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研究了σ相对核电一回路主管道Z3CN20.09M不锈钢冲击韧性的影响,利用原位拉伸、显微硬度、断口形貌等手段分析了σ相的脆化机理.结果表明,σ相显著降低一回路主管道不锈钢的冲击韧性,时效处理Z3CN20.09M不锈钢中以σ相为主的由铁素体共析分解生成的(σ+γ2)结构的硬度远高于奥氏体基体,两者变形协调性差,(σ +γ2)结构阻碍位错滑移,提高材料强度,同时降低塑性;(σ+γ2)结构内部存在大量高能量σ/γ2和a/σ/γ2非共格界面,变形时应力在此处集中,成为潜在裂纹源,易萌生裂纹.高应变速率下,裂纹迅速在其内部产生、扩展是材料韧性降低、变脆的本质原因.
The influence of σ on the impact toughness of Z3CN20.09M stainless steel was studied, and the embrittlement mechanism of σ phase was analyzed by means of in-situ tensile test, microhardness and fracture morphology. The results showed that the σ phase decreased significantly Impact toughness and aging treatment of stainless steel in the main pipe of the circuit The hardness of the (σ + γ2) structure formed by ferrite eutectoid decomposition in the Z3CN20.09M stainless steel is much higher than that of the austenite matrix, and the deformation coordination (Σ + γ2) structure impedes the slip dislocation and enhances the material strength and reduces the plasticity. (Σ + γ2) structure has a large number of non-coherent interfaces with high energy σ / γ2 and a / σ / γ2. Here concentrated to become a potential source of cracks, easy to crack.High strain rate, the rapid generation of cracks in its internal expansion is the material to reduce the toughness, brittle nature of the reasons.