分析工业焊接中高热电导率铝合金材料

1、. 分析工业焊接中高热电导率铝合金材料铝是银白色的轻金属,具有良好的塑性、较高的导电性和导热性,同时还具有抗氧化和抗腐蚀的能力。铝极易氧化产生三氧化二铝薄膜,在焊缝中容易产生夹杂物,从而破坏金属的连续性和均匀性,降低其机械性能和耐腐蚀性能。Aluminum is a silvery white metal, good plasticity, high electrical conductivity and thermal conductivity, but also has the ability of oxidation resistance and corrosion resistance

2、. Aluminum to produce 3 oxidation 2 aluminium oxide thin film, prone to inclusions in the weld, which destroy the continuity and uniformity of metal, reduce its mechanical properties and corrosion resistance. 2 铝合金材料的焊接难点2 welding difficulty of aluminium alloy materials (1)极易氧化。在空气中,铝容易同氧化合,生成致密的三氧化

3、二铝薄膜(厚度约0.1-0.2m),熔点高(约2050),远远超过铝及铝合金的熔点(约600左右)。氧化铝的密度3.95-4.10g/cm3,约为铝的1.4倍,氧化铝薄膜的表面易吸附水分,焊接时,它阻碍基本金属的熔合,极易形成气孔、夹渣、未熔合等缺陷,引起焊缝性能下降。(1) easy to oxidation. Easily with oxygen in air, aluminum, generate dense 3 oxidation 2 aluminium film (thickness of about 0.1 to 0.2 mu m), high melting point (205

4、0 ), well above the melting point of aluminum, aluminum alloy (about 600 or so). Alumina density of 3.95 4.10 g/cm3, which is about 1.4 times of aluminum, and alumina film on the surface of easy absorption moisture, welding, it's basic way of metal fusion, easily forming defects such as pores, s

5、lag inclusion, incomplete fusion, cause the weld performance degradation. (2)易产生气孔。铝和铝合金焊接时产生气孔的主要原因是氢,由于液态铝可溶解大量的氢,而固态铝几乎不溶解氢,因此当熔池温度快速冷却与凝固时,氢来不及逸出,容易在焊缝中聚集形成气孔。氢气孔目前难于完全避免,氢的来源很多,有电弧焊气氛中的氢,铝板、焊丝表面吸附空气中的水分等。实践证明,即使氩气按gb/t4842标准要求,纯度达到99.99% 以上,但当水分含量达到20ppm时,也会出现大量的致密气孔,当空气相对湿度超过80%时,焊缝就会明显出现气孔。(2

6、) easy to produce porosity. Aluminum and aluminum alloy welding porosity is the main reason of the hydrogen are produced when, because a lot of liquid aluminum can be dissolved hydrogen, hydrogen and almost insoluble solid aluminium, so when the temperature of the molten pool is quickly cooled and s

7、olidified, the hydrogen doesn't escape, easy aggregation formation porosity in the weld. Hydrogen hydrogen hole is difficult to completely avoid, the source of many, there arc welding the hydrogen in the atmosphere, aluminum plate, wire surface adsorption of moisture in the air. Practice has pro

8、ved that even if the argon gas according to standard gb/t4842 requirements, the purity of 99.99% or more, but when the moisture content of up to 20 parts per million (PPM), also can appear a large number of the density of the stomata, when the air relative humidity over 80%, porosity is apparent in

9、the weld will be. (3)焊缝变形和形成裂纹倾向大。铝的线膨胀系数和结晶收缩率约比钢大两倍,易产生较大的焊接变形的内应力,对刚性较大的结构将促使热裂纹的产生。(3) the weld deformation and crack formation tend to be large. Linear expansion coefficient of aluminium and crystallization shrinkage rate of about two times greater than steel, easy to produce the internal stres

10、s of large welding deformation, structure of rigid larger will lead to hot cracks. (4)铝的导热系数大(纯铝0.538卡/cm.s. )。约为钢的4倍,因此,焊接铝和铝合金时,比焊钢要消耗更多的热量。(4) the coefficient of thermal conductivity of aluminum big (0.538 pure aluminum card/cm. S. ). Is about four times that of steel, therefore, when the welding

11、 aluminum and aluminum alloy, burn more calories than steel welding. (5)合金元素的蒸发的烧损。铝合金中含有低沸点的元素(如镁、锌、锰等),在高温电弧作用下,极易蒸发烧损,从而改变焊缝金属的化学成分,使焊缝性能下降。(5) the evaporation loss of alloy elements. Aluminum alloy containing low boiling point elements (such as magnesium, zinc, manganese, etc.), under the action

12、 of arc in the high temperature, extremely easy evaporation loss, so as to change the chemical composition of weld metal, make the weld performance degradation. (6)高温强度和塑性低。高温时铝的强度和塑性很低,破坏了焊缝金属的成形,有时还容易造成焊缝金属塌落和焊穿现象。(6) high temperature strength and low plasticity. High temperature is very low when

13、the strength of the aluminum and plastic, destroyed the forming of weld metal, sometimes easy to cause weld metal cave and welding wear phenomenon. (7)无色彩变化。铝及铝合金从固态转为液态时,无明显的颜色变化,使操作者难以掌握加热温度。(7) no color change. Aluminium and aluminium alloy from solid to liquid, no obvious color change, make the

14、operator is difficult to control the heating temperature. 3 铝合金材料焊接的工艺方法3 aluminum material welding process (1)焊前准备(1) welding preparation 采用化学或机械方法,严格清理焊缝坡口两侧的表面氧化膜。Use chemical or mechanical method, the strict cleaning weld groove on both sides of the surface oxide film. 化学清洗是使用碱或酸清洗工件表面,该法既可去除氧化膜

15、,还可除油污,具体工艺过程如下:体积分数为6%10%的氢氧化钠溶液,在70左右浸泡0.5min水洗体积分数为15%的硝酸在常温下浸泡1min进行中和处理水洗温水洗干燥。洗好后的铝合金表面为无光泽的银白色。Chemical cleaning is the use of alkali or acid wash surface of workpiece, the method can remove the oxide film, still can be in addition to oil, specific process is as follows: volume fraction is 6%

16、 10% sodium hydroxide solution, at about 70 for 0.5 min - water - volume fraction of 15% nitric acid for 1 min at room temperature and processing - water to warm water to wash, dry. Wash the aluminum alloy surface of the matte silver. 机械清理可采用风动或电动铣刀,还可采用刮刀、锉刀等工具,对于较薄的氧化膜也可用0.25mm的铜丝刷打磨清除氧化膜。Mechanic

17、al cleaning can adopt pneumatic or electric cutter, still can use the tools, such as knife, file for thin oxide film can also be used 0.25 mm copper wire brush grinding to remove oxide film. 清理好后立即施焊,如果放置时间超过4h,应重新清理。Clean up immediately after welding, if placed more than 4 h, should be clean again.

18、 (2)确定装配间隙及定位焊间距(2) determine the assembly gap and tack welding spacing 施焊过程中,铝板受热膨胀,致使焊缝坡口间隙减少,焊前装配间隙如果留得太小,焊接过程中就会引起两板的坡口重叠,增加焊后板面不平度和变形量;相反,装配间隙过大,则施焊困难,并有烧穿的可能。合适的定位焊间距能保证所需的定位焊间隙,因此,选择合适喷灌设备的装配间隙及定位焊间距,是减少变形的一项有效措施。根据经验,不同板厚对接缝较合理的装配工艺参数如表2。Process of welding, aluminum plate thermal expansion,

19、weld groove gap decreases, welding assembly clearance before if is too small to stay, the welding process can cause two plate groove overlap, increasing surface roughness and deformation after welding; Instead, assembly gap is too big, the welding is difficult, and has the potential to burn through.

20、 Proper positioning can guarantee the required positioning welding gap, welding spacing, therefore, choose the appropriate assembly gap and tack welding spacing, is an effective way to reduce deformation. According to experience, different thickness of seam more reasonable assembly process parameter

21、s such as table 2. (3)选择焊接设备(3) the choice of welding equipment 目前市场上焊接产品种类较多,一般情况下宜采用交流钨极氩弧焊(即tig焊)。它是在氩气的保护下,利用钨电极与工件问产生的电弧热熔化母材和填充焊丝的一种焊接方法。该焊机工作时,由于交流电流的极性是在周期性的变换,在每个周期里半波为直流正接,半波为直流反接。正接的半波期间钨极可以发射足够的电子汽车衡电子而又不致于过热,有利于电弧的稳定。反接的半波期间工件表面生成的氧化膜很容易被清理掉而获得表面光亮美观、成形良好的焊缝。Welding products on the mark

22、et at present is more, general appropriate USES ac tungsten electrode argon arc welding (tig welding). It is under the protection of argon gas, the use of tungsten electrode and the workpiece asked the arc heat to melt the base and filler wire welding method. The welding machine work, due to the pol

23、arity of the alternating current is in cyclical transformation, half wave in each cycle for dc is pick up, half wave for dc reverse connection. Is answered the tungsten electrode can launch enough during the period of half wave electronic but not overheating, conducive to the stability of the arc. T

24、he reverse of the workpiece surface is generated during the period of half wave surface oxidation film is easy to clean up and get bright beautiful, forming a good weld. (4)选择焊丝(4) select wire 一般选用301纯铝焊丝及311铝硅焊丝。Generally choose 301 pure aluminium welding wire and aluminum silicon wire (311). (5)选取焊接方法和参数(5) choosing welding method and parameters 一般以左焊法进行,焊炬和工件成60°角。焊接厚度15mm以上时,以右焊法进行,焊炬和工件成90°角。General with left weldi