(中南大學(xué) 機(jī)電工程學(xué)院, 長沙 410083)
摘 要: 采用攪拌摩擦焊方法對厚度為25 mm的7A52鋁合金板進(jìn)行了單道焊實驗。結(jié)果表明： 在焊接25 mm板時, 工藝參數(shù)可調(diào)范圍較窄, 在旋轉(zhuǎn)速度為1500 r/min, 且焊接速度為40 mm/min時, 可以獲得較好的焊接性能, 抗拉強度可以達(dá)到330 MPa, 延伸率可以達(dá)到9.6%； 焊縫中存在3個組織變化區(qū), 其中焊核區(qū)內(nèi)是細(xì)小均勻的等軸晶, 平均晶粒大小在4 μm左右；焊縫兩側(cè)熱機(jī)影響區(qū)組織存在較大差異, 前進(jìn)側(cè)為窄條狀組織, 回退側(cè)為扁平塊狀組織；熱影響區(qū)組織發(fā)生了回復(fù)、 再結(jié)晶和粗化； 焊縫顯微硬度的最低值出現(xiàn)在前進(jìn)側(cè), 說明前進(jìn)側(cè)是焊縫的薄弱環(huán)節(jié)； 厚板焊接時, 沿板厚方向的熱機(jī)作用梯度過大, 造成焊縫金屬難以獲得優(yōu)良焊接性能, 這是厚板焊接較困難的原因。
關(guān)鍵字: 7A52鋁合金；厚板； 攪拌摩擦焊； 單道焊
7A52 aluminum alloy
（School of Mechanical and Electrical Engineering,
Central South University, Changsha 410083, China）
Abstract: Friction-stir welds of 7A52 aluminum plate of 25 mm thickness were completed in a single pass. The experiment results demonstrate that the adjusting scope of process parameters is very narrow when welding the plate of 25 mm thickness. When the rotating speed is 1 500 r/min and the welding speed is 40 mm/min, the good weld is achieved, and the tensile strength of the weld reaches 330 MPa, and the elongation reaches 9.6%. The welds consist of three different zones. The weld nugget zone consists of fine equiaxed grains which size is about 4 μm. Regarding to the thermo-mechanically affected zone on the two sides, the advancing side consists of narrow slate grains, while the retreating side consists of flat and nubby grains. The grains of heat affected zone have showed some reversion, recrystallization and growth characteristics. The min micro-hardness occurs on the advancing side. For the grads of thermo-mechanical action at the thickness direction is very large, it is difficult to achieve good welds as welding thick plate.
Key words: 7A52 aluminum alloy; thick plate; friction stir welding; single pass welding
