Stainless steel butterfly valves will inevitably be rusted during use. It is very important to find out what causes the corrosion of stainless steel butterfly valve. Through the material and structure analysis, heat treatment test, SEM and other tests of the butterfly valve, the plates are divided. Because the carbide precipitates along the grain boundary in the valve material to form a division zone, which is the reason for the corrosion of the stainless steel butterfly valve.
Tianjin Exxon valve introduces the following methods to solve the corrosion:
1. Test method:
Take samples for chemical composition analysis (to judge whether it meets the standard requirements), metallographic structure inspection, heat treatment process test and SEM analysis.
2. Test results and analysis
(1) Chemical composition: chemical composition analysis results and standard components.
(2) Metallographic analysis: the metallographic sample was cut from the rusted butterfly valve. After grinding and polishing, it was corroded with ferric chloride aqueous solution, and observed and analyzed on the neohot-32 metallographic microscope. The metallographic structure is composed of austenite and another precipitate. In theory, austenitic stainless steel should have homogeneous austenite structure after normal heat treatment