cr1mo钢中磷的平衡及应力引起的非平衡晶界偏聚word格式论文.docx

后，在520℃无应力时效1000h使晶界浓度达到热力学平衡，然后在40、200 和350MPa拉应力下分别时效不同的时间，用俄歇电子能谱仪测量P晶界浓 度，得到 P偏聚动力学。 40MPa拉应力引起的偏聚动力学有一个偏聚峰； 350MPa拉应力引起的偏聚动力学有两个偏聚峰；200MPa拉应力引起的偏聚 动力学有两个偏聚峰和一个贫化谷。同时测量了这些条件下的蠕变曲线， 40MPa拉应力下几乎不发生蠕变，200和350MPa拉应力下发生了蠕变，且350MPa拉应力下的蠕变更加明显。综合分析后认为在应力时效过程中，弹 性变形和蠕变变形共同影响P的偏聚动力学。通过考虑空位流和复合体流，建立了一个低应力引起的非平衡晶界偏聚 动力学模型。利用该模型，可以预测不同条件(应力、温度、晶粒尺寸、空 位迁移能和复合体的迁移能等)下的偏聚动力学。模拟了 40 MPa拉应力下的 P偏聚动力学，结果与实验符合良好。本工作的完成促进了晶界偏聚和晶界脆化现象的认识，进一步完善了晶 界偏聚理论，对工程实践具有重要的指导意义。关键词 晶界偏聚；脆化；应力；模型；韧-脆转变温度AbstractSolute (impurity or alloying elements) segregation at grain boundaries has an important effect on the mechanical behavior of engineering materials. It has been an interesting topic to metallurgists and material engineers. Solute segregation at grain boundaries may be clarified into equilibrium segregation and non-equilibrium segregation. Studies of equilibrium grain boundary segregation have started long before, and its theory has approached almost perfect. However, there are many things unknown about the non-equilibrium grain boundary segregation, especially the stress-induced non-equilibrium segregation. The segregation behaviors studied before were mainly in a non-stress state. However, the materials in service are usually subject to an applied stress, and thus the research into stress-induced non-equilibrium grain boundary segregation is more important in engineering practice.Due to their excellent high-temperature mechanical properties, Cr-Mo low alloy structural steels are widely used in the power and petrochemical industries. Nevertheless, when the materials serve in a high temperature and pressure environment, impurities, such as phosphorus, sulfur, tin and antimony, would segregate to the grain boundary, making it embrittled. The fracture toughness of the materials is lowered, and the ductile-to-brittle transition temperature (DBTT) is increased. Grain boundary embrittlement deteriorates the service performance, making the materials fracture intergranularly, which may c