摘要
对GH4975合金铸锭铸态凝固组织进行了分析,对热处理过程中偏析元素扩散与析出相回溶规律进行了系统研究.结果表明:在1180～1220℃、均匀化2～20 h的过程中,延长保温时间和提高加热温度均可以有效改善W、Nb、Ti、Al等偏析元素的均匀化程度,同时提高γ'强化相及(γ+γ')共晶相的回溶程度,但MC碳化物无法通过高温均匀化处理有效回溶.同时计算可得,(γ+γ')相的激活能Q为342.552 kJ∕mol,W、Nb、Ti、Al元素的扩散常数D0分别为5.85×10-7、9.80×10-6、2.71×10-5、5.35×10-5 m2∕s,扩散激活能Q的值分别为245.749、271.634、281.651、298.882 kJ∕mol.
Abstract
This article analyzes the as-cast solidification structure of GH4975 alloy ingots and systematically studies the diffusion of segregated elements and the redissolution rules of precipitated phases during heat treatment.The results show that during the homogenization process at 1180～1220℃ for 2～20 h,extending the holding time and increasing the heating temperature can effectively improve the homogenization degree of segregated elements such as W,Nb,Ti,Al,and increase the redissolution degree of the strengthening phase of y' and ( y+y') eutectic phase.However,MC carbides cannot be effectively redissolved through high-temperature homogenization treatment.At the same time,it can be calculated that the activation energy Q of the ( y+y') phase is 342.552 kJ/mol,and the diffusion constants D0 of W,Nb,Ti,and Al elements are 5.85 × 10-7,9.80 × 10-6,2.71 × 10-5,and 5.35 × 10-5 m2/s,respectively.The values of diffusion activation energy Q are 245.749,271.634,281.651,and 298.882 kJ/mol,respectively.
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