316 and 316L stainless steel are molybdenum-containing stainless steel species. The molybdenum content in 316L stainless steel is slightly higher than 316 stainless steel. Because of molybdenum in the steel, the overall performance of this grade is better than 310 and 304 stainless steel, under high temperature conditions, when the concentration of sulfuric acid is lower than 15% and above 85%, 316 stainless steel has a wide range of uses. 316 stainless steel also has good chloride corrosion performance, so it is usually used in marine environment. 316L stainless Steel maximum carbon content of 0.03, can be used for welding can not be annealed and the need for maximum corrosion resistance of the use.
316 stainless steel corrosion resistance is superior to 304 stainless steel, in the pulp and paper production process has good corrosion resistance performance. and 316 stainless steel is also resistant to the erosion of the marine and corrosive industrial atmosphere.
Generally speaking, 304 stainless steel and 316 stainless steel in the chemical corrosion resistance of the difference is not, but in some specific medium there are differences.
The first developed stainless steel is 304, which is sensitive to pitting corrosion (pitting corrosion) in specific cases. An additional 2-3% of molybdenum can reduce this sensitivity, and this is the birth of 316. In addition, these additional molybdenum can also reduce the corrosion of some hot organic acids.
316 stainless steel has almost become the food and beverage industry standard materials. Because of the worldwide shortage of molybdenum and 316 stainless steel nickel content more, 316 stainless steel price than 304 stainless steel more expensive.
Pitting corrosion is a phenomenon mainly caused by the deposition of stainless steel surface, which is due to hypoxia and cannot form a protective layer of chromium oxide.
Especially in small valves, the possibility of deposition on the valve plate is very small, so pitting corrosion is rarely occurred.
In various types of water medium (distilled, drinking water, water, boiler water, seawater, etc.), 304 stainless steel and 316 stainless steel corrosion resistance is almost the same, unless the content of chlorine ions in the medium is very high, at this time 316 stainless steel is more appropriate.
In most cases, 304 stainless steel and 316 stainless steel corrosion resistance is not much different, but in some cases may be very different, need specific analysis. Generally speaking, valve users should have a better idea, because they will choose the material of the container and pipe according to the condition of the media, do not recommend the material to the user.
For continuous use below 1600 degrees and 1700 degrees, 316 stainless steels have good oxidation resistance. In the range of 800-1575 degrees, it is best not to continuously function 316 stainless steel, but in the range of temperature outside the continuous use of 316 stainless steel, the stainless steel has good heat resistance. 316L Stainless steel carbide precipitation performance than 316 stainless steel better, can be used above temperature range.
Annealed at a temperature range of 1850-2050 degrees, then quickly annealed and then cooled rapidly. 316 stainless steel can not overheat treatment for hardening.
316 stainless steel has good welding performance. All standard welding methods can be used for welding. Welding can be used in accordance with the use of 316Cb, 316L or 309Cb stainless steel packing rods or welding electrodes for soldering. In order to obtain the best corrosion resistance, the welding section of 316 stainless steel has to be treated by welding back fire. If the use of 316L stainless steel, no need for welding back fire treatment.
Of all steels, the yield point of austenitic stainless steels is the lowest. Therefore, from the mechanical properties, austenitic stainless steel is not used in the valve stem of the best material, because to ensure a certain strength, stem diameter will increase. Yield points cannot be improved by heat treatment, but can be improved by cold forming.
Because of the wide application of austenitic stainless steel, it gives people the wrong impression that all stainless steel is not magnetic. For austenitic stainless steel, the basic can be understood as non-magnetic, quenched the forged steel is indeed so. But through the cold molding treatment of 304 will be a little bit of magnetism. For cast steel, if 100% austenitic stainless steel is not magnetic.
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