Microsegregation and homogenization of nickel base corrosion resistant alloy C-276 ingots
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摘要: 利用光鏡、掃描電鏡和能譜儀等顯微組織分析方法研究了鎳基耐蝕合金C-276經真空冶煉+電渣重溶后鑄錠的枝晶特點和元素偏析情況,根據殘余偏析指數模型計算結果選取了四種均勻化實驗制度,并通過均勻化實驗后的組織分析和Gleeble1500試驗機熱模擬鍛造實驗驗證,最終確立了適合C-276合金的均勻化工藝.結果表明:合金中偏析程度最嚴重的元素為Mo;在選取的四種均勻化制度中,采用1170℃下加熱20h的處理方式不僅可以較好地實現成分均勻化,還能保證晶粒尺寸不過度長大,從而確保合金的熱加工塑性,是最為合理的均勻化制度.實驗也證明利用殘余偏析指數模型,計算結果與實驗結果基本吻合,在預測和評價C-276合金均勻化工藝上是可信的.Abstract: The microstructure and microsegregation of nickel base corrosion resistant alloy C-276 vacuum-induction-melting and electroslag-remelting ingots were studied by optical microscope, scanning electron microscopy and energy dispersive X-ray spectroscopy. Based on the calculated results of the residual segregation parameter model, four homogenizing treatments were tested. Microstructure analysis and thermal compression test with a Gleeble 1500 machine were used to verify the effect of homogenizing treatment. The results show that the severest segregated elements in C-276 is Mo, and 1170℃/20h is the most appropriate treatment for C-276 alloy in the study as it ensures homogenizing effect and reasonable grain size for optimizing the hot-working plasticity of the alloy. It is also proved that homogenization process of C-276 alloy can be effectively predicted and evaluated by the residual segregation parameter model, which basically agrees with the experimental results.
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Key words:
- nickel base alloys /
- corrosion resistant /
- microstructure /
- segregation /
- homogenization
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