摘要
针对不同P元素含量的GH4738合金,结合光学金相、扫描电镜形貌、TEM、EBSD分析,研究了P含量对GH4738合金持久性能的影响机理,探究了对合金性能有利的P元素含量范围。结果表明:合金的持久性能随着P含量的升高,呈先增大后减小的趋势,P元素的最佳添加量在0.0040wt%至0.0091wt%之间,此时断裂形式为混合断裂。继续增加P元素,持久寿命降低30%~50%,持久塑性降低20%~70%,断裂形式变为脆性沿晶断裂。原因在于:P元素为晶界偏析元素,含量较低时,可通过在晶界占据空位缺陷降低晶界自由能,从而提高晶界碳化物形核率,而晶界上均匀弥散分布的M_(23)C_(6)型碳化物可抑制裂纹扩展,提高晶界强度,从而提高合金持久性能;P元素含量较高时,更倾向固溶于MC型碳化物,因此随着P含量进一步的提高,晶界上MC型碳化物数量增多而M_(23)C_(6)型碳化物相对减少,块状的MC型碳化物在晶界不均匀分布,从而导致试验合金持久性能不断降低。
The influencing mechanisms of P content on the creep rupture properties of GH4738 alloy and the optimum additive range of P element in this alloy were investigated by OM,SEM,TEM,and EBSD microscopic analyses.The results show that the creep rupture strength of the alloys shows a tendency of firstly increasing and then decreasing with the increase in P content.The optimal addition amount of P ranges from 0.0040wt%to 0.0091wt%,and the fracture morphology shows a mixed fracture type.With continuously increasing the P element,the endurance life is decreased by 30%–50%,the persistent plasticity is decreased by 20%–70%,and the fracture mode changes to brittle intergranular fracture.The main reasons are as follows.P,as a type of grain boundary segregation element,when its content is smaller,the segregated P element occupies the vacancy at the grain boundary to decease the free energy of grain boundary,thereby increasing the nucleation rate of carbides.Meanwhile,the uniformly dispersed M_(23)C_(6)-type carbides along grain boundaries can inhibit crack propagation and improve grain boundary strength,ultimately enhancing the creep resistance of the alloys.When P content is greater than the critical value,it has a tendency to solute into MC-type carbides.Consequently,with further increase in P content,the amount of MC-type carbides at grain boundaries is increased while M_(23)C_(6)-type carbides are decreased relatively.The blocky MC-type carbides become unevenly distributed along grain boundaries,leading to a continuous degradation in the creep resistance of the experimental alloys.
作者
荣义
侯为学
王磊
曲敬龙
杜金辉
Rong Yi;Hou Weixue;Wang Lei;Qu Jinglong;Du Jinhui(Central Iron and Steel Research Institute Co.,Ltd,Beijing 100081,China;Gaona Areo Materials Co.,Ltd,Beijing 100081,China)
出处
《稀有金属材料与工程》
北大核心
2025年第8期2094-2103,共10页
Rare Metal Materials and Engineering
基金
科技部重大专项(2021YFB3700403)。
