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摘要本文针对某厂汽车前门铰链加强镀锌板与螺纹镀锌板使用熔化极气体保护焊进行搭接焊，由于该汽车配件批量大，生产节奏快，被焊零件不仅镀锌，表面还有少量润滑油，焊接中焊缝起弧和收弧处经常出现气孔，不能满足该车的质量要求。通过大量的试验，得出了合理的焊接工艺参数。SAF焊机焊接试验表明：当焊接电流为122A，焊接电压为24V，送丝速度为5.0m/min，焊接速度为40cm/min时，焊缝成形良好，表面光滑，无裂纹气孔等缺陷。FRONIUS焊机焊接试验表明：当焊接电流为140A，焊接电压为23V，送丝速度为6.5m/min，焊接速度为35cm/min时，焊缝成形良好，表面光滑，无裂纹气孔等缺陷。23417
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宏观缺陷观察显示：在焊缝的起弧处和熄弧处容易产生气孔，由于配件表面油的存在导致焊接过程中容易产生气孔，起弧时焊接的热输入不足熔池存在时间短气体未完全溢出容易产生气孔；熄弧时冷却速度快，熔池存在时间短气体未及时溢出易产生气孔。
金相试验观察显示：焊缝为明显的柱状晶，主要为珠光体+铁素体，热影响区为粗大的珠光体+铁素体，2mm的前门铰链加强板比4mm的螺纹板晶粒要粗大。
毕业论文关键词： 镀锌钢板，工艺参数，气孔，组织分析
毕业设计说明书（论文）外文摘要
Title Experimental study on gas shielded welding galvanized steel melting
Abstract
Aiming to strengthen the former factory car door hinge with threaded galvanized sheet galvanized sheet using MIG welding performed lap welding, auto parts due to the large volume, fast-paced production, not only galvanized welded parts, as well as a small amount of lubricating surface oil, welding and arc welding arc at the closing holes often can not meet the quality requirements of the car. Through a lot of tests, obtained reasonable welding process parameters. SAF welder tests showed: when the welding current is 122A, welding voltage of 24V, wire feed speed is 5.0m/min, welding speed 40cm/min when the weld is good, smooth surface, no cracks holes and other defects. FRONIUS welder tests showed: when the welding current is 140A, welding voltage of 23V, wire feed speed is 6.5m/min, welding speed 35cm/min when the weld is good, smooth surface, no cracks holes and other defects.
Macroscopic defects observed Show: The arc of the arc at the weld and prone to porosity, surface fitting due to the presence of oil led to the welding process prone to porosity, arc welding heat input less than the existence of a short time the pool is not completely gas overflow prone pores; when extinction cooling speed, the pool did not exist a short time gas is easy to produce timely overflow vent.
Metallurgical test observations show: Weld obvious columnar crystals, mainly of pearlite and ferrite, the heat-affected zone of coarse pearlite and ferrite, front door hinge stiffener than 2mm to 4mm thread board grains thick.
Keywords：galvanized steel, process parameters, porosity, organizational analysis
目录
1 绪论 1
1.1 选题的目的及意义1
1.2 镀锌钢板在国内外的研究现状2
1.3 镀锌钢板现有的焊接方法3
1.1.1 镀锌钢板的电阻点焊4
1.1.2 镀锌钢板的电阻凸焊4
1.1.3 镀锌钢板的CO2激光焊 4
1.1.4 镀锌钢板的脉冲电弧钎焊5
1.1.5 镀锌钢板的熔化极气体保护焊5
1.4 本课题要研究的主要内容5
2 实验设备、所需材料及方法 7