Since the advent of the first automobile in the 1880s, the automotive industry has continuously improved and improved its requirements on the types, surface quality, mechanical properties, corrosion resistance and other requirements of the sheets used.
Especially now, with the increasing requirements for energy, safety and environmental protection, the development of automotive panels
Development and application also pose higher demands and challenges.
Quality requirements for cold-rolled automobile sheets. Generally, the automobile industry has the following requirements for the cold-rolled steel sheets used:
1) Excellent formability, namely: high plastic strain ratio r value, high uniform elongation 8u, high total elongation 8, low yield strength. Low aging index Al and low yield elongation, Used for stamping complex automotive panels.
2) Excellent dent resistance and sufficient structural rigidity to avoid dents during manufacturing and use, especially in sudden collision accidents, to maximize energy absorption and protect the safety of the occupants.
3) Good welding performance, ensuring effective connection of parts and solder joints and areas around the solder joints
There will be no major changes in strength and performance.
4) Excellent surface morphology and smoothness, good spraying performance and adhesion to paint coating, in order to achieve a beautiful surface.
5) High corrosion resistance
6) Good plate shape and surface flatness, strict dimensional accuracy and performance uniformity.
7) Good sound absorption and vibration damping properties, used in some parts to reduce the thunderous effect of the car while driving.
Due to these special quality requirements of cold-rolled automobile sheets, the production process is complex and difficult. Therefore, the manufacturers of automobile sheets have adopted the principle of consistent production in actual production, that is, smelting, continuous casting, hot rolling, cold rolling, and annealing. and coating and plating and other processes involved in unified production planning and management.
As the requirements for automobile life and corrosion resistance continue to increase, the proportion of coated steel plates used in automobiles is increasing year by year. Hot-dip galvanizing is growing faster than electro-galvanized steel sheets because the cost of hot-dip galvanized steel sheets is lower than that of electro-galvanized steel sheets. In recent years, as hot-dip galvanizing strip technology has continued to make substantial progress, the surface quality of hot-dip galvanized strip steel has continued to improve. It has gradually approached the surface quality of electro-galvanized products and partially replaced electro-galvanized products for automotive exterior cladding. In terms of automotive panels, the trend of hot-dip galvanizing replacing electro-galvanized products is increasingly obvious. With the development of my country's automobile industry, especially the improvement of automobile grades and the improvement of coating plate performance, the amount of coated plates will increase rapidly, and surface-treated steel plates will be vigorously developed. High-strength steel surface-treated steel plates combine high strength and excellent corrosion resistance. Combining these advantages will inevitably become the top priority in the development of automotive steel plates.
