增进核电焊材用钢508Ⅲ洁净度的工艺实践

Process Practice of Improving Cleanliness of Steel 508Ⅲ for Nuclear Power Welding

核电焊材用钢508Ⅲ(/%:0.09~0.12C,0.30~0.40Si,1.45~1.65Mn,≤0.008P,≤0.008S,0.45~0.60Mo,0.60~0.75Ni)的生产工艺流程为20 t EAF-LF-VD-4 t铸锭-锻造150 mm×150 mm坯-轧制Φ5.5 mm盘条。采用精选炉料,以及高碱度渣、高FeO含量,钢水温度1 550~1 570℃等措施控制,电弧炉终点[P]≤0.002%,并选用低磷合金,使钢中磷含量≤0.006%;LF采用硅钙合金沉淀脱氧,SiC粉扩散脱氧、CaO-Al_2O_3-SiO_2渣系,碱度5.0~5.5,VD真空度≤67 Pa,Ar流量30~50 L/min,保护浇铸等措施后,3炉钢的分析结果表明,钢中气体含量为1.3×10^(-6)~1.5×10^(-6)[H],10×10^(-6)~14×10^(-6)[O]和44×10^(-6)~58×10^(-6)[N],满足核电焊材用钢508Ⅲ洁净度的要求。

The production process flowsheet of steel 508Ⅲ for nuclear power welding （/% ： 0. 09 - 0. 12C, 0. 30 0. 40Si, 1.45 - 1.65Mn, ≤0. 008P, ≤0. 008S, 0. 45 -0. 60Mo, 0. 60 -0. 75Ni） is 20 t EAF-LF-VD-4 t ingot- forged to 150 mm × 150 mm billet-rolled to ≤5.5 mm coil. With process measures including using quality charge, high basicity slag and high FeO content, and controlling liquid temperature 1 550 -0 1 570 ℃, the EAF end [ P] is ≤0. 002%, and using low phosphorus alloys, the phosphorus content in steel is ≤0. 006% ; in LF refining process using silicon-calcium alloy for killing and SiC powder for diffusion deoxidation, and using CaO-Al2O3-SiO2 slag series with basicity 5.0 - 5.5, in VD process vacuum ≤ 67 Pa and Ar flow rate 30 - 50 L/min, and shielding casting etc measures the analysis results of 3 heats steel show that the gas content in steel is 1.3 ×10^-6 - 1.5×10^-6[H], 10 ×10^-6 - 14×10^-6[O] and 44 ×10^-6-58×10^-6[ N] to meet the cleanliness requirement of steel 508 llI for nuclear power wielding.