【正文】 has reached 180 176。. Tensile test, fracture location are in the softening zone near the fracture surface dull gray with obvious necking, ductile lowest impact energy weld, heat affected zone followed. Microindentation shear tests rate as close to the weld to the base material, and gradually decreased. Weld microstructure is mainly α (Al) + β (Mg2 Al3) Lord, and coarse grains, stomata more than other areas, and large. The results show that for 5052 aluminum alloy welding, MIG welding process using optimized, relatively good performance of welded joints. key words： Aluminum； MIG welding； Welded joints； Process Test 西南交通大學(xué)本科 畢業(yè)設(shè)計 (論文 ) 第 VI 頁 目錄 第 1 章 緒論 ........................................................................................................................ 1 前言 ....................................................................................................... 1 鋁合金的概述及分類 ................................................................................ 1 概述 ................................................................................................................. 1 分類 ................................................................................................................. 2 鋁合金焊接 ............................................................................................. 3 鋁合金的焊接特點 ......................................................................... 3 鋁合金的焊接方法 ......................................................................................... 4 焊接材料的選用原則 ..................................................................................... 5 MIG 焊簡介 ............................................................................................. 6 焊的基本概念 ......................................................................................... 6 焊的主要特點 ........................................................................................ 7 焊熔滴過渡特點 ..................................................................................... 7 焊接存在的問題與難點 ......................................................................... 8 MIG 焊的工藝參數(shù) ........................................................................................ 9 國內(nèi)外鋁合金的焊接新技術(shù) ................................................................... 10 本次論文的研究內(nèi)容及意義 ................................................................... 12 第 2 章 試驗材料及方法 .................................................................................................. 14 試驗材料 ................................................................................................................... 14 MIG 焊工藝試驗 ............................................................................................. 15 焊前準備 ...................................................................................................... 15 焊接設(shè)備及操作方法 .................................................................................. 16 焊接速度的測定 ........................................................................................... 17 試驗方案設(shè)計 .............................................................................................. 17 組織和性能試驗方法 ............................................................................. 19 顯微組織分析 ............................................................................................... 19 硬度試驗 ...................................................................................................... 20 拉伸試驗 ...................................................................................................... 21 彎曲試驗 ...................................................................................................... 22 沖擊試驗 ...................................................................................................... 23 微型剪切試驗 .............................................................................................. 24 第 3 章 試驗結(jié)果及其分析 .............................................................................................. 26 焊縫宏觀形貌及分析 ............................................................................. 26 焊接接頭顯微組織及其分析 .................................................................... 27 維氏硬度 ............................................................................................... 30 拉伸試驗及斷口分析 .............................................................................. 33 彎曲試驗結(jié)果及分析 .............................................................................. 34 沖擊試驗結(jié)果及分析 ............................................................................. 36 微型剪切數(shù) 據(jù)及分析 ............................................................................. 37 第 4 章 對比分析及綜合分析 ............................................................................................ 39 MIG 焊工藝試驗綜合分析 ....................................................................... 39 與攪拌摩擦焊接頭性能的對比 ................................................................. 41 西南交通大學(xué)本科 畢業(yè)設(shè)計 (論文 ) 第 VII 頁 拉伸試驗數(shù)據(jù)對比 ....................................................................................... 41 沖擊試驗數(shù)據(jù)對比 ....................................................................................... 41 彎曲試驗數(shù)據(jù)對比 ....................................................................................... 42 硬度試驗數(shù)據(jù)對比 ....................................................................................... 42 金相對比 ...................................................................................................... 43 綜合分 析 .................................................................................................... 44 結(jié) 論 ..............................................