17-7PH沉淀硬化不锈钢电渣重熔过程洁净度的变化

采用35 t电弧炉-AOD脱碳-LF精炼-模铸工艺制备了17-7PH沉淀硬化不锈钢自耗电极，并通过气体保护电渣炉重熔得到了2 t重的电渣锭。利用ASPEX扫描电镜分析了电渣重熔前后17-7PH钢中夹杂物数量、尺寸、成分的变化规律，并采用SEM-EDS进一步观察夹杂物的形貌及组成。研究结果发现，电渣重熔后，O含量由6.6×10^-6降至5.7×10^-6,N含量由200×10^-6降至180×10^-6。重熔前后夹杂物的类型没有变化，重熔后总的夹杂物数量大幅减少，特别是大颗粒夹杂物的数量明显减少、尺寸减小。电渣锭中总的夹杂物以AlN夹杂物为主，其尺寸较大、数量最多。为了提高17-7PH钢电渣锭的洁净度，应尽可能减少自耗电极中的N含量，以减少电渣重熔过程AlN夹杂物的生成量。

Changes of Cleanliness during Electroslag Remelting of 17-7PH Precipitation Hardening Stainless Steel

17-7PH precipitation hardening stainless steel consumable electrode is prepared by 35 t electric arc furnace- AOD decarbonization- LF refining- ingot casting process, and 2 t electroslag ingot is obtained by gas shielded electroslag furnace. The change law of inclusion number, size and composition in 17-7PH steel before and after electroslag remelting are analyzed by ASPEX scanning electron microscope, and the morphology and type of inclusions in steel is further observed by SEM-EDS. The experimental results show that, after electroslag remelting, the oxygen content decreases from 6.6 x 10^-6 to 5.7 x 10^-6 and the nitrogen content decreases from 200 x 10^-6 to 180 x 10^-6. The types of inclusions don't change before and after remelting, but the total number of inclusions decreases significantly, especially the number and size of large particle inclusions decrease significantly. The total inclusions in electroslag ingot are mainly AIN inclusions, which are large in size and most in quantity. In order to improve the cleanliness of 17-7PH steel electroslag ingot , it is necessary to reduce the nitrogen content of consumable electrode as much as possible, so as to reduce the formation of AIN inclusions formed during electroslag remelting.