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采用真空感应炉熔炼不同镍铬当量比的超超临界转子用钢锭,分析镍铬当量比对δ-铁素体析出的影响。研究表明:标准成分范围内铸锭中析出的δ-铁素体是由于冷却过程中非平衡相变引起的,高镍铬当量比的铸锭偏析较轻,δ-Fe呈小块状分布,通过再结晶和热挤压可以被完全吸收;低镍铬当量比的铸锭偏析加重,δ-铁素体含量明显增多,呈网状分布,热加工后呈链条状分布在晶界位置,很难将其完全消除;随镍铬当量比的提高,δ-铁素体含量减少,合金冲击韧性明显改善。
The effect of Ni-Cr equivalence ratio on the precipitation of δ-ferrite was analyzed by using a vacuum induction furnace to smelt ingots of ultra-supercritical rotor with different Ni-Cr equivalence ratios. The results show that the δ-ferrite precipitated in the ingot in the standard composition is due to the non-equilibrium phase transition during the cooling process. The ingot segregation with high nickel-chromium equivalent ratio is lighter and the δ-Fe is in the form of small block. By recrystallization and hot extrusion can be completely absorbed; low nickel-chromium equivalent ratio of ingot segregation aggravated, δ-ferrite content increased significantly, reticular distribution, the thermal processing was chain-like distribution in the grain boundary position, it is It is difficult to completely eliminate; with the increase of nickel-chromium equivalent ratio, δ-ferrite decreased, the impact toughness of the alloy improved significantly.