Issues regarding the pressing of end caps and spherical shells
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I don’t understand manufacturing, so I’ll ask a rather stupid question: When manufacturing end caps, cylinders, or spherical shells, permanent deformation occurs – can the mechanical properties of the final product still match those of the original steel sheet? Especially for spherical heads, the steel plate has been significantly thinned; yield and strengthening effects should have occurred. Are the original data for the mechanical properties, allowable stress, impact resistance, etc., of the steel plate still appropriate?
Permanent deformation of steel definitely indicates a state of yield; the impact on the material’s properties increases as the degree of deformation increases. However, it doesn’t mean that deformation necessarily requires consideration of its effect on the material’s properties. GB150 stipulates that for cold-formed heads, if the degree of deformation exceeds a certain limit, heat treatment to restore their properties is required. Hot-forming of heads is carried out at the forging temperature, and it generally does not affect the mechanical properties of the material; however, this depends on the requirements for using that material. If hot-forming changes the heat treatment state required for the material, heat treatment must be performed again.
The first floor explained it in too much detail; I learned it*
Spherical heads are generally formed using melon-seed petal methods, with the thickness reduction kept within 10%.
The deformation of the steel plate does not have an impact within a certain range