301L stainless steel has metastable characteristics, not only high yield strength, but also because plastic deformation can induce martensitic strengthening phase and strong work hardening ability. Compared with the previous stainless steel, the content of carbon element is reduced and hydrogen element is increased. The addition of hydrogen can eliminate the intergranular corrosion of stainless steel welding parts. The chemical composition C, N and Ni content of the plate, as well as the cold rolling deformation determine the strength level and mechanical properties of the 301L stainless steel cold rolled plate. C, N and Ni are stable austenite elements, the lower the content, the lower the stability of austenite; the greater the cold rolling deformation of the plate, the more deformation-induced martensitic phase transformation, and the stronger the work hardening effect Column, the corresponding plate strength grade is higher. Due to the difference in the amount of cold-rolled deformation and martensite transformation, the strength and plasticity of cold-rolled sheets are also different, the Japanese standard system distinguishes grades according to strength grades.
China's austenitic 301L stainless steel cold-rolled plate for vehicles is developed with reference to Japanese standards. At present, the Japanese JIS G 4305 cold-rolled stainless steel technical standard is used as a reference. 301L stainless steel cold-rolled plates include 301L-LT, 301L-DLT, and 301L -ST, 301L-MT, 301L-HT and other 5 strength grades, the yield strength of the highest strength grade is as high as 700MPa or more, surpassing any other non-heat-treated high-strength plates. Let's take a look at the comparison of five different strengths of 301L stainless steel:
301L-LT mechanical properties: the applicable cold working method has low strength, good flatness and high elongation after rolling.
Applicable welding methods: arc welding heating has no effect on its mechanical properties, so spot welding and arc welding are both acceptable.
Applicable cold working methods: Stamping, stretch bending, and bending processing for parts that do not require high strength.
301L-DLT mechanical properties: low strength, the secondary rolling rate is controlled within the range of 3% to 8%, the residual stress is small, the creep at room temperature is small, and good surface flatness can be maintained.
Applicable welding method: arc welding heating does not have much influence on its mechanical properties, so spot welding and arc welding are both acceptable.
The cold working method used: bending and drawing forming of parts with low strength, especially the processing without calendering by tempering machine.
301L-ST mechanical properties: moderate strength, the secondary rolling rate is controlled within the range of 6% to 12%, and the surface flatness after rolling is good.
Applicable welding methods: The strength of the material does not decrease significantly after heating, so spot welding is the main method, and arc welding can be used.
Applicable cold working method: It is suitable for stretch bending or bending processing of components with high strength requirements and then stretch bending processing.
301L-MT mechanical properties: the secondary rolling rate is controlled within the range of 9% to 17%, the strength is higher, but the elongation is very low.
Applicable welding method: the strength drops obviously after being heated, try to avoid using arc welding and use spot welding.
Applicable cold processing method: suitable for bending and rolling processing of long parts such as complex cross-section plates that require high strength.
Mechanical properties of 301L-HT: The secondary rolling rate is controlled within the range of 20% to 23%, with the highest strength but the lowest elongation.
Applicable welding method: the strength suddenly drops after being heated, try to avoid using arc welding and use spot welding.
Applicable cold processing method: suitable for cold bending process of high-strength and complex cross-section beam-type full-length parts.
