What are the performance advantages of stainless steel applications in car bodies?

Because the vehicle body made of lightweight materials can effectively reduce vehicle maintenance costs and save energy, vehicles using stainless steel bodies have been favored by many manufacturers. With the rapid increase in market demand for domestic subway B-type cars and the mature development of stainless steel car body manufacturing processes, lightweight stainless steel application car bodies have been rapidly adopted in large numbers.

Manufacturing lightweight stainless steel application car bodies requires the use of vehicle-specific stainless steel materials, usually 301L and 304 stainless steel. Since the content of nickel and chromium elements in 301L is lower than that of 304 stainless steel, its yield limit ratio, that is, yield strength/tensile strength, is also less than 0.8, so the stamping performance is better than that of 301L stainless steel. As for the car body strength that people are worried about, In fact, the tensile strength of the car body can also be improved through cold stamping, so don’t worry.

Because the railway vehicle body is exposed to strong vibrations, external climate conditions, and large and unstable passenger loads for a long time during operation, the overall structural form, performance, and technical level indicators of the vehicle body are mainly affected by the materials used in the vehicle body.

When designing a railway vehicle body, the basic requirements for the materials used in the body components and interior decoration are: they should have the high strength and rigidity required by the components, light weight, resistance to aging, pollution resistance, wear resistance and light resistance, etc. , suitable for environmental improvement (heat insulation, sound insulation performance improvement, better lighting), suitable for increasing comfort (vibration reduction, etc.).

Stainless steel applications for vehicles have relatively low thermal conductivity and relatively high thermal expansion coefficient. The heat conduction efficiency of austenitic stainless steel is only about one-third that of stainless steel, so the heat generated by welding can not only be dispersed very quickly, but also a lot of heat is concentrated in the weld area, and the austenite structure in stainless steel also has High instability. At 500°C to 800°C, chromium carbides in stainless steel materials will precipitate along the grain boundaries, resulting in grain boundary corrosion near the stainless steel grain boundaries due to the reduction in chromium content, and the yield strength is similar to Tensile strength also decreases rapidly.

In addition, the thermal expansion coefficient of stainless steel is about 1.5 times that of stainless steel, resulting in the deformation of the same heat being much greater than that of ordinary stainless steel. Therefore, arc full welding is usually not used in the stainless steel car body manufacturing process, and resistance spot welding is basically used. The specific resistance of stainless steel materials used in vehicles is about 6 times that of carbon steel, and is generally non-magnetic.