(福州大學(xué) 材料科學(xué)與工程學(xué)院， 福州 350002)
摘 要: 在應(yīng)變速率為5.56×10-5~5.56×10-3 s-1的范圍內(nèi)，從223~773 K， 每間隔25 K的溫度下對(duì)易拉罐用鋁材進(jìn)行系列拉伸實(shí)驗(yàn)， 探索其鋸齒屈服規(guī)律。 結(jié)果表明： 易拉罐用鋁材在形變過(guò)程中會(huì)出現(xiàn)動(dòng)態(tài)應(yīng)變時(shí)效現(xiàn)象； 在給定的應(yīng)變速率下， 動(dòng)態(tài)應(yīng)變時(shí)效僅發(fā)生在一定的溫區(qū)； 在該溫區(qū)內(nèi)， 應(yīng)變速率敏感性出現(xiàn)了負(fù)值， 強(qiáng)度出現(xiàn)了一個(gè)平臺(tái)； 并存在臨界應(yīng)變量轉(zhuǎn)折溫度Tt， 在溫度低于Tt 的溫區(qū)， 動(dòng)態(tài)應(yīng)變時(shí)效是由于Mg溶質(zhì)原子氣團(tuán)與位錯(cuò)交互作用的結(jié)果； 在溫度高于Tt 的溫區(qū)， 存在兩個(gè)相反的熱激活過(guò)程， 一是溶質(zhì)原子運(yùn)動(dòng)至位錯(cuò)并釘扎位錯(cuò)； 另一個(gè)過(guò)程是吸收源吸收溶質(zhì)原子減弱對(duì)位錯(cuò)的釘扎作用。
關(guān)鍵字: 鋁合金；鋸齒屈服；動(dòng)態(tài)應(yīng)變時(shí)效；Portevin-Le Chatelier效應(yīng)
（ College of Materials Science and Engineering, Fuzhou University,
Fuzhou 350002, China）
Abstract: An aluminum alloy used for can body stock was subjected to tension test at a strain rates range of 5.56×10-5 to 5.56×10-3 s-1 and temperature between 223 to 773 K to investigate the effects of temperature and strain rate on its mechanical properties. The serration flow phenomenon is associated with dynamic strain aging (DSA) and yield a negative strain-rate dependence of the flow stress. In the serrated yielding temperature region a critical transition temperature (Tt) exists. The critical plastic strain for the onset of serrations has a negative or positive temperature coefficient within the temperature region lower or higher than Tt. According to the activation energy, it is believed that the process at the temperature region lower than Tt is caused by the interaction between Mg solute atom atmosphere and dislocation. In the positive coefficient region two reverse thermal activation processes occur simultaneously. One is the solute atoms diffuse to the moving dislocation and pin the dislocation. The other one is the absorbed resource absorbs the solute and diminishes the pinning effect.
Key words: aluminum alloy; serration flow; dynamic strain aging; Portevin-Le Chatelier effect
