固溶温度和稳定化工艺对GH864合金疲劳裂纹扩展特征的影响

研究了不同固溶温度和稳定化处理工艺后GH864合金的裂纹扩展情况.通过分析合金的微观组织,断口形貌以及lga-lgN_i/N_f、da/dN-a及da/dN-N曲线特征,定量计算了裂纹萌生期、稳态扩展期及失稳瞬断期在整个疲劳断裂过程中所占比例,并进一步分析影响各自比例的微观组织因素.结果表明:随着固溶温度的升高,晶粒尺寸增加,合金的裂纹扩展速率降低,同时裂纹的萌生期的比例降低,而裂纹的扩展期比例则会增加;随稳定化时间的延长和温度的升高,晶界碳化物析出量增加,降低了合金的裂纹扩展速率,但是裂纹萌生期的比例在逐渐增加.

Influence of solution temperature and stabilization treatment on the fatigue crack growth feature of GH864 alloy

The crack propagation of GH864 alloy with different solution temperatures and stabilization treatments was studied.The percentages of crack initiation period,propagation period and final fracture period in the whole fatigue failure process were calculated by analyzing the microstructure,fracture morphology and lga-lgN_i/N_f,da/dN-a and da/dN-N curves.The influence of microstructural factors on the percentages of each period was analyzed.The result shows that with increasing solution temperature,the grain size of GH864 alloy enlarges,the crack growth rate decreases,meanwhile the percentage of crack initiation period decreases but the percentage of crack propagation period increases.With the time prolonging and the temperature rising in the stabilization process,the amount of carbides precipitated at grain boundaries increases,thereby the crack propagation rate decreases,but the percentage of crack initiation period is gradually increasing.