| In 2000, the apparent consumption of stainless steel in our country is about 2 million tons, and is estimated to reach 8 million tons in 2010, 4 times that of 2000. The stainless steel in industry production shows great potential to increase, and will certainly drive the growth of welding material of stainless steel.Stainless steel flux cored wire(FCW) have high efficiency of production, good quality of welding, low cost and so on, so it has been vigorously developing in recent years. However, its process of welding still have some problems, such as removability of slag, the sensitivity of porosity (press pit ) and high-temperature cracking in weld metal, which are not completely resolved. Therefore, in recent years it had was being the goal for weld workers that stainless steel FCW have good process of welding, anti-high tempeature carcking, property of all position welding be made.The welding porcessing of FCW for 308L stainless steels was studied comprehensively in the following dissertation.(1) The slag detachability of FCW for stainless steels containing A additives was studied. The experimental results showed that A species of additives had obviously effcet on FCW detachability, but it had great influence on the property of welded joints, so it need to strictly controll the content of additives A. and find a formula that have a little of A addition, but the slag detachability of FCW stainless steels was very good. And though the adoption of uniform designed, the mainly composition of powder with low A additive was profoundly studied. The experimental results showed that it can solve the slag detacbility of stainless steel flux cored wire with a little of A additive by reasonable adopting the ratio of natural rutile, quartz, fluoride, manganese.(2) The paper used Hannover Arc analyzer to quantitative analye the arc voltage, welding current of vertical welding in different of four kinds of stainless steel flux cored wire. The experimental results showed that the advantages and disadvantages of vertical welding of stainless steel FCW were able to accurately and objectively evaluate by the change of instant arc voltage and current signal, as well as the waveform of probability density distribution of the welding voltage, the welding current, class frequency distribution of the short-circuiting time and their standard deviation. It also achieved quantitative analysis and evaluation of the vertical welding process(arc staility, metal transfer, splash and so on) for FCW, and it has great practical significance for all-position flux cored wire formulation to optimize design of work.(3) The factors such as the major mineral elements of powder, the content amount of water in powder easily lead to hole pressure were studied. The experiment result showed that it could reduce the tendency of porosity(press pit) in weld metal by adjusting the content of cryolite, Al-Mg alloy, fluoride in powder and the drying process. The effect of different weld parameter conduct the tendency of porosity(press pit) in weld metal was also studied. It found that the ratio of porosity(press pit) first decreased and then increased with the increasing of welding parameters, and the ratio of porosity(press pit) first raised and the downtrend with the increasing of welding speed. |
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