(1. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410083;
2. 中南大學(xué) 教育部有色金屬材料科學(xué)與工程重點(diǎn)實(shí)驗(yàn)室，長沙 410083;
3. 湖南工學(xué)院 機(jī)械工程系，衡陽 421002)
摘 要: 研究高低溫循環(huán)熱處理對EW94合金擠壓−T6態(tài)板材組織與力學(xué)性能的影響。結(jié)果表明：在(−196 ℃, 12 h)+(RT, 12 h)制度下，循環(huán)熱處理對合金的力學(xué)性能無明顯影響；經(jīng)(−196 ℃, 12 h)+(≤200 ℃, 12 h)循環(huán)熱處理N(N≤15)次后，樣品抗拉強(qiáng)度有所提高；經(jīng)(−196 ℃, 12 h)+(200 ℃, 12 h)循環(huán)4次后，樣品抗拉強(qiáng)度達(dá)到峰值，為413 MPa；經(jīng)(−196 ℃, 12 h)+(250 ℃, 12 h)循環(huán)處理后，樣品抗拉強(qiáng)度略有下降，伸長率略有提高；而經(jīng)(−196 ℃, 12 h)+(300 ℃, 12 h)循環(huán)處理后，樣品抗拉強(qiáng)度,急劇下降至307 MPa，但伸長率由2.8%提高到5.6%；隨循環(huán)次數(shù)的增加，合金力學(xué)性能基本保持穩(wěn)定。合金在高低溫循環(huán)過程中的相變是影響其力學(xué)性能的主要因素。
關(guān)鍵字: 高低溫循環(huán)；時(shí)效；析出相；斷裂；伸長率
mechanical properties of EW94 magnesium alloy
ZHAO Feng-jin1, 2, XU Li1, 2,
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education, Central South University, Changsha 410083, China;
3. Department of Mechanical Engineering, Hunan Institute of Technology, Hengyang 421002, China）
Abstract:The effects of high-low temperature cycle on microstructures and mechanical properties of EW94 alloy with extruded-T6 temper were investigated. The results indicate that there is no effect on the mechanical properties when the aged alloy is held at −196 ℃ and ambient temperature. There is some increment in ultimate strength of the alloy when it is treated by (−196 ℃, 12 h)+(≤200 ℃, 12 h) regime for N(N≤15) times, the maximum ultimate strength of 413 MPa is derived when the alloy was treated by (−196 ℃, 12 h)+(200 ℃, 12 h) for 4 times. There was some decrease in ultimate strength but some increment in elongation when treated by (−196 ℃, 12 h)+(250 ℃, 12 h). However, the ultimate strength abruptly decreases to 307 MPa and the elongation increases to 5.6% when the samples are treated by (−196 ℃, 12 h)+(300 ℃, 12 h), and the mechanical properties are stable at this level as the number of cycles increases. The phase transformation during the heat-treatment at alternate temperature is the key factor of the variation in mechanical properties.
Key words: high-low temperature cycle; ageing; precipitation; fracture; elongation
