【正文】 要有的態(tài)度和心態(tài)，首先做學(xué)問要一絲不茍，對于發(fā)展過程中出現(xiàn)的任何問題和偏差都不要輕視，要通過正確的途徑去解決，在做事情的過程中要有耐心和毅力，不要一遇到困難就達(dá)退堂鼓，只要堅(jiān)持下去就可以找到思路去解決問題的。而且要學(xué)會與人合作，這樣做起事情來就可以事倍功半。 在這里，要特別感謝大學(xué)三年學(xué)習(xí)期間給我諸多教誨和幫助的洛陽理工學(xué)院的各位老師，感謝閆紅彥老師、張立峰老師、崔琦老師、閆紅彥老師、宋聯(lián)美老師，你們給予我的指導(dǎo)和教誨我將永遠(yuǎn)記在心里感謝在大學(xué)三年學(xué)習(xí)期間給我傳授諸多專業(yè)知識的焊接教研室的各位老師，感謝閆紅彥老師、崔琦老師、張立峰老師、宋聯(lián)美老師、閆紅彥老師、給予我的指導(dǎo)和幫助！感謝和我一起生活三年的室友，是你們讓我們的寢室充滿快樂與溫馨， “君子和而不同”，我們正是如此！愿我們以后的人生都可以充實(shí)、多彩與快樂！感謝我的同學(xué)們，謝謝你們給予我的幫助！回首本人的求學(xué)生涯，父母的支持是本人最大的動力。父母不僅在經(jīng)濟(jì)上承受了巨大的負(fù)擔(dān)，在心里上更有思子之情的煎熬與望子成龍的期待。憶往昔，每次回到家時父母的欣喜之情，每次離家時父母的依依不舍之眼神，電話和信件中的殷殷期待和思念之語，皆使本人刻苦銘心，目前除了學(xué)習(xí)成績尚可外無以為報(bào)，希望以后的學(xué)習(xí)、工作和生活能使父母寬慰。參考文獻(xiàn)[1] 張 淮、孫柏洲，小議CO2氣體保護(hù)焊焊接工藝及其飛濺的控制,生產(chǎn)一線，（哈爾濱汽輪機(jī)廠有限責(zé)任公司）[2] 趙琳，淺談CO2氣體保護(hù)焊，特檢視窗，2009：7172[3] 李春國、王惜寶、孫洪玲，CO2氣體保護(hù)焊實(shí)心焊絲的應(yīng)用現(xiàn)狀和發(fā)展動態(tài)(天津大學(xué)材料科學(xué)與工程學(xué)院,天津300072)，焊接技術(shù)第36卷第2期2007：14[4] 李玉生，青藏線機(jī)車車輛用Q345鋼材的焊接工藝研究(中國南車集團(tuán)戚墅堰機(jī)車車輛工藝研究所,江蘇常州213011)，機(jī)車車輛工藝，第6期 2004：2931 [5] 朱張校，工程材料，[M].北京：清華大學(xué)出版社，2001：163170.[6] 李亞江、王娟，氣體保護(hù)焊工藝及應(yīng)用，化學(xué)工業(yè)出版社，2009[7] 杜國華，新編焊接工藝500問，機(jī)械工業(yè)出版社，2009[8] 韓國明，焊接工藝?yán)碚撆c技術(shù)第二版（焊接工程師系列教程），機(jī)械工業(yè)出版社，2007[9] 殷樹言等，CO2焊接設(shè)備原理與調(diào)試，機(jī)械工業(yè)出版社，2000[10] 李亞江，焊接冶金學(xué)—材料焊接性，機(jī)械工業(yè)出版社，2006[11] 楊春利、林三寶等，電弧焊基礎(chǔ)，哈爾濱工業(yè)出版社，2003[12] 陳裕川，焊接工藝設(shè)計(jì)與實(shí)例分析，機(jī)械工業(yè)出版社，2010[13] 彭友祿，焊接工藝，人民交通出版社，2002[14] 陳伯蠡，焊接工程缺陷分析與對策第二版，機(jī)械工業(yè)出版社， 2006[15] 崔忠圻，金屬學(xué)與熱處理第二版，機(jī)械工業(yè)出版社，2004[16] 殷樹言，氣體保護(hù)焊技術(shù)問答，機(jī)械工業(yè)出版社，2003[17] 劉云龍，CO2氣體保護(hù)焊技術(shù)，機(jī)械工業(yè)出版社，2009[18] 李榮雪，焊接檢驗(yàn)第二版，機(jī)械工業(yè)出版社，2007[19] 周振豐、張文鉞，焊接冶金與金屬焊接性，機(jī)械工業(yè)出版社，1980[20] 周炳森，新編焊接設(shè)備選型與焊接材料選用實(shí)用手冊，中國知識版社，2006[21] 李亞江，焊接材料的選用，化學(xué)工業(yè)出版社，2004外文資料翻譯WELDABILITY ANALYSIS OF Q345 STEELLOW STEEL ALLOY STRUCTURE OF WELDABILITY ANALYSIS16Mn and 15MnV belong to the lowalloy steel hot rolled steel, these steel prices lower, and has satisfied the mechanical properties and processing performance, first of all to analyze this type of steel welding, welding on two points of typically Bianxian questions: First, due to a variety of welding defects, such types of steel for the main crack。 Second, changes in material properties when welding on the type of steel is mainly embrittlement problem.1. Crack(1) Thermal crack: hot rolled carbon content generally lower, while the higher manganese content, so they Mn / S parison, and has good resistance to thermal cracking performance. Normally, the weld hot cracking does not occur, but when the material ponent failure or serious segregation of carbon, sulfur content higher, Mn / S ratio is low, prone to hot cracking. Manganese in the steel with manganese sulfide sulfur to reduce the harmful effects of sulfur and enhance the performance of steel thermal cracking.(2) Cold crack: the crack depends on the cold steel, hardened steel, the tendency of the tendency toward hardening just depends on its chemical position. Hot rolled steel contains a small amount of alloying elements because of its low carbon steel when the carbon equivalent is slightly higher than some, so this low carbon steel hardened tend to be bigger than that, but with the increase of steel strength level, the increase in alloying elements, it The hardening tendency increases should be based on the form and steel fittings to adjust the line thickness of the energy, preheating and postheat temperature, to control the heataffected zone of the cooling rate, while reducing the amount of weld metal hydrogen and other measures to prevent cold cracks.(3)Reheat cracking: Considerations from the chemical position of steel, hot rolled steel does not contain as strong carbide forming elements, so again not sensitive to hot cracking, but also by increasing the preheating temperature and post weld heat such measures immediately after to prevent hot cracking.2. Embrittled(1)Hot zone embrittlement: hot rolled steel welding near the weld zone is heated to above 100 ℃ coarse grain zone, easy to produce grain growth phenomenon is worst in welded joints of plastic parts, often to withstand the stress the role of the damage. To prevent the overheating zone embrittlement measures is to improve the cooling rate, in particular, to improve the stability of austenite within the minimum cooling rate, shorten the residence time in this temperature range, reduce or prevent the emergence of austenite to raise steel impact toughness, but also to prevent the overheating zone coarsegrained brittle, should not be using too much energy input.(2) Heat should be crisp: the heat should be crisp is the thermal stress during the welding process because the plastic deformation to dislocation multiplication, while nitrogen and carbon atoms induced rapid proliferation of dislocation accumulation area, there should be crisp of heat. 16Mn and 15MnV these two types of steel has got to be brittle tendency of heat, eliminating welding heat should be crisp and effective measures of postweld annealing.LOW ALLOY STRUCTURAL STEEL WELDING1. Welding preparation:(1) The design of groove type of welding should be avoided not through or partial penetration of the groove, but also to minimize the weld crosssectional area to reduce the residual stress in joints, it can also reduce the consumption of welding materials .(2) Groove to note when using thermal cutting edge of the base metal will prevent the formation of a certain depth of the hardened layer, this hardened layer of low ductility often cold cracking source.(3) Weld area before welding steel to eliminate surface moisture, groove surface oxide, rust, grease and other contaminants.(4)Before use welding materials manufacturer remended specifications should be dry.(5)Orientation and assembly, and the formal weld seam must be the same type of electrode.2. Welding heat input of choice:Line energy parameters is welding current, arc voltage and welding speed. Lowalloy structural steel welding, heat input parameters to the need to ensure that joint penetration and weld, but also consider their joint performance. Welding of low carbon con