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目前市面上的工業風扇葉片都是以鋁合金為主，這是因為鋁合金材料的密度低且強度高，熱電導率高，耐腐蝕的能力強，擁有較好的物理特性及力學方面性能。

      但是因為焊接方法和焊接工藝參數選取不當，會導致葉片焊接以后因力過于集中化而產生嚴重的機械變形，或者因焊縫氣孔、夾渣和未焊透等等不足，致使焊縫金屬裂紋或者材質疏松，從而嚴重的影響產品質量與性能。

      鋁為銀白色輕金屬，有良好的可塑性，比較高的導電性、導熱性，還具有抗氧化及抗腐蝕性能。鋁極易氧化產出三氧化二鋁薄膜，在焊縫中生出夾雜物，而破壞金屬的連續性及其均勻性能，降低它的機械性能及耐腐蝕的性能。

      這是在焊接鋁合金是很難避免的事，所以我們需要了解鋁合金焊接時應該注意的地方。

      （1）易被氧化。空氣中，鋁易和氧化合，產生致密的三氧化二鋁薄膜（厚度約0.1-0.2mm），熔點很高（約2050°C），大大地超過鋁及鋁合金的熔點（約600°C左右）。

      （2）容易產生氣孔。鋁及鋁合金焊在接時生出氣孔主要因素是氫，由于液態鋁可溶解大量氫，但固態的鋁基本不會溶解氫，所以當熔池溫度快速冷卻與凝固的時候，氫來不及逸出，易在焊縫里面形成氣孔。氫氣孔當前難完全免除，氫的來源有很多，

      （3）焊縫時候變形及形成裂紋的傾向較大。鋁線膨脹系數及結晶收縮率都約比鋼要大出兩倍，易生成比較大的焊接變形內應力，剛性較大的結構將會加速熱裂紋的生成。

      （4）合金元素的蒸發的燒損。鋁合金中含有低沸點的元素（如鎂、鋅、錳等），在高溫電弧作用下，極易蒸發燒損，從而改變焊縫金屬的化學成分，使焊縫性能下降。

      （5）溫強度和塑性低。高溫時鋁的強度和塑性很低，破壞了焊縫金屬的成形，有時還容易造成焊縫金屬塌落和焊穿現象。

      當然這只是焊接時應該注意的問題，這些了解后，我們需要明白工業風扇葉片焊接工藝方法。

      （1）焊前的準備

      運用化學和機械的方法，嚴格的清理焊縫坡口兩側的表面氧化性膜。

      （2）確定裝配間隙和定位焊間距

      施焊的過程中，鋁板受熱膨脹，使焊縫坡口間隙減小，焊前裝配間隙若留得太小，焊接過程中便會引起兩板坡口的重疊，增加焊后板面不平度及變形量裝。配間隙若過大，施焊困難，并有燒穿的可能性。一定的定位焊間距可保證所需要的定位焊間隙，選擇合適的裝配間隙和定位焊間距，為減少變形的有效措施。

      （3）選擇焊接的設備

      當前市場上焊接產品種類較多，通常更好用交流鎢極氬弧焊（即TIG焊）。它為在氬氣保護作用下，利用鎢電極及工件問產生的電弧熱熔化母材及填充焊絲的一種焊接方法。

      （4）選擇焊絲通常選用301純鋁焊絲及311鋁硅焊絲。

      （5）選取焊接方法參數通常以左焊法進行，焊炬和工件會成60°角。焊接厚度15mm時，用右焊法進行，焊炬與工件會成90°角。焊接的壁厚在3mm以上的時候，開V形坡口，夾角是60°～70°，間隙不可大于1mm，用多層焊的方法去完成。壁厚在1．5mm以下的時候，不開坡口，也不留間隙，也不會加填充絲。焊固定管子對接接頭的時候，若管徑為200mm，壁厚為6mm的時候，宜采用直徑為3～4mm的鎢極，用220～240A的焊接電流，直徑為4mm的填充焊絲，用1～2層焊完。

At present, the industrial fan blades on the market are mainly made of aluminum alloy, because of its low density and high strength, high thermal conductivity, strong corrosion resistance, and good physical and mechanical properties. However, improper selection of welding method and welding process parameters will lead to serious mechanical deformation of Blade due to over-concentration of welding force, or due to insufficient weld porosity, Slag Inclusion and incomplete penetration, etc. The quality and performance of the products are seriously affected by the weld metal crack or material porosity. Aluminum is a silver-white light metal with good plasticity, high conductivity, thermal conductivity, oxidation resistance and corrosion resistance. Aluminum is highly oxidised to produce aluminium oxide films, which produce inclusions in welds, which damage the metal's continuity and uniformity, reducing its mechanical properties and corrosion resistance. This is in the welding of aluminum alloy is very difficult to avoid, so we need to understand the aluminum alloy welding should pay attention to the place (1) easy to be oxidized. In the air, aluminum easily oxidizes, resulting in a dense aluminium oxide film (thickness about 0.1-0.2 mm) with a very high melting point (about 2050 °c) , which greatly exceeds the melting point of aluminum and its alloys (about 600 °c) (2) prone to blowhole. Hydrogen is the main factor for the formation of pores in aluminum and aluminum alloys during welding. Because liquid aluminum can dissolve a large amount of hydrogen, but solid aluminum can hardly dissolve hydrogen, so when the bath temperature is rapidly cooled and solidified, hydrogen can not escape POROSITY is easily formed in the weld. At present, it is difficult to completely eliminate the hydrogen hole, the hydrogen source has many, (3) when the weld deformation and the forming crack tendency is big. Aluminum Linear Expansion Coefficient and crystallization shrinkage are about twice larger than steel, easy to generate greater welding deformation stress, rigid structure will accelerate the formation of hot cracks (4) burning of the alloy elements by evaporation. Aluminum alloys contain low boiling point elements (such as magnesium, zinc, manganese, etc.) . Under the action of high temperature arc, it is easy to evaporate and lose, thus changing the chemical composition of the Weld metal and reducing the weld performance (5) low temperature strength and plasticity. The strength and plasticity of aluminum is very low at high temperature, which destroys the formation of weld metal and sometimes causes the collapse and wear of weld metal. Of course, this is only welding should pay attention to the problem, these understanding, we need to understand the industrial fan blade welding process (1) the preparation before welding, the use of chemical and mechanical methods, Strictly Clean The weld groove on both sides of the surface oxide film (2) to determine the assembly gap and the positioning welding distance. During the welding process, the aluminum plate is expanded by heat, which reduces the gap between the welding seams and the groove. If the pre-welding assembly gap is too small, the overlap of the groove between the two plates will occur during the welding process Increase the flatness and deformation of the welded plate. If the clearance is too large, it is difficult to weld, and there is the possibility of burning through. A certain distance between the two welds can ensure the required distance between the two welds, and the suitable distance between the two welds can be selected as an effective measure to reduce deformation (3) choose welding equipment, there are many kinds of welding products in the market, usually it is best to use AC TIG (TIG welding) . The utility model relates to a welding method for welding a base metal and a filling welding wire by using an electric arc generated by a tungsten electrode and a workpiece under the protection of Argon Gas (4)301 pure aluminum wire and 311 aluminum-silicon wire are usually used for selecting welding wire (5) welding method parameters are usually selected by left welding method, welding torch and workpiece will be 60 angle. When the thickness of welding is 15mm, the right welding method is used, and the welding torch and the workpiece will form a 90 angle. When the thickness of the welding wall is more than 3mm, open the V-groove, the angle is 60 ~ 70, the gap can not be more than 1mm, with multi-layer welding method to complete. When the wall thickness is less than 1.5 mm, there is no groove, no gap and no filling wire. When welding the butt joint of fixed pipe, if the pipe diameter is 200mm, the wall thickness is 6mm, should use the tungsten electrode with the diameter of 3 ~ 4mm, the welding current of 220 ~ 240A, the filler wire with the diameter of 4mm, and use 1 ~ 2 layers to weld.