摘要

本文針對(duì)摩托車鋁合金車架的可焊性較差，在焊接過程中易產(chǎn)生焊不透、未熔合、夾雜、氣孔、熱裂紋等缺陷，特別是接頭的軟化造成母材的浪費(fèi)和應(yīng)用的限制等問題，對(duì)摩托車車粿@Ｓ玫腖Y12鋁合金的焊接工藝進(jìn)行了研究，為鋁合金在摩托車行業(yè)中的應(yīng)用提供了試驗(yàn)依據(jù)，對(duì)于擴(kuò)大鋁合金的應(yīng)用具有重要的意義和實(shí)際應(yīng)用價(jià)值。
通過一系列的試驗(yàn)，研究了LY12鋁合金的焊接工藝，得出焊接接頭成型較好的工藝參數(shù)。對(duì)LY12焊接接頭的力學(xué)性能（強(qiáng)度、硬度和塑性）進(jìn)行了測(cè)試；然后利用金相顯微鏡對(duì)LY12鋁合金焊接接頭及其附近區(qū)域的顯微組織進(jìn)行了分析；并且對(duì)于焊縫的軟化和出現(xiàn)裂紋和氣孔等缺陷也進(jìn)行了分析。
通過對(duì)LY12鋁合金的焊接工藝試驗(yàn)的分析，本文得出：MIG焊的工藝參數(shù)對(duì)焊縫成形有明顯的影響，采用合適的工藝參數(shù)可以獲得較高質(zhì)量的焊縫。
通過對(duì)LY12焊接接頭力學(xué)性能、焊縫組織，焊縫缺陷的分析，本文得出：LY12焊接接頭的硬度、強(qiáng)度和塑性均低于母材的對(duì)應(yīng)力學(xué)性能，且在距焊縫中心約9～13mm處的熱影響區(qū)發(fā)生了軟化。軟化區(qū)產(chǎn)生的主要原因是：該區(qū)強(qiáng)化相粒子在焊接熱循環(huán)過程中發(fā)生了過時(shí)效，產(chǎn)生聚集粗化。經(jīng)過一定的自然時(shí)效，接頭的強(qiáng)度和延伸率有一定的恢復(fù)；LY12鋁合金具有一定的結(jié)晶裂紋敏感性。在MIG焊下，LY12鋁合金的氣孔敏感性較大，焊接方法、環(huán)境相對(duì)濕度、試板表面狀態(tài)、保護(hù)氣體成分及焊接規(guī)范對(duì)LY12鋁合金的氣孔敏感性有很大的影響。通過控制各種水分的來源并采用合適的焊接規(guī)范可減小LY12的氣孔敏感性。

關(guān)鍵詞：LY12鋁合金，焊接工藝，顯微組織，裂紋，氣孔











ABSTRACT

This passage be aimed at the low capability of aluminum alloy of Motorcycle pieces,producing a lot of blemishs in welding process,for example,the welding is not deeply,lard,pore,hot crack and so on ,in particular joints caused a softening of base metal waste and application of restrictions and other issues, Therefore,the article explored the welding technology of LY12 aluminum alloy that is often used in Motorcycle Frame.This research provides experiment data for the application of aluminum alloys in Motorcycle industry. The work also has important practical value and Significance to the further use of aluminum alloys.
The mechanical properties of LY12 welded joint were also tested. In order to make further research of the different performance between welded joint and base metal of LY12 alloy, the microstructure characteristics were studied by means of advanced test methods including optics microscope. Furthermore, the article also covered research of effects about different welding processes and parameters on LY12 alloy bead sizes and the softening and the weld cracks and pore defects also were analyzed.
The result of the LY12's aluminum welding technology test shows that: MIG welding process parameters of the weld have great effect on weld shape, using appropriate technical parameters will get welds of higher quality.
The study of microstructure and properties of LY12 welding joint indicates that hardness, tensile strength and plasticity of the joint are lower than the relevant properties of base metal and the weakest point of welded joint is in the soften zone of HAZ, 9~13mm away from the weld center. It is formed due to the overaging of the main strengthening phase particle, which aggregates and coarsens during the influence of welding heat. After some extent of natural seasoning, tensile strength and plasticity of the joint are restored;LY12 aluminum alloy has a crystal crack sensitivity. In the TIG and MIG welding, LY12 aluminum alloy has larger stomatal sensitivity, and welding method, relative humidity and try to board surface, the protection of welding gas composition and norms of the LY12 aluminum alloy greatly affect stomatal sensitivity .Stomatal sensitivity of LY12 can be reduced by controlling the various water sources and using the appropriate welding standards

Key Words: LY12 alloy, welding technology, microstructure,hot cracking, porosity



目 錄

中文摘要 Ⅰ
ABSTRACT Ⅱ
1緒論 1
1.1 課題研究的背景和意義 1
1.2 本課題研究內(nèi)容 2
2 LY12鋁合金的焊接性分析、焊接方法及試驗(yàn)材料的確定 3
2.1 LY12鋁合金焊接母材介紹 3
2.2 鋁合金焊接方法選擇 3
2.2.1國內(nèi)外鋁合金焊接的先進(jìn)工藝概述 3
2.2.2 鋁合金常用焊接方法概述 4
2.3 焊接材料 5
2.3.1焊絲 5
2.3.2保護(hù)氣體 6
2.4鋁合金的焊接性 6
3 LY12鋁合金焊接試驗(yàn) 8
3.1焊前清理 8
3.1.1 機(jī)械清理 8
3.1.2 化學(xué)清理 8
3.2焊接設(shè)備 8
3.2.1焊機(jī) 8
3.2.2焊接工藝參數(shù) 8
3.3焊接測(cè)試 9
3.3.1焊接接頭試樣的切取 9
3.3.2 焊接接頭試樣的制備 9
3.3.3 測(cè)試手段 10
4 實(shí)驗(yàn)結(jié)果及分析 11
4.1 焊接工藝對(duì)LY12鋁合金焊縫尺寸的影響 11
4.1.1 MIG 焊焊接參數(shù)對(duì)角接焊縫尺寸的影響 11
4.1.2 MIG焊焊接參數(shù)對(duì)搭接焊縫尺寸的影響 12
4.1.3 MIG 焊焊接參數(shù)對(duì)對(duì)接焊縫尺寸的影響 13
4.2 接頭力學(xué)性能試驗(yàn) 14
4.2.1 接頭的拉伸與彎曲試驗(yàn) 15
4.2.2 接頭硬度試驗(yàn) 15
4.3 焊接接頭組織與性能分析 16
4.3.1 金相分析 16
4.3.2 接頭性能分析 17
4.4焊接缺陷的形成機(jī)理及防止措施 17
4.4.1 LY12鋁合金裂紋敏感性 17
4.4.2 LY12鋁合金的氣孔敏感性 18
5 結(jié)論 21
致謝 22
參考文獻(xiàn) 23