电解加钛改进活塞合金ZL108的疲劳裂纹扩展性能

Improving Fatigue Crack Growth Property of Piston Alloy ZL108 by Electrolyzed Titanium

采用对比试验方法,研究加钛和加钛方式对活塞合金ZL108疲劳裂纹扩展性能的影响。分别以电解低钛铝基合金和Al-5.3%Ti中间合金为基,熔配与ZL108合金成分基本相同的两种加钛的ZL108合金,分别记为ZL108D和ZL108R,测试三种合金的疲劳裂纹扩展速率da/dN和门槛值ΔKth。运用数据代表点拟合的新方法处理同组试样的疲劳裂纹扩展试验数据,结果表明:相对ZL108合金而言,ZL108D和ZL108R合金具有更高的抗疲劳裂纹扩展能力。两种加钛合金抗疲劳裂纹扩展性能有所提高的主要原因在于钛的细化作用,使α(Al)晶粒二次枝晶间距变小,硅颗粒分布更加均匀,圆形度提高且平均直径变小,微观上增加了疲劳裂纹扩展的阻力。而两种加钛方式的影响则差别不大。

The effects of different additions of titanium on fatigue crack growth property of piston alloy ZL108 were studied respectively. ZL108D and ZL108R cast alloys are respectively made with the electrolyzed aluminum - titanium alloy and Al - 5.3% Ti master alloy, and the compositions of these two alloys accord with that of ZL108 alloy except the additions of titanium. One new data processing method with representative data points was used in the simulation of the parameters of fatigue crack growth rate da/dN. It was shown that addition of titanium into ZL108 can improve the resistance to fatigue crack growth the refinement of which can decrease of the second dendrite spacing of α（Al） and increases of evenness and roundness of eutectic