Radial cracks appeared in the 31603 head during use, as shown in the picture
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Our unit produces 4 reactors. The material is 31603, medium caustic soda, isoamyl alcohol, water, working temperature 150 degrees, working pressure -0.01 to 0.15Mpa. Now one of them has the problem in the picture, there are 2 pits, and there are radial cracks after polishing and coloring inspection. What is the reason?
Material storage, processing and use are not standardized. contaminated.
Stress corrosion should be caused by halogen ions
Like what kind of pollution? We need to find the reason
How are halogen ions produced? We need to find the cause. Is it hydrogen embrittlement or alkali embrittlement caused by hydrogen white spots?
It should be alkali brittle and the temperature is a bit high.
I understand that excessive amounts of ferrite or martensite appear during the head forming process, causing cracks. Therefore, during the manufacturing process of the head, the ferrite content in the head should be strictly controlled, with no more than 5% being considered qualified, otherwise there will be trouble in future use.
Analyze the influencing factors at each stage of material selection, head processing and manufacturing, equipment assembly and welding, and production operation one by one, and investigate them one by one to find out the most likely influencing factors. Analyze, judge, and research solutions and plans. 1. Problems with the material itself 2. Quality control of head processing and manufacturing 3. Welding removal of lifting accessories during equipment assembly and welding 4. Inspection of working conditions and operations
Do metallography, hardness and pH. Alkali embrittlement cracks in 300 stainless steel are very similar to chloride ion stress corrosion cracks.