焊后時效處理對2219鋁合金VPTIG接頭微區(qū)組織和顯微硬度的影響Effects of Aging Treatments on Microstructure and Micro-hardness of 2219-T87 Welds

研究了不同溫度焊后時效處理對2219鋁合金變極性鎢極氬弧焊(VPTIG)接頭各微區(qū)顯微組織的影響,采用顯微硬度測試和透射電鏡觀察分析焊接接頭各微區(qū)析出相的形貌和分布。結果表明,焊后時效處理溫度不同,焊接接頭各微區(qū)顯微組織和硬度發(fā)生的變化不同。熱影響區(qū)中的完全回復區(qū)對焊后時效最為敏感,低溫處理時顯微硬度就有明顯增長,并在160℃處理時達到最大漲幅;焊縫區(qū)變化相對較小,其顯微硬度的最高漲幅出現(xiàn)在210℃,且小于前者;熱影響區(qū)中的過時效區(qū)最為穩(wěn)定,顯微硬度的最大增長同樣出現(xiàn)在160℃,但漲幅很小。透射電鏡觀察表明,焊接接頭各微區(qū)的顯微硬度變化主要與時效強化相的析出行為有關。

The effects of post-weld aging treatment on microstructure and micro-hardness of aluminum alloy grade 2219 welds are presented. The microstructure including the precipitates distribution and morphology was observed by transmission electron microscopy (TEM) and micro-hardness was measured to characterize the different micro-areas across the weld. The results show that different post-weld aging temperatures lead to variations in microstructure and micro-hardness across the weld. Full reversion area (RA) in the heat affected zone (HAZ)is the most sensitive to the aging process. Micro-hardness in this area shows obvious improvement when it is processed at low aging temperatures, and the maximum increase is achieved at 160℃. The micro-hardness in the weld metal (WM) remains relatively stable. The maximum increase is achieved at 210℃. The over-aged area (OA) shows a very limited increase in micro-hardness and the maximum value is obtained at 160℃. TEM observation revealed that the changes in micro-hardness of micro-areas across the weld are mainly related with the precipitate evolution during the aging process.