。2种溶液中,NSSP-304点腐蚀孔的密度和尺寸都小于CPSS-304。这些研究结果表明,尽管NSSP-304制备过程中发生严重的形变(总形变量大于70%)且产生织构、形变孪晶和高密度位错,但是NSSP-304在2种腐蚀溶液中均匀和点腐蚀阻力都高于CPSS-304。NSSP-304显微硬度和耐腐蚀性能同时提高,是由于NSSP-304晶粒细化、形变孪晶、高的位错密度和高的小角角度晶界含量形成的价电子结构不同于CPSS-304。
The microhardness of nanocrystalline 304 stainless steel plate (NSSP-304) produced by severe rolling technology and its counterpart of the conventional polycrystalline 304 stainless steel (CPSS-304) were investigated on the three planes perpendicular to each other. The microstructures of NSSP-304 and CPSS-304 were characterized using an X-ray diffractometer (XRD), a transmission electron microscope (TEM) and an electron backscatter diffraction (EBSD). The microhardness values on the three planes of NSSP-304 are larger than those of CPSS-304, which has nothing to do with martensite phase. The microhardness distributions on the three planes of NSSP-304 are more uniform than those of CPSS-304. The microhardness value of NSSP-304 on the rolling plane is about 40 HV larger than those on its other two planes, which is related to its weak texture ({110}<211>). Despite the weak texture of NSSP-304, the corrosion rates of NSSP-304 vary with corrosion time within the narrower ranges than those of CPSS-304 during potentiostatic polarization in 0.5 mol/L HCl solution at room temperature and in 6%FeCl3 (mass fraction, %) solution (35℃). The corrosion rates of NSSP-304 are smaller than those of CPSS-304 in the two kinds of solutions. The pitting corrosion resistances of NSSP-304 are larger than those of CPSS-304 in the two kinds of aqueous solutions. These results demonstrate that the texture, the high microhardness, the twins and high-density dislocation of NSSSP-304 did not degrade its uniform and pitting corrosion resistances even though NSSP-304 suffered from severe deformation during its production process (the total deformation larger than 70%). Compared to CPSS-304, the higher microhardness, the improved uniform and pitting corrosion resistances of NSSP-304 are attributed to its different valence electron configurations (the larger binding energies of valence electrons, the larger weights of valence electrons at higher energy levels, the smaller weights of valence electrons at lower levels and the larger work function) owing to its grain refinement, dislocation accumulation, deformation twins and larger fraction of LAGBs grains.