【正文】 copper and copper alloy uniform, bined with the zone of transition。s Weldment . Choice of welding wires to nickel welding wire (HS201 ), and choose singleV. 　Test results and analysisMetallographic and analysis diagram 1 （ a ) Copper side of base metal, its organization as α solid (. a single solid), from the entire picture, not any defects, metal. Figure 1 ( b ) TIG welding ( HS201 wire) in microscopy near copper base metal side of fusion line organization metallographic figure. From figure 1 ( b ) can see the fusion line of pure copper and wire fusion. Performances of the for copper side α phase grain grow abnormally. From the entire picture and see no obvious deficiencies. By figure 1 ( c ) visible, metallographic figure for the weld area of the organization chart, from the picture to see entire weld basically to cylindrical shape. Figure 1 ( d ) carbon steel and copper weld Centre districts metallurgical structure diagram, picture organization still as columnar Crystal organization. Good tough plastic. Figure 1 ( e ) carbon steel base metal side of fusion line metallographic figure, as can be seen from figure carbon steel side of grain is an exception, basic to plate strip martensite. Strength, high hardness, toughness and ductility, significantly lower. Figure 1 ( f ) metallurgical structure diagram for carbon steel side of the heat affected zone of organizations, from roughly graph can be seen in the heat affected zone of organizations generally include fine grain and coarse grain area in two parts, metal. From the above picture, you can find red copper and steel side fusion of good.The welding process to choose a fill material directly to the steel and copper or copper alloy welded together with. As a result of steel and copper alloys, there are many kinds of materials in some of the elements in the transition to weld makes steel and copper or coppergold and weldability, so should use with steel and copper and steel desk gold has a good welding of metal ( as nickel electrode or nickelcopper alloy Rod ) as fill material. The welding parameters smaller, welding area of cooling rate is large, or welding speed faster, liquid copper on the steel surface infiltration and seepage is relatively small, only in grain boundary edges produce capillary wetting, also does not constitute the infiltration of along grain boundaries。s development. Copper and steel weldability featuresCarbon steel and copper have good weldability. The melting point of iron and copper, thermal conductivity, linear expansion coefficient, etc, the difference is large, this is the two materials for welding of adverse factors。s welding is valued people39。s amount used is also quite big. Selects the material should be can satisfy the work requirement the exotic material, the independent employment one material cannot satisfy in the practical application frequently each kind of request. Therefore in the modern engineering structure, we not only needs to carry on the welding to the massive homogeneous materials, simultaneously also needs to carry on the welding to the considerable amount heterogeneous material, uses the heterogeneous material welding structure in the project and the manufacture, not can only satisfy the different working condition to the material quality various requirement, moreover can also save the noble metal, reduces the structure overall cost, full display different material performance superiority. In some kind of situation, the heterogeneous material structure39。（3）經(jīng)金相檢驗，焊縫內(nèi)部組織均勻；可以得到良好的焊縫組織，紫銅和紫銅熔合區(qū)過渡均勻，結合良好；碳鋼與紫銅側熔合均勻，紫銅與碳鋼熔合線平直，無孔洞，且Cu和Fe相互之間有一定程度擴散，熔合區(qū)為冶金結合。（1）紫銅與低碳鋼的物理性能和化學成分差異很大，銅鋼焊縫易產(chǎn)生很多缺陷，如裂紋、未熔合、氣孔等，但只要執(zhí)行合理的焊接工藝，熟練掌握焊接操作技術，仍能獲得滿意的銅鋼焊接接頭。本章結論　本論文通過TIG焊工藝對紫銅和鋼異種材料進行焊接，為銅和低碳鋼異種材料焊接的發(fā)展提供理論依據(jù)和實驗基礎。由于鋼和銅合金的種類很多，母材中有些合金元素過渡到焊縫中時，會使鋼與銅或與銅臺金的焊接性變差，所以應選用與鋼和銅及鋼臺金均具有良好焊接性的金屬(如鎳基焊條或鎳銅合金焊條)作填充材料。從以上圖片中可以發(fā)現(xiàn)紫銅側和鋼側熔合的良好。強度、硬度高，而塑性、韌性明顯降低。有良好的韌塑性。由圖1（c）可見，金相組織圖為焊縫區(qū)組織圖，從圖片上看整個焊縫基本上以柱狀形態(tài)結晶。特征表現(xiàn)為紫銅側α相晶粒異常長大。圖1（b）TIG 焊（HS201焊絲）在顯微鏡下的靠近紫銅母材側的熔合線組織金相圖。TIG焊幾乎可用于所有鋼材、有色金屬及其合金的焊接，特別適合于化學性質活潑的金屬及其合金。因此，當銅鋼焊縫強度、塑性顯著下降，并且焊件中存在內(nèi)應力時，就在接頭的脆弱部位形成熱裂，但只要執(zhí)行合理的焊接工藝，熟練掌握焊接操作技術，仍能獲得滿意的銅鋼焊接接頭。這可以說明，鋼與銅或銅合金之間，可以采用各種方法進行焊接。鐵與紫銅的熔點、導熱系數(shù)、線膨脹系數(shù)等、差別較大、這是兩種材料焊接時的不利因素；但鐵與銅的原子量、原子半徑、點陣常數(shù)等化學性能、又比較近，對焊接是有利的。本課題嘗試采用鎢機氬弧焊（TIG）對低碳鋼、銅異種材料進行焊接，為低碳鋼和銅異種材料焊接的發(fā)展提供理論依據(jù)和實驗基礎。異種材料的焊接日益受到人們的重視，具有廣闊的應用前景，近年來在航天、石油化工、電站鍋爐、核動力、造船及其他一些領域獲得越來越廣泛的應用。因此在現(xiàn)代工程結構中，我們不僅需要對大量的同種材料進行焊接，同時也需要對相當數(shù)量的異種材料進行焊接，在工程中及制造中采用異種材料焊接結構，不僅能滿足不同工作條件對材質的不同要求，而且還能節(jié)約貴重金屬，降低結構整體成本，充分發(fā)揮不同材料的性能優(yōu)勢。JOINING 2006 (4) 1620附 錄1現(xiàn)在工程中許多零件需要工作在高溫或低溫、腐蝕介質、電磁場或放射性環(huán)境中，其中有色金屬材料的用量也比較大。在實驗過程中，得到了王會學、趙偉等同學的大力配合與協(xié)作，也得到了其他同學的幫助與指導，在此一并表示感謝。在此，向導師的培養(yǎng)和教育表示崇高的敬意和衷心的感謝。致 謝本文是在導師楊德云老師的悉心指導下完成的，導師科學客觀、一絲不茍的工作態(tài)度令學生受益頗深。（2）通過焊接檢驗可知，焊縫具有良好的力學性能以及機械性能，從而證明銅與不銹鋼可以通過一些焊接方法和合理的焊接工藝將其焊接在一起，并得到性能良好的焊接接頭。（1）紫銅與不銹鋼的物理性能和化學成分差異很大，銅與不銹鋼鋼焊縫易產(chǎn)生很多缺陷，如裂紋、未熔合、氣孔等，主要缺陷是裂紋。從而證明了銅與不銹鋼異種材料可以通過某種焊接方法將其良好的焊接在一起，并通過調整合適的焊接參數(shù)的成型及力學性能良好的焊接接頭。但由于銅與不銹鋼中所含成分較多，在焊接時，母材中的一些合金元素會過渡到焊縫中，形成一些組織（如低熔點共晶物等），嚴重影響了焊接接頭力學性能，使得接頭性能下降。 本章總結 從以上圖片中可以發(fā)現(xiàn)紫銅側和不銹鋼側熔合的良好。在焊縫處不銹鋼組織為樹枝晶和枝晶間的少量鐵素體，紫銅則仍為單項固溶體組織。不銹鋼側組織：奧氏體不銹鋼母材組織為奧氏體或奧氏體和少量的鐵素體，熔合線和熱影響區(qū)交界較明顯，不銹鋼側母材熱影響區(qū)組織較為狹窄，組織為奧氏體和帶狀鐵素體，不銹鋼母材未受熱影響區(qū)組織為奧氏體和少量帶狀分布的鐵素體以及一些顆粒碳化物。b）、c）和d）均為焊縫組織金相圖，由b）和c）可以看出不銹鋼成分與紫銅成分較為均勻混合，由此可見，不銹鋼與銅焊接時，銅與不銹鋼均流入焊縫中，與填充材料（鎳基焊絲HS201）混合充分形成焊縫。 TIG焊焊接接頭組織微觀顯示圖 a） b） c） d）圖36 TIG焊的焊縫組織金相顯微圖 圖36中，a）、b）和d）均為放大100倍的金相組織圖，c）圖為放大400倍的焊縫組織金相圖。所得焊件正面成形如圖34所示；背面成形如圖35所示。3. TIG焊時所用的實驗數(shù)據(jù)： 材料板厚：2~3mm，預熱溫度：300℃，鎢極直徑：2~3mm，焊絲直徑：，噴嘴直徑：8~10mm，焊接電流：175~225A，氬氣流量：6~10（L∕min），電源極性：直流正接，焊接速度：∕s，送絲速度：2mm∕s，破口形式：不銹鋼45176。銅的導熱率比鐵大711倍，厚度越大，散熱越快，越難達到熔化溫度。所得焊件銅不預熱背面成形如圖33所示。2. TIG焊時所用的實驗數(shù)據(jù)： 材料板厚：2~3mm，預熱溫度：不預熱，鎢極直徑：2~