孕育与变质处理对高Ni-Cr铸铁的影响

研究了75SiFe孕育和REMg变质对金属型铸造高Ni-Cr铸铁铸态和回火态的组织与硬度的影响。结果表明,75SiFe孕育处理使石墨析出数量增多,增加了奥氏体+石墨的共晶体数量,石墨片长度增加,而板条状碳化物数量减少。REMg变质促进点球状石墨析出,石墨析出数量减少,碳化物转变为断网分布,即呈岛状和骨骼状,高冷却速度弱化REMg的变质作用。75SiFe孕育回火处理促进奥氏体分解,回火后残余奥氏体较多。75SiFe孕育降低高Ni-Cr铸铁的铸态和回火态硬度,而REMg变质可略提高高Ni-Cr铸铁的铸态和回火态硬度。

Effects of Inoculation and Modification on High Ni-Cr Cast Iron

The effects of 75SiFe inoculation and REMg modification on the as-cast and as-tempered microstructure and hardness of the high Ni-Cr cast iron cast in metal mold were investigated.The results showed：75SiFe inoculation caused increased amount of graphite separating,increased count of austenite ＋ graphite eutectic,lengthening of graphite flake,and decreased amount of the plate-strip shaped carbide.REMg modification promoted the dot-spheroidal graphite separating,reduced count of graphite separating,the carbide distribution changed into intermittent net type distribution,i.e.distribution as island and skeleton.High speed cooling reduced the modification effect of the REMg.75SiFe inoculation decreased the as-cast and as-tempered hardness of the high Ni-Cr cast rion.