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利用OM,EPMA,SEM,EDS,TEM等研究了固溶温度对S32760双相不锈钢热轧板显微组织的影响及合金元素的分布特征,并通过电化学工作站测定了材料的耐点蚀性能.结果表明,S32760双相不锈钢在1080℃以上高温固溶过程中,N元素从g相扩散转移至d相中.若固溶后缓慢冷却,则N原子又重新迁移回g相中;如果固溶后水冷,则N原子来不及扩散,于d相中原位弥散析出Cr2N颗粒.Cr2N颗粒的数量由淬火前的固溶温度决定,温度越高数量越多.当固溶温度从1100℃升至1300℃时,d相中N的固溶度快速上升,其显微硬度由281 HV提高至345 HV;而g相由于相比例降低也使得N的浓度间接上升,显微硬度由290 HV升至314 HV.同时,由于实验钢中含有W,S32760双相不锈钢热轧板在1040℃以下热处理有s相析出,因此其固溶水冷温度区间较窄,最佳固溶温度为1060℃.此温度保温60 min后水冷,试样中无析出物,Brinell硬度为249 HBW,点蚀电位为1068 m V,维钝电流密度为1.48×10-4A/cm2.
The effect of solution temperature on the microstructure of hot-rolled S32760 stainless steel and the distribution characteristics of alloying elements were investigated by OM, EPMA, SEM, EDS and TEM. The pitting corrosion resistance of the material was measured by electrochemical workstation. The results show that during the solid solution process of S32760 duplex stainless steel at high temperature above 1080 ℃, the N element diffuses and diffuses from the g phase to the d phase, and if the solid solution cools slowly, the N atoms migrate back into the g phase. If the solid solution After cooling, the N atom is too late to diffuse, and the Cr2N particles are precipitated in situ in the d phase.The amount of Cr2N particles is determined by the solution temperature before quenching, and the higher the temperature, the more the number increases, and when the solution temperature increases from 1100 ° C to 1300 ° C , The solid solubility of N rapidly increases in phase d, and its microhardness increases from 281 HV to 345 HV. However, due to the phase decrease of phase g, the concentration of N indirectly increases and the microhardness increases from 290 HV to 314 HV At the same time, since the experimental steel containing W, S32760 duplex stainless steel hot-rolled plate below 1040 ℃ s phase precipitation, so its solution water cooling temperature range is narrow, the optimal solution temperature is 1060 ° C. This temperature 60 min after water cooling, no precipitate in the sample, Brinell hardness of 249 HBW, pitting potential 1068 m V, passive current density was 1.48 × 10-4A / cm2.