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What are the effects of magnetism on the performance of stainless steel strip after cold processing
source：www.cnlichao.net | Release time：2026年11月03日Beneficial:
Martensite is a hard phase, which, when combined with cold work hardening, increases tensile strength, hardness, yield strength, and elasticity. This is also the principle of 301 steel strip using large deformation to make spring plates and clamps.
Disadvantage:
The plasticity and elongation continue to decrease, and the material becomes brittle; The greater the deformation and the more martensite, the easier it is to crack during subsequent bending, deep drawing, and forming.
Material uniformity deterioration: uneven deformation → uneven distribution of martensite → inconsistent hardness and rebound at different positions of the steel strip, resulting in greater dimensional fluctuations in stamped parts.
2. Corrosion resistance performance
Reduced resistance to pitting corrosion and chloride ion corrosion: The electrode potential of α '- martensite is lower than that of austenite. In humid, salt spray, and chlorine containing environments, a micro electric couple is formed between austenite and martensite, and the martensite region is preferentially corroded.
The risk of stress corrosion increases: the coexistence of residual stress and martensite in cold processing makes stress corrosion cracking more likely to occur under chloride ion conditions (seawater, spray, chemical water vapor).
Comparison: Under the same deformation, 316L has higher molybdenum content and a much smaller corrosion resistance attenuation amplitude than 304; 201 nickel is low, martensite is abundant, and corrosion reduction will be very significant.
Attention: If it is only slightly magnetic and contains a small amount of martensite, the impact of a conventional indoor dry environment is minimal; Salt spray, humid outdoor, and seawater accessories should be evaluated with emphasis.
3. Dimensional stability and rebound
Martensitic transformation is accompanied by volume expansion (with a volume change of about 0.5%), plus residual stress:
Steel strips are prone to sickle bending, warping, and uneven surface;
After stamping and bending, the rebound amount increases and the rebound is unstable; After being stored for a period of time, there is still slow deformation (aging deformation).
4. Welding performance
When welding steel strips containing a large amount of strain martensite:
The organization of the heat affected zone is complex and more prone to welding cracks;
The cooling process after welding will continue to undergo phase transformation, resulting in uneven magnetic and hardness properties around the weld seam;
The corrosion resistance further deteriorates after welding, and post weld solution treatment may be necessary.
5. Electromagnetic related effects (for parts with electromagnetic requirements)
If the product requires a non-magnetic and low magnetic environment (instrument shielding, sensor accessories, magnetic control components): magnetism will directly cause interference and is considered unqualified;
Ordinary structural components, decorative components, and gaskets do not affect their use due to their magnetic properties, but they are easily mistaken by customers for counterfeit materials.
6. Fatigue performance
Moderate martensite can enhance fatigue strength; However, excessive martensite content and stress concentration can easily become sources of fatigue cracks, leading to a decrease in fatigue life under alternating working conditions.
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