Do you know the development of cold-rolled automotive sheets?

1. Cold-rolled automotive sheets are developing towards ultra-deep drawing

Generally, stamped steel for automobiles is divided into three generations of products. Boiled steel is the first generation, produced and widely used in the 1950s and 1960s; aluminum-killed steel is the second generation, produced and widely used in the 1960s and 1980s; no gap Atomic steel (IF steel) is the third generation, produced and widely used after the 1980s. Interstitial-free steel (IF steel) is the stamping steel with the best deep drawability and is also the development direction of deep drawing steel in the future. Currently it is mainly used for the production of automotive ultra-deep drawing grade (EDDQ) and special ultra-deep drawing grade (S-EDDQ) stamping parts (car covering parts). In foreign countries, especially Japan and South Korea, IF steel has been widely used to replace low-carbon aluminum-killed steel in the automobile manufacturing industry. From 1986 to 1990, the world's IF steel production increased five times to 7 million tons, with Japan and Germany growing the fastest. Japan's production increased 11 times from 1986 to 1989. In 1997, the annual output of IF steel in Japan alone exceeded 10 million tons. my country's development of IF steel began in 1989. In 1995, Baosteel's IF steel output was more than 60,000 tons. In 2002, Baosteel's IF steel smelting volume exceeded 1 million tons, achieving a scale breakthrough. Deep-drawing hot-dip galvanized IF steel plates, deep-drawing high-strength bake-hardened plates and other series developed based on IF steel have formed the third generation of automotive stamping steel plates. The production of IF steel has become a symbol of a country's automotive steel plates. Reducing production costs and further improving product grade is the current direction of IF steel production and research.

2. Cold-rolled automotive sheets are developing towards ultra-high strength In order to meet the needs of "weight reduction and energy saving" of automobiles, automobile parts are increasingly made of high-strength steel plates. The application proportion of cold-rolled automotive sheets is increasing day by day, and the strength level is also gradually improving. The grades of high-strength steel plates used by various automobile manufacturers in Japan, the United States, and Europe are different, but the general trend is that the strength grade of automobile steel plates, especially plates for automobile reinforcements, is further improving. The use of high-strength steel plates is increasing in the United States and Europe, with strength grades up to 440MPa, and higher grades are being developed. The use of high-strength steel plates in Japan is increasing the fastest. Seven years ago, the rate of high-strength steel plates used in cars reached 30% to 40%, and the rate used in trucks was 5% to 10%. The strength level is also the highest. Ultra-high-strength steel plates above 980MPa are even used as reinforcement plates and bumpers for car doors. Some manufacturers have been able to produce 1470MPa-grade ultra-high-strength steel plates. Ultra-high-strength steel plates are thicker and narrower in width and are used less in automobiles, but they have certain development prospects and reflect a country's steel production technology level. With the gradual solution of the contradiction between high strength and formability, the contradiction between strip thickness reduction and corrosion resistance, welding performance, scratches, wear, chipping, fatigue and other aspects, the application of cold-rolled high-strength steel plates will become more and more widespread.

3. Cold-rolled automobile sheets are developing toward coating. As the requirements for automobile life and corrosion resistance continue to increase, the proportion of coated steel sheets 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.

4. Cold-rolled automotive sheets are developing towards special sheets

Vibration-damping steel plates were invented in the United States in the 1970s and began to be put into practical research in the 1980s. In recent years, Japan has standardized the research and production of vibration-damping steel plates. The research, development and application of vibration-damping steel plates in my country have also developed rapidly in recent years. At present, the vibration-damping steel plate production line developed and designed by Baosteel has reached scale production, and its products have been successfully used in the automotive field. The automotive industry has increasingly higher requirements for the surface quality of steel plates. Currently, in the production of cars, the amount of O5 grade plates with no surface defects used accounts for more than 30% of the total use of cold plates. How to improve production technology equipment and processes to meet the requirements for producing high-surface quality cold-rolled plates is an important topic for future production research by cold-rolled plate manufacturers.