â‘´ Preheat conducive to reduce the maximum hardness of the heat affected zone of medium carbon steel, to prevent the generation of cold cracking, which is the main process for Stainless Steel Welding Electrodes, preheating can also improve the fitting plastic, to reduce the residual stresses after welding. Generally, the preheating temperature was 150 ~ 250 â„ƒ then high carbon content, or due to the thickness and stiffness, a tendency to crack when the preheating temperature was raised to 250 to 400 ° C for 35 and 45 steel.
The weldment too the overall preheat difficult, local preheating, heating range of local preheating of weld on each side 150 ~~ 200mm.
â‘µ preferred basic electrode welding rod when conditions permit.
â‘¶ groove forms will try to open the weldment into a U-shaped groove for Welding Wires If casting defects, dig out the bevel shape should be smooth, and its purpose is to reduce the base material is melted into the ratio of the weld metal, in order to reduce the carbon content in the weld and to prevent cracks.
â‘· welding parameters Since the base material is melted to the melting of the first layer of weld metal in the proportion of up to about 30%, so the first layer weld, should be adopted when the small current, slow welding speed, to reduce the base material deep.
Best weldments Claim â‘¸ post-weld heat treatment after welding stress relief heat treatment, especially for large thickness of the weldment, the high-rigidity structure member, and under stringent conditions (dynamic load or impact load) weldment more so. Stress relief tempering temperature of 600 ~ 650 â„ƒ.
Can not be post-weld stress relief heat treatment should be carried out immediately after the heat treatment.
Stainless steel is greater than 12% of chromium-containing steels. Stainless steel made rapid development since the 1912 invention, since the world is still an annual increase rate of 3-5%. Stainless steel consumption worldwide total of 35 million. China is in a period of rapid growth for stainless steel production and consumer applications, has been widely used in the petroleum, chemical industry, light industry, food, brewing, pharmaceutical, household appliances, water, electricity, machinery, construction, municipal and various civilian appliances. China's stainless steel consumption in 1990 to 26 million tons in 1999 to 1.53 million tons, 1.73 million tons in 2000, 225 million tons in 2001, the consumption of stainless steel in 2004 reached 4.47 million tons, ranking the world's first Stainless steel consumption in 2006 is expected to reach more than 6 million tons, consumption accounts for the total consumption of stainless steel, chrome-nickel austenitic stainless steel 75% -80%.
China from the fifties to the development and production of stainless steel electrode, 1997 the total output of China's stainless steel electrode for more than 7000 tons. Consumption of stainless steel in China in recent years, the rapid growth of the domestic stainless steel electrode has more than 35 thousand tons in 2004, the 2006 domestic stainless steel electrode is expected to reach about 50,000 tons.
Stainless steel Welding Electrode developed since the fifties followed the former Soviet Union calcium titanium slag system and raw materials system, it has the advantages of low cost, easy pressure coated, anti stomatal good, good mechanical properties, but similar to the European brand stainless steel electrode Compared redness serious welding rod, big splash off slag and forming, welding and low efficiency, wastage, therefore, since the mid-seventies to the early eighties, Sweden AVESTA green P5 electrode domestic imports for domestic research institutions electrode production enterprises cooperate on stainless steel electrode covering redness off and the solution to the research, such as Kazakhstan welding Welding Electrode Factory and Tianjin, Gansu workers with Lan Chau Changhong welding electrodes, Taiyuan University of Technology, Shanxi Machine Tool Plant and so on.
To the 1980s, the above several papers have been published, the one hand, people think that their work makes sense to get a lot of progress; On the other hand, after electrode actual test of these several developed that foreign products still significant gaps, but since then, the research work in this regard to the situation in anything less from the early 1980s to the decade of the nineties, within no weight stainless steel electrode research literature. From the early 1990s, the domestic stainless steel electrode research is becoming more active. First, the basic principles and ways of stainless steel electrode process design, Taiyuan industrial magnate Bao, Sun salty et al studied on the basis of the preliminary work has made an important breakthrough in the stainless steel electrode design theory, and won the 2000 National Science and Technology Progress Award ; after Tang Bo Steel, Building Research Institute of the Ministry of Metallurgical Industry, digestion and absorption of foreign advanced technology in the mid-nineties, the successful completion of a series of new domestic stainless steel electrode improvement to improve, and successfully set up Beijing Jinwei Welding Materials Co., do the theory and practice the perfect combination of production since its beginning in 1994 to the present, its Stainless Steel Welding Rodproduction has reached an annual output of more than 3,000 tons.
The late nineties to the early part of this century, the domestics tainless steel electrode study, carried out mushroomed, although itself does not exceed the level of the two existing levels, but still have the benefits of active academic atmosphere and strengthen the exchange of learning.