(上海交通大學(xué) 材料科學(xué)與工程學(xué)院，上海 200240)
摘 要: 為了研究鎳基合金焊材FM-52M的高溫失延裂紋(DDC)，采用改進(jìn)的應(yīng)變-裂紋(STF)實(shí)驗(yàn)方法，提出新的裂紋敏感性判據(jù)——晶界滑移量。并將之與裂紋數(shù)量相結(jié)合定量評(píng)估不同溫度、不同變形量條件下材料的DDC敏感性。結(jié)果表明：本研究中所得到的材料臨界變形量6%大于傳統(tǒng)STF方法得到的4%的臨界變形量。預(yù)熱處理、峰值溫度、變形速率等條件都能顯著影響DDC的敏感性。此外，利用顯微硬度標(biāo)記了許多微區(qū)，并對(duì)實(shí)驗(yàn)前后的微區(qū)進(jìn)行了SEM觀(guān)察，探討晶界滑移與析出物在DDC的萌生與擴(kuò)展過(guò)程中的作用。
關(guān)鍵字: 晶界滑移；高溫失延裂紋；鎳基合金
（School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China）
Abstract:According to the improved strain-to-fracture test (STF) method, the value of grain boundary sliding was used as a new criterion to evaluate the susceptibility of ductility-dip cracking (DDC) in Ni-based alloy filler metal 52M(FM-52M) under various temperature and deformation conditions. The results show that the threshold strain of the test is 6%, which is larger than 4% obtained by previous STF method. Heat pretreatment, peak temperature, strain rate all have a great influence on the DDC susceptibility. Microhardness was used to mark interested micro-regions, from which SEM images were made before and after the test in order to explain the roles of grain boundary sliding and precipitates in DDC.
Key words: grain boundary sliding; ductility-dip cracking; Ni-based alloy
