本文選題：攪拌針 + 輔助熱源��； 參考：《南昌航空大學(xué)》2015年碩士論文

【摘要】：本文采用6種不同形貌的攪拌針和添加輔助熱源的方式對(duì)20mm厚的2024-T4鋁合金板材進(jìn)行攪拌摩擦焊試驗(yàn)。通過改變攪拌針形貌研究其對(duì)焊接時(shí)接頭溫度的影響,并測(cè)量了焊核區(qū)的形狀尺寸,分析了不同攪拌針形貌對(duì)焊縫塑性金屬流動(dòng)行為的影響;利用有限元分析軟件ANSYS對(duì)不同初始溫度下的焊縫溫度場(chǎng)進(jìn)行模擬,探討了溫度場(chǎng)的變化規(guī)律以及其對(duì)焊縫金屬流動(dòng)的影響。為優(yōu)化攪拌針的設(shè)計(jì)和厚板鋁合金的焊接提供理論參考。研究結(jié)果表明:攪拌摩擦焊焊接20mm厚2024鋁合金時(shí),合適的焊接工藝參數(shù)范圍較小。焊接熱輸入對(duì)厚板鋁合金材料的成形有較大影響,在旋轉(zhuǎn)速度為375r/min、焊接速度為37.5mm/min時(shí),可獲得無(wú)缺陷的焊接接頭。攪拌針形貌對(duì)塑性金屬流動(dòng)有很大影響。在攪拌針錐度為25°至15°范圍內(nèi),減小攪拌針基體錐度對(duì)焊縫金屬充分流動(dòng)有促進(jìn)作用。當(dāng)錐度減小至15°時(shí),攪拌針表面螺紋對(duì)塑性金屬的驅(qū)動(dòng)力減小;但攪拌針端部直徑增大、摩擦面積增加、產(chǎn)熱增加,致使接頭底部高溫區(qū)變寬、焊縫中塑化的金屬量以及攪拌針?biāo)鶖y帶的金屬量增多,從而焊核區(qū)塑性金屬擠壓作用增加。宏觀表現(xiàn)為焊核高度、寬度和面積都增大。多頭螺紋攪拌針會(huì)增強(qiáng)焊縫塑性金屬的流動(dòng)。相比單頭和雙頭螺紋,3頭螺紋攪拌針的金屬流動(dòng)通道更多,焊縫塑性金屬在軸向方向上的抽吸擠壓作用增強(qiáng),攪拌針端部脫離的高溫金屬量增多;但焊核周圍母材金屬的溫度未隨螺紋頭數(shù)的增減而變化,即焊核金屬周圍母材的抗變形能力相同。因此隨金屬量的增加,焊核區(qū)金屬向焊縫表層擴(kuò)張趨勢(shì)增強(qiáng),焊縫中的孔洞及疏松等焊接缺陷減少。采用合適的輔熱溫度對(duì)2024-T4鋁合金進(jìn)行焊接,可改善焊縫的孔洞缺陷,獲得無(wú)缺陷的焊接接頭。當(dāng)輔助熱源溫度為40℃時(shí),2024-T4鋁合金焊縫整體溫度升高,高溫區(qū)變寬,金屬軟化程度提升,塑化金屬量增多,攪拌針向焊縫底部抽吸的金屬量增加,使焊核區(qū)金屬橫向擠壓力增強(qiáng),阻力減弱;焊縫中“抽吸擠壓”作用增強(qiáng),塑性金屬會(huì)更趨向于在橫向方向流動(dòng),向上流動(dòng)動(dòng)能減小。宏觀表現(xiàn)為焊核區(qū)的面積、寬度和高度增加。
[Abstract]:In this paper, friction stir welding experiments of 2024-T4 aluminum alloy plate with 20mm thickness were carried out by using six kinds of stirring needles with different morphologies and adding auxiliary heat source. The effect of stirring needle morphology on weld temperature was studied, and the shape and size of nugget zone were measured, and the effect of different stirring needle morphology on the flow behavior of plastic metal was analyzed. The finite element analysis software ANSYS is used to simulate the weld temperature field at different initial temperatures. The variation of the temperature field and its influence on the flow of weld metal are discussed. It provides a theoretical reference for optimizing the design of mixing needle and welding of thick plate aluminum alloy. The results show that the suitable range of welding parameters is small when 20mm thickness 2024 aluminum alloy is welded by friction stir welding. The welding heat input has great influence on the forming of thick plate aluminum alloy material. When the rotation speed is 375 r / min and the welding speed is 37.5mm/min, the non-defect welded joint can be obtained. The shape of agitated needle has great influence on the flow of plastic metal. In the range of taper between 25 擄and 15 擄, reducing the taper of stirring needle matrix can promote the full flow of weld metal. When the taper is reduced to 15 擄, the driving force of the surface thread on the plastic metal decreases, but the diameter of the end of the stirring needle increases, the friction area increases and the heat production increases, which results in the widening of the high temperature area at the bottom of the joint. The amount of plasticized metal in the weld and the metal carried by the stirring needle increased, thus the plastic metal extrusion in the nuke zone increased. Macroscopically, the nugget height, width and area are increased. The multi-threaded stirring needle enhances the flow of the plastic metal in the weld. There are more metal flow channels in the mixing needle with single or double screw thread, the suction and extrusion effect of the plastic metal in the axial direction is enhanced, and the amount of high temperature metal detached from the end of the stirring needle is increased. However, the temperature of the base metal around the nugget does not change with the increase or decrease of the number of thread heads, that is, the deformation resistance of the base metal around the nugget metal is the same. Therefore, with the increase of the amount of metal, the tendency of metal expansion into the surface of weld increases, and the defects such as porosity and porosity in the weld decrease. When 2024-T4 aluminum alloy is welded with appropriate auxiliary heating temperature, the hole defects of the weld can be improved and the welded joints without defects can be obtained. When the auxiliary heat source temperature is 40 鈩，

本文編號(hào)：2001883