Austenitic stainless steel has a larger linear expansion coefficient

       Austenitic stainless steel has a larger linear expansion coefficient

The austenitic stainless steel used in thermal spraying is mainly 18-8 nickel-chromium stainless steel (also known as SUS304). Its carbon content is low, generally between 0.05% and 0.12%. Sometimes, in order to improve the corrosion resistance, it is also added A small amount of Mo prevents intergranular corrosion by adding a small amount of Ti or Nb (such as SUS321 or 347).







 The austenitic stainless steel coating is an austenitic structure at room temperature. It has excellent corrosion resistance, heat resistance, good wear resistance and good processing performance, and it is not magnetic.







It is mainly used for wear parts that work in most acid and alkali environments and has good processing performance. It is not magnetic. Mainly used for the protection and repair of wear parts that work in most acid and alkali environments, such as spray water pump shafts, paper dryers, etc.







However, the coating shrinkage rate is large, so it is suitable for spraying a thinner coating, otherwise it is prone to cracking and peeling. It should be noted that when applying austenitic stainless steel coating, the coating must be properly sealed, because the austenitic stainless steel coating is a cathode for the steel substrate. Once the coating is damaged, the steel substrate will accelerate corrosion.







At present, there is no wire rod specially produced for arc spraying in China, and only suitable wire rods can be selected from the existing welding materials for arc spraying.







Commonly used grades of wire include 1Cr18Ni9Ti, 1Cr18Ni9, 0Cr18Ni9, 1Cr18Ni9Mo2, etc. These materials have good wear resistance, strength, and corrosion resistance, and the coating has a large shrinkage coefficient and low hardness.







However, attention should be paid when spraying this type of stainless steel with a large linear expansion coefficient. Ferritic stainless steel Ferritic stainless steel contains 15% to 30% chromium, and Cr8 is a typical steel grade. It is a ferrite structure at room temperature, and it has good corrosion resistance.







In order to improve the corrosion resistance, pitting corrosion resistance and stress corrosion cracking performance, the austenitic-ferritic composite steel has been developed.