焊后時效處理對2219鋁合金VPTIG接頭微區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,焊接接頭各微區顯微組織和硬度發生的變化不同。熱影響區中的完全回復區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;焊縫區變化相對較小,其顯微硬度的最高漲幅出現在210℃,且小于前者;熱影響區中的過時效區最為穩定,顯微硬度的最大增長同樣出現在160℃,但漲幅很小。透射電鏡觀察表明,焊接接頭各微區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.