一种高硅Cr-Ni不锈钢热处理后的显微组织转变

Temperature Time Dependent Microstructural Transformation in a High Silicon Containing Cr Ni Stainless Steel

研究了一种铸态σ相强化的高硅Ｃｒ－Ｎｉ不锈钢热处理后的显微组织转变。试验结果表明，在１１５０℃高温固溶状态下钢具有α＋γ双相组织；在固溶后冷却及８００℃附近时效过程中，α相和γ相不稳定，发生３种相变反应，即α→α＋σ、α→γ′＋σ及γ→γ＋σ。长期时效后，通过上述反应，最终形成以γ相为基体的γ＋σ双相组织。根据试验结果分析讨论了该钢的组织不稳定性、由α＋γ双相组织转变成γ＋σ组织的相变过程、σ相的形成及强化机制。

The temperature time dependent microstructural transformation in a high silicon containing Cr Ni stainless steel being capable of strengthening through the formation of σ phase was studied experimentally, in which the samples were machined from cast material of the steel and then heat treated by different regimes. The results showed that the alloy had α+γ duplex structure as solution annealing at high temperature 1 150 ℃. During cooling subsequent to solution annealing or ageing at about 800 ℃ there were three types of transformations occured in the alloy, i.e. α→α+σ, α→γ ′+σ and γ→γ+σ reactions. After long term ageing the alloy finally turned into γ+σ duplex microstructure with the γ phase as matrix. Based on the experimental results the structural instability of the alloy, the detail of the transformation of α+γ duplex structure to γ+σ microstructure, the formation of σ phase and the strengthening mechanism of the alloy were analysed and discussed.