What should be done when the performance of 304L stainless steel cold-rolled sheet is impaired

304L stainless steel cold-rolled sheet is transformed into stainless steel products through various processing techniques and then applied to various industries. But do you know how to solve the problem if the performance of 304L stainless steel cold-rolled sheet is impaired?

1. The lattice dislocation or phase change of 304L stainless steel cold-rolled sheet occurs on the surface, which will become the starting point of local corrosion such as pitting. When the deformation degree reaches 20% of the cross-section rate, this phenomenon will have a direct adverse effect.

2. It will cause the increase of microscopic defects such as lattice dislocation and surface roughness of 304L stainless steel cold-rolled sheet, and induce martensitic phase transformation and carbide precipitation, such as increased magnetism after cold working.

3. After cold working, residual stress will be left in 304L stainless steel cold-rolled sheet, which is extremely unfavorable to the stress corrosion cracking resistance of 304L stainless steel cold-rolled sheet. Any degree of cold working will greatly increase its sensitivity to stress corrosion cracking.

4. The degree of cold working also hurts the high temperature endurance strength of 304L stainless steel cold rolled sheet. Generally, the higher the working temperature or the higher the fracture life requirement, the lower the allowable degree of cold working.

5. For 304L stainless steel cold rolled sheet subjected to alternating loads, cold working will hurt the increase in its crack propagation rate due to the reduction in elongation and residual elongation.

Solutions to the above problems:

1. The stainless steel standards of most countries, especially the unified stainless steel standards in Europe, stipulate that all stainless steel must be supplied in a solid solution or annealed state to eliminate the performance damage caused by cold working and welding.

2. Three key parameters should be paid attention to in solid solution treatment: heating temperature, rapid cooling method, and high temperature residence time. Excessive solid solution treatment temperature or residence time will be detrimental to the corrosion resistance of 304L stainless steel cold rolled sheet. To determine whether the solid solution treatment is in place, hardness measurement, flaring, curling, flattening, and stretching data can be determined, among which hardness measurement is relatively simple.

3. Since solution or annealing significantly increases manufacturing costs and production cycles due to high-temperature heating and pickling, and there are waste gas and wastewater emissions such as acid mist, some companies omit this process and use this product, which is prone to production and personal accidents after use.

4. For some stainless steel products or application conditions, it may be difficult to perform solution or annealing. Therefore, controlling the degree of cold working (cold working deformation) and performing local low-temperature stress relief annealing are practical methods to reduce harmful effects.