焊接本科毕业设计论文.doc

摘 要
不锈钢自1912年发明以来取得迅猛发展，至今全球仍以每年3%～5%的速度递增。我国正处于不锈钢生产和应用的高速增长期，2001年我国不锈钢的使用量已跃居世界第一。不锈钢通常含有 Cr(WCr ≥ 12%)、Ni、Mn、MO等元素，具有优异的耐蚀性能以及特有的力学性能、物理性能和工艺性能使其适于制造要求耐腐蚀、抗氧化、耐高温和超低温的零部件设备，故而不锈钢具有广泛的应用前景，其焊接具有特殊性。
不锈钢在电阻点焊过程中极易产生飞溅，焊接接头处易出现结合面断裂，将直接影响焊接接头的质量。本文针对上述问题，研究了304不锈钢电阻点焊接头的组织结构特点，分析了焊接电流、焊接时间、电极压力以及焊接过程中对电阻点焊接头组织和性能的影响。实验表明：当焊接电流为6000A，电极压力为4000N，焊接时间为7个周波时焊点性能最好。接头的主要结晶形态为柱状晶，其结合面为点焊接头的薄弱区域。不锈钢点焊接头易出现裂纹及缩孔等焊接缺陷，使点焊接头质量降低。
关键词: 304不锈钢,电阻点焊,微观组织,力学性能
Abstract
Stainless steel has been developed rapidly since its invention in 1912, so far the world still with annual 3% to 5% annually. Our country is in the rapid growth of production and application of stainless steel, 2001 usage of stainless steel in China has been ranked first in the world. Stainless steel is referred to as the corrosion and heat resistant alloy steel. So usually contain Cr(WCr≥12%),Ni, Mn, Mo and other elements, with excellent corrosion resistance and mechanical properties, unique physical properties and processing properties make it suitable for manufacturing requirements of corrosion resistance, high temperature resistance and parts of equipment of ultra low temperature, and so has the widespread application prospect, the welding with special.
Stainless steel in the process of resistance spot easily to have rained down, welding joints with face easy appear rupture, will directly affect the quality of the welding joint. This is article in view of the above problems, 304 stainless steel resistance spot joint of the organizational structure characteristics, analyzed the welding current, welding time, electrode pressure and welding process of resistance spot joint organization and performance influence. The experiment showed that when welding current for welding current 6000A, electrode pressure for 4000N, welding time for 7cyc solder joint performance is the best. The main crystalline form joint is columnar crystals , which combined surface area for the weak spot we