Stainless Steel (Stainless Steel) is referred to as acid-resistant stainless steel, resistance of air, steam, water and other weak corrosive media or of stainless steel has called stainless steel; and the resistance to chemical corrosion (acid, alkali, salt and other chemical leaching Eclipse) variants known as acid-resistant steel. As the two differences in the chemical composition of leaving their corrosion resistance is different from ordinary stainless steel resistant to chemical corrosion in general, and acid-resistant steel are generally of a stainless steel. The main characteristics of the welded products use different welding performance requirements also vary. A tableware welding performance in general is not required, even including some pot enterprises. But most products require materials welding properties, like second-class tableware, mug, steel pipes, water heaters, drinking fountains. The corrosion resistance of stainless steel products require the vast majority of good corrosion resistance, like a second class tableware, kitchen utensils, water heaters, drinking fountains, and some foreign businessmen also do corrosion product test: NACL solution was heated to boiling, a period Discard solution after time, wash drying, said weight loss, to determine the extent of corrosion (Note: When polishing products, because of emery cloth or sandpaper containing Fe component, can cause the surface rust test) stainless steel polished performance in today's society products in the production of this process is generally polished, only a few products such as food, drinking fountains interior, etc. do not need polishing. Therefore, the performance of which requires a good polishing materials. Factors affecting polishing performance are mainly the following points: ① raw materials surface defects. Such as scratches, pitting, excessive pickling. ② raw material problem. Hardness is too low, it is not easy to throw light (BQ bad) is polished, and the hardness is too low, in the deep stretch prone to orange peel surface, thus affecting BQ sexual. BQ high hardness relatively good. ③ after deep drawing of products, areas of extreme deformation of the surface will be a small black dot and RIDGING, thus affecting BQ sexual. Heat resistance refers to a high temperature stainless steel can maintain its excellent mechanical properties. Influence of carbon: carbon in austenitic stainless steels is strongly formed and stable. And expand the elements set austenite austenite region. Carbon austenite forming ability of about 30 times the nickel, carbon is an interstitial element, by solid solution strengthening can significantly improve the strength of austenitic stainless steel. Austenitic stainless steel carbon can also improve performance in high concentration of chloride (eg boiling 42% MgCl2 solution) resistance to stress corrosion. However, in austenitic stainless steel, carbon is often regarded as harmful elements, mainly due to the corrosion of the stainless steel under some conditions of use (such as by welding or by heating 450 ~ 850 ℃), with carbon steel Cr23C6 Carbon chromium compounds leading to the formation of high chromium local chromium depletion, the steel corrosion resistance particularly resistance to intergranular corrosion decline. Therefore. Chrome-nickel austenitic stainless steel carbon content of mostly new developments since the 1960s, less than 0.03%, or 0.02% of ultra-low carbon type, it is known as the carbon content is reduced, intergranular corrosion susceptibility decreases when the carbon content of less than 0.02% only with the most significant results, some experimental Pearl also noted that carbon will increase the tendency of pitting points chromium austenitic stainless steel. Because of the harmful effects of carbon, not only in the austenitic stainless steel smelting and in accordance with the requirements over control of the carbon content as low as possible, and in the subsequent heat, cold and heat treatment process also prevents the surface by carbon steel and chromium-free carbide precipitation. When the steel corrosion resistance of chromium content of not less than 12.5% ??of the number of atoms, the electrode potential of steel can be mutated by the negative potential to rise to the positive electrode potential. Prevent electrochemical corrosion.