【正文】 ____ ____________ 指導(dǎo)教師簽字： 指導(dǎo)教師職稱： 評(píng)閱人評(píng)閱意見： _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _______ _____________________________________________________________________________________________________________________________________ ___ ___________________________________________________________ _________ _________________________ __ 評(píng)閱教師簽字： _________ ______ 評(píng)閱教師職稱： _________ _____ 答辯委員會(huì)評(píng)語： ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ __________ 根據(jù)畢業(yè)設(shè)計(jì) （ 論文 ） 的材料和學(xué)生的答辯情況，答辯委員會(huì)作出如下評(píng)定： 學(xué)生 畢業(yè)設(shè)計(jì) （ 論文 ） 答辯成績(jī)?cè)u(píng)定為： 對(duì)畢業(yè)設(shè)計(jì) （ 論文 ） 的特殊評(píng)語： ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ________ 答辯委員會(huì)主任 （ 簽字 ） ： 職稱： ______ __________ 答辯委員會(huì)副主任 （ 簽字 ） ： 答辯委員會(huì)委員 （ 簽字 ） ： ___________ ___________ ___________ __________ __________ ___________ ___________ ___________ __________ __________ ___________ ___________ ___________ __________ __________ 年 月 日 哈爾濱工業(yè)大學(xué)畢業(yè)設(shè)計(jì) （ 論文 ） 任務(wù)書 姓 名： 崔慶龍 院 (系 )： 材料科學(xué)與工程 專 業(yè)： 焊接技術(shù)與工程 班 號(hào)： 10729101 任務(wù)起至日期： 20xx 年 10 月 8 日至 20xx 年 6 月 29 日 畢業(yè)設(shè)計(jì)（論文）題 目： 厚板鈦合金窄間隙 TIG 焊接工藝研究 立題的目的和意義： 解決 4500mm級(jí)載人深海探測(cè)器制造過程中的焊接問題； 同時(shí)推動(dòng)厚板鈦合金在石油、化工等工業(yè)部門的廣泛應(yīng)用，提出一種 高效便捷、經(jīng)濟(jì)性好、用于焊接厚板鈦合金的方法 。 2) 78mm厚鈦合金試板的窄間隙 TIG 焊接工藝試驗(yàn)。 進(jìn)度安排： 50mm厚鈦合金板的試焊接，焊槍和保護(hù)裝置的設(shè)計(jì)和制造。 整理數(shù)據(jù)，撰寫論文，準(zhǔn)備答辯。 工藝試驗(yàn)結(jié)果表明，電流在 180A~240A 之間可以得到完整可靠的焊接接頭，焊接過程中 78mm 厚鈦合金試板的橫向收縮為 ，接頭區(qū)域狹窄且無明顯分區(qū)。 關(guān)鍵詞： 厚板鈦合金；窄間隙 TIG； 顯微 組織 ； 力學(xué)性能 ；溫度場(chǎng) 哈爾濱工業(yè)大學(xué)本科畢業(yè)設(shè)計(jì)（論文） II Abstract To solve the welding problem in manufacturing 4500mm level bathyscaphe and propel the development of thick titanium alloys structures in industrial, narrowgap TIG welding of thick titanium alloys is proposed as an efficient and economical method. Narrowgap TIG welding of TC4 by using Ti4Al2V filler metal with multilayer welding way, experiments have been done under the different sizes of groove and serials of currents and protecting gasflowrates, to determine the optimum welding parameters after the metallographic analysis and mechanical properties testing of welding joint. Results of welding technology experiment shows that the reliable joint can be obtained under the current of 180A240A, welding lateral contraction is about in 78mm titanium plate, and the joint is narrow with no marked division. Metallographic analysis of narrowgap TIG welding joint shows the rules of grain growth and microstructure characteristics, the changing of currents has little effect on the size of grain and microstructure. The tensile test shows that the tensile strength of joint is higher than the seam metal based on the theory of meshing strengthening in narrowgap welding of titanium alloys, the increase of current leads to the rising of perationratio, that also can contribute to increasing of strength. Results of Welding temperature field measurement show that the titanium alloys welding temperature field has its characteristics in the condition of narrowgap TIG welding. Keywords: thick titanium alloys。 welding temperature field 哈爾濱工業(yè)大學(xué)本科畢業(yè)設(shè)計(jì)（論文） III 目 錄 摘 要 ............................................................................................................................... I Abstract ............................................................................................................................. II 第 1 章 緒 論 ................................................................................................................ 1 課題背景及研究的目的和意義 ............................................................................ 1 厚板鈦合金焊接性分析 ........................................................................................ 2 國(guó)內(nèi)外研究現(xiàn)狀及分析 ........................................................................................ 3 MIG 多層多道焊 ............................................................................................. 3 窄間隙 TIG...................................................................................................... 4 電子束焊接 .......................................