Abstract: The new process of EAF→VOD→LF+VD→ pouring 6 t electrode rod → vacuum consumable remelting （VAR） with lower smelting cost was adopted to produce 15-5PH stainless steel instead of the traditional VIM+VAR process， the causes of point defects were analyzed by scanning electron microscopy and ASPEX detection methods. The results show that calcium aluminate and aluminum spinite exist in the self-consuming electrode， the instability of vacuum consumable remelting process will draw the ingot crown and non-metallic float into the melting pool and remain in the consumable ingot， resulting in point defects after forging.Through process optimization and improvement， the VOD reduction slag is adjusted from 9 kg/t aluminum to 8 kg/t ferrosilicon and 5 kg/t aluminum， the composition of refining slag is adjusted from （mass fraction）CaO 50%-55%， SiO₂ 10%-15%， Al₂O₃ 20%-25% to CaO 45%-50%， SiO₂ 5%-10%， Al₂O₃ 33%-38%， vacuum consumable remelting speed is increased from 4.2 kg/min to 6 kg/min， and the melting drop time is increased from 0.23 s to 0.27 s， the cleanliness of consumable electrode has been greatly improved， the melting speed has been controlled steadily， the non-metal floating matter on the liquid surface of the molten pool has been removed， low and high magnification inspection of the finished material have met the standard requirements， and the inspection pass rate has been increased to more than 98%.

Key words: 15-5PH Stainless Steel, Point Defects, Refining Slag System, VAR, Droplet Time

摘要： 采用冶炼成本较低的EAF→VOD→LF+VD→浇注6 t电极棒→真空自耗重熔（VAR）的新工艺流程代替传统双真空冶炼工艺生产15-5PH不锈钢，使用扫描电镜、ASPEX等对其探伤点状缺陷进行检测，并分析其产生原因。结果表明，自耗电极中已存在铝酸钙及镁铝尖晶石非金属夹杂物，真空自耗重熔过程的不稳定，将锭冠和非金属漂浮物卷入熔池残留在自耗锭中，导致锻造成材后产生点状缺陷。通过工艺优化改进，VOD还原渣料由铝粒9 kg/t调整为硅铁8 kg/t、铝粒5 kg/t复合脱氧，精炼渣系成分由（质量分数）CaO为50％～55％、SiO₂为10％～15％、Al₂O₃为20％～25％调整为CaO为45％～50％、SiO₂为5％～10％、Al₂O₃为33％～38％，真空自耗重熔熔速由4.2 kg/min提高至6 kg/min、熔滴时间由0.23 s提高至0.27 s，自耗电极洁净度得到较大的提升，自耗重熔过程熔速控制稳定，熔池液面非金属漂浮物得以去除，成品材高低倍检验均满足标准要求，探伤合格率提高至98%以上。

关键词: 15-5PH不锈钢, 点状缺陷, 精炼渣系, 真空自耗重熔, 熔滴时间