吕穿江, 张乐, 陈旋, 吴晓春. 球化组织对AISI 420型钢淬回火特性及耐蚀性能的影响[J]. 工程科学学报, 2019, 41(9): 1142-1151. DOI: 10.13374/j.issn2095-9389.2019.09.005
引用本文: 吕穿江, 张乐, 陈旋, 吴晓春. 球化组织对AISI 420型钢淬回火特性及耐蚀性能的影响[J]. 工程科学学报, 2019, 41(9): 1142-1151. DOI: 10.13374/j.issn2095-9389.2019.09.005
LÜ Chuan-jiang, ZHANG Le, CHEN Xuan, WU Xiao-chun. Effect of spheroidized microstructure on quenching and tempering characteristics and corrosion resistance of AISI 420-type steel[J]. Chinese Journal of Engineering, 2019, 41(9): 1142-1151. DOI: 10.13374/j.issn2095-9389.2019.09.005
Citation: LÜ Chuan-jiang, ZHANG Le, CHEN Xuan, WU Xiao-chun. Effect of spheroidized microstructure on quenching and tempering characteristics and corrosion resistance of AISI 420-type steel[J]. Chinese Journal of Engineering, 2019, 41(9): 1142-1151. DOI: 10.13374/j.issn2095-9389.2019.09.005

球化组织对AISI 420型钢淬回火特性及耐蚀性能的影响

Effect of spheroidized microstructure on quenching and tempering characteristics and corrosion resistance of AISI 420-type steel

  • 摘要: 对比研究了两种AISI 420型钢球化组织的平均粒径和圆整度,并对两种钢材进行了不同淬火和回火处理工艺.然后通过硬度测试、扫描电子显微镜(SEM)和X射线衍射仪(XRD)来比较球化组织对淬回火特性的影响,同时借助动电位极化曲线测试和质量分数3.5% NaCl溶液浸泡腐蚀来分析耐蚀性能的差异.结果表明:细小弥散的球化组织在淬火时可以提高AISI 420型钢的C元素的固溶量,提高了其淬硬性,但是会提高残留奥氏体的含量;尺寸更小的退火态碳化物可以使AISI 420型钢的基体在奥氏体化过程中溶解更多的Cr元素,从而使得其在淬回火后基体Cr含量更高,减小贫Cr区产生几率,最终显示出更好的点蚀抗力;更少的大尺寸的未溶碳化物在腐蚀环境中降低了点蚀形核几率,提高了AISI 420型钢的耐蚀性能.所以在250℃回火时,AISI 420型钢耐蚀性好且硬度高,在480℃回火后,耐蚀性最差.

     

    Abstract: Owing to the increasing surface quality of plastic products, such as plastic medical supplies and resin lenses, the demands of plastic molds have increased. Corrosion and wear are the most important failure behaviors of plastic molds; therefore, best-quality plastic mold materials should feature high hardness and corrosion resistance. Super martensitic stainless steels show the optimum combination of strength, hardness, and wear and corrosion resistance after appropriate heat treatment. Therefore, they are the most mainstream materials in the field of high-grade die steel, especially AISI 420. Herein, AISI 420 steels with different average particle sizes and roundness of spheroidized microstructures were treated by different quenching and tempering procedures. Hardness test, scanning electron microscope, and X-ray powder diffraction were then used to research the impact of the spheroidized microstructure on the quenching and tempering characteristics. Additionally, the differences in corrosion resistance were investigated using a potentiodynamic polarization test and soaking corrosion in 3.5% NaCl solution. The results show that small and diffuse spheroidized microstructures increase the solution degree of the C element in AISI 420 steel during quenching, improving the hardening capacity, but increasing the amount of retained austenite simultaneously. Smaller-sized Cr-rich carbides enable the AISI 420 steel to dissolve more Cr element in the austenitizing procedure; therefore, the Cr content of the matrix is higher after quenching and tempering, which reduces the probability of the chromium-depleted area and shows better pitting resistance. Fewer large-sized, undissolved carbides reduce the probability of pitting nucleation in a corrosive environment and improve the corrosion resistance of AISI 420 steel. After tempering at 250℃, AISI 420 shows excellent corrosion resistance and higher hardness. While the steel exhibits the highest hardness, it also bring about the greatest damage to corrosion resistance when tempered at 480℃.

     

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