Penetrating cracks were found in the head straight section of a stainless steel tank before it was put into use. Penetrant testing, chemical analysis, metallographic analysis, X-ray residual stress test, crack surface scanning electron microscopy analysis and energy spectrum analysis was applied to study the cause of the cracks. The results showed that, chloride ion stress corrosion cracking was the reason of the failure. Metal magnetic memory detection and hardness testing were also used to evaluate the stress distribution of the head. The extreme points of the magnetic field gradient, hardness and tensile stress showed high coherence to the positions of the cracks. These results indicated that the metal magnetic memory method has good application prospects for the assessment of stainless steel deformation and stress state.

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