What are the main characteristics of stainless steel?
Usage of different welding performance requirements also vary. A class of cutlery on the welding performance in general is not required, even including some pot enterprises. But the vast majority of products are required welding materials properties, like second-class cutlery, mug, steel pipes, water heaters, drinking fountains.
The vast majority of stainless steel products require good corrosion resistance, like a second class tableware, kitchen utensils, water heaters, drinking fountains, and some foreign businessmen corrosion products also do test: NACL solution heated to boiling, pour some time after out of solution, wash and drying, said weight loss, to determine the degree of corrosion (Note: When polishing products, emery cloth or sandpaper because the ingredients contained Fe, will lead to the surface rust test)
Today’s society is generally in the production of stainless steel products are polished this process, only a few products such as water heaters, drinking fountains, interior, etc. do not need polishing. Therefore, the performance of which requires a good polishing materials. Factors affecting the performance of polishing the following main points:
① material 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) when polished, and the hardness is too low, in the deep drawing surface prone to orange peel, thus affecting BQ sex. BQ relatively high hardness like.
③ after deep drawing products, deformation of the surface area will be a great little black spots and RIDGING, thus affecting BQ sex.
Refers to a high temperature heat resistance stainless steel can maintain its excellent physical and mechanical properties.
The impact of carbon: carbon in austenitic stainless steel is strong and stable formation. Given austenite and the austenite region of the expansion element. Carbon formation of austenite capacity of about 30 times that of nickel, carbon is an interstitial element, 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 steels, 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 450 ~ 850 ℃ heating), the carbon steel may Cr23C6 type carbon chromium compounds leading to the formation of a local high chromium chromium depleted, especially the corrosion resistance of the steel is decreased resistance to intergranular corrosion. As such. Chromium-nickel austenitic stainless steel is mostly carbon content of new developments since the 1960s, less than 0.03% or 0.02% ultra-low carbon type, you can know with lower carbon content, intergranular corrosion susceptibility of steel decreases, when the carbon content of less than 0.02% that has the most significant effect, some experimental pearl also noted that carbon will increase the tendency of pitting points chromium austenitic stainless steel. Due to the harmful effects of carbon, not only in austenitic stainless steel smelting control over, and in accordance with the requirements as low carbon content, and in the subsequent heat, cold and heat treatment process also prevents the stainless steel surface by carbon and chromium-free carbide precipitation.
When the number of atoms of chromium content in the steel of not less than 12.5%, the electrode potential of steel can be mutated by the negative potential to rise to the positive electrode potential. Prevent galvanic corrosion.