The necessity of austenitic stainless steel pickling passivation treatment

Austenitic stainless steel has good corrosion resistance, high temperature oxidation resistance, good low temperature performance and excellent mechanical and processing properties. So it is widely used in chemical, petroleum, power, nuclear, aerospace, Marine, pharmaceutical, light industry, textile and other departments. The main purpose is to against corrosion. The corrosion resistance of stainless steel relies mainly on the surface passivation membrane, if the film is incomplete or flawed, and stainless steel will corrode. Engineering are usually for pickling passivation treatment, make the corrosion potential of stainless steel to the greater. In a stainless steel equipment and parts in the molding, assembly, welding, weld inspection ( Such as inspection, pressure test) In the process of its construction and tag with surface oil, rust, dirt non-metallic, low melting point metal pollutants, paint, welding slag and splash content etc, these substances affect the surface quality of stainless steel equipment and parts, destroyed the surface oxide film and reduce the general corrosion resistance and resistance to local corrosion of steel performance ( Including pitting, crevice corrosion) And even lead to stress corrosion cracking. Stainless steel surface cleaning, acid pickling and passivation, in addition to the utmost to improve the corrosion resistance, and to prevent product contamination and aesthetic effect. In GBl50 1998 'steel pressure vessel' regulation, 'there is a requirement for anti-corrosion stainless steel and the surface of the container of the composite plate manufacture should be pickling passivation'. This rule is for use in petroleum chemical industry, pressure vessel, because the equipment is used for direct contact with the corrosive medium phase, starting from guarantee corrosion resistant corrosion resistance, acid pickling passivation is necessary. For other industrial sectors, such as not for anti-corrosion purpose, only based on the requirement of clean and beautiful, and adopt stainless steel material is no need for pickling passivation. But for the weld of the stainless steel equipment for pickling passivation is needed. Use of nuclear engineering, some chemical plant and other requirements strictly, in addition to the pickling passivation, but also with high purity fine for a final cleaning or mechanical, chemical and electrolytic polishing finishing processing.