(銅仁學(xué)院 物理與電子科學(xué)系，銅仁 554300)
摘 要: 研究不同加鈦方式和鈦含量對(duì)鑄造A356鋁合金常溫低周疲勞行為的影響，分析合金疲勞斷口的形貌特征。結(jié)果表明：4種A356合金均表現(xiàn)出明顯的循環(huán)硬化行為，但Ti含量(質(zhì)量分?jǐn)?shù))為0.14%的合金比Ti含量為0.10%的合金具有更高的循環(huán)硬化率。在低應(yīng)變時(shí)，加鈦方式對(duì)合金的循環(huán)硬化影響相近；而在高應(yīng)變時(shí)，電解加鈦A356合金表現(xiàn)為類似“飽和”的準(zhǔn)穩(wěn)定形變行為，熔配加鈦合金則表現(xiàn)為持續(xù)的循環(huán)硬化特征。加鈦方式對(duì)A356合金低周疲勞壽命的影響不明顯，其疲勞壽命僅受合金中Ti含量的影響；Ti含量為0.10%的A356合金較Ti含量為0.14%的合金具有更優(yōu)異的低周疲勞壽命，這主要是由于前者具有較低的屈服強(qiáng)度。
關(guān)鍵字: A356合金；低周疲勞；循環(huán)硬化；疲勞壽命
（Department of Physics and Electronics Science, Tongren University, Tongren 554300, China）
Abstract:Effects of the method of Ti-alloying and Ti contents on the low cycle fatigue (LCF) behavior of cast A356 alloys at room temperature were investigated, and the morphologies of fracture surfaces were analysed. The results show that four kinds of A356 alloys exhibit the evident cyclic hardening behavior, and the A356 alloys with 0.14%Ti(mass fraction) exhibit higher cyclic hardening rate than the alloys with 0.1%Ti. The cyclic hardening behavior influenced by method of Ti-alloying has similar trend when tested at low strain amplitude; while the A356 alloys by electrolysis (EA356) tested at high strain amplitude, reveal the quasi-stable deformation resembled “saturation” state, and for the A356 alloys by melting Al-10%Ti master alloys (MA356), the cyclic hardening continuously proceeds. There is no obvious difference between the LCF lives of A356 alloys fabricated by two methods of Ti-alloying, and the LCF life is only influenced by Ti contents in the alloys. The A356 alloy with 0.10 %Ti has a lower yield strength, which exhibits a longer LCF life than the alloys with 0.14%Ti.
Key words: A356 alloys; low cycle fatigue; cyclic hardening; fatigue life
