喷射成形7055铝合金淬火残余应力分析

Analysis of Quenching Residual Stress of Spray-forming 7055 Aluminum Alloy

喷射成形7055铝合金基座本体在淬火以及后续加工过程中发生了开裂失效,通过对失效件结构的宏观观察、失效断口的微观观察、能谱成分分析和金相分析等针对性检查以及人工打断断口的对比分析,确定此次7055铝合金基座本体的失效模式是在淬火应力作用下发生的过载断裂,断裂可能与热处理冷却速度过快引起的淬火应力过大有关。对淬火冷却介质温度进行调整,7055铝合金经470℃的固溶处理2 h后,分别采用50、60和70℃的温水淬火,然后进行了多次残余应力检测。检测结果表明,在淬火工艺常用的淬火介质温度范围内,随着淬火冷却介质温度的升高,淬火残余应力下降,铝合金结构体的开裂风险减小,推荐采用70℃的温水淬火处理以降低7055铝合金的淬火应力。

Spray-forming 7055 aluminum support took place cracking failure during quench and subsequent machining.Marco inspection of the fracture structure and micro inspection of the fracture surface,energy spectrum analysis and metallographic examination were carried out,furthermore,contrastive analysis of man-made fracture surface was also carried out.The results showed that the failure mode was 7055 aluminum alloy support showed overload fracture by the effect of the quench stress,the fracture was related to excessive quenching stress which was caused by the faster cooling rate.The quench cooling medium temperature was adjusted,after 470℃two hours solution treatment,7055 aluminum alloy was quenched in boiling water(50,60 and 70℃separately),then residual stress was repeatedly tested.The test results showed that the residual stress decreased with the increasing of the cooling medium temperature in the usual medium temperature range of quench,and the risk of aluminum alloy structural cracking was reduced,quenching in boiling water of 70℃was recommended to decrease the residual stress of 7055 aluminum alloy.