Composite plate problem?
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There is a device with an inner diameter of 5600 mm, made of composite steel plates of Q345R+S30403; the thickness of the end caps is 28+3 mm. The media used are cyclohexene, cyclohexanol, water, and hydrated catalysts. The operating temperature is 127°C, while the design temperature is 180°C. It is required that the composite material and its welded joints be subjected to intergranular corrosion susceptibility tests in accordance with the method specified in GB/T4334-2008, namely the \"Test Method for Corrosion of Stainless Steel in Sulfuric Acid-Copper Sulfate Medium\". The acceptance criterion is that no intergranular corrosion cracks should appear on the surface of the specimens (including the welded joints) after the bending test. No post-weld heat treatment is required for this equipment. I would like to ask fellow netizens: Should the head be formed by spinning? Hot pressing definitely won’t work. Also, for the intergranular corrosion test, is it likely to pass? Which netizen’s company has produced similar products? Please share your manufacturing experience.
GB/T 150.4,8.1.1, e): Spin-formed EHA (B) heads, subjected to heat treatment (amendment). Therefore, it is recommended to use all stainless steel for the end caps
For the heads of composite steel plates, spinning formation should be avoided as much as possible, especially cold spinning, as delamination and cracks can occur. It is recommended to consider hot stamping or segmented cold forming; by controlling the forming temperature and cooling rate properly in hot stamping, it should be possible to pass the intergranular corrosion test.
Could you send a copy of the amendment? Thank you
Apart from the hydrated catalyst, which it’s not clear what it is, the other media do not show any tendency to intergranular corrosion. The end caps are still formed by hot pressing, or by segmented hot pressing followed by welding.
Strength and corrosion requirements – strength and safety come first!
The sensitization range for stainless steel is 400°C to 850°C. How should the temperature be controlled? Can the carbon steel portion withstand sudden temperature changes?
I just consulted the head manufacturing factory, and there are two methods for forming this type of head: 1. Spin forming. 2. Formed by segmented stamping, followed by welding
Spin welding the head of a composite panel is definitely not suitable; delamination would cause problems. The stamping process is employed.
This post was last edited by INJQZ on 2019-3-6 at 15:07. For GB/T 150, fully formed EHA end caps will definitely exhibit a bilateral deformation rate that exceeds the requirements specified in Table 4. According to GB/T25198, 6.4.5.1, heat treatment is carried out after cold forming
I consulted a head manufacturing factory, and there are two methods for forming the heads: 1. Spin forming. 2. Form into segments before welding