During Flexible Thin Slab Production Line Developed High Strength Automobile Frames

In order to further broaden the scheme of Tonghua Steel FTSR production line, promote the Market competitiveness of Tonghua Steel in the Current steel market. Tonghua Steel Technology Center Cooperate with China Iron and Steel Research Institute Casting Centre Court using FTSR production line, through the chemical composition and microstructure of the FTSR optimize the design and use of their own production line equipment and technology advantages developed a high-strength beam plate for automobile.For the smooth completion of this topic and formation of industrial production, made the following main points:1. Adoption of the chemical composition and microstructure design optimization, resource conservation, energy at the same time improve the performance of the integrated plate girders;2. Beam plate slab by observing the low times, and test the macro-quality billet;3. Use Gleeble-1500 thermal simulation experiment to test the beam plate slab high-temperature mechanical properties, for the adoption of the slab temperature control parameters improve slab quality to provide reliable experimental data;4. By Gleeble-1500 thermal simulation testing machine, and the use of thermal expansion of metallographic determination and a description of the automobile beam plate CCT curve, the steel for industrial production accelerated cooling after rolling process provide experimental basis;5. TMCP by optimizing process parameters to avoid mixed grain phenomenon occurred balance test of the strength and toughness of plastic, and to identify vehicles for the production of high-intensity beam of the standards board system;6. Through stretching, low-temperature impact of a series of experimental mechanics test the mechanical properties of the steel, and using optical microscopy, scanning electron microscopy, transmission electron microscopy, and other means of testing the test of the steel microstructure and shape of inclusions appearance and size, the precipitation of morphology, size and distribution; 7. Analysis of the FTSR TMCP technology in the development of automobile production lines role and focus on the micro-alloy steel element boron on the performance of.Through the above work and related industrial test results of the analysis, it induces that in Nb, Ti-alloy steel reduced on the basis of C, Mn content at the same time add trace elements of B to balance the strength of steel, plastic, ductile-brittle transition temperature, and so on. Test of strength increase the effective solution of boron critical value of about 0 ppm, and the toughness of the critical value dropped about 6 ppm, the solution also gives the approximate formula Boron. Beam plate slab in the 800～900℃, the area reduction rate of only about 50 percent, was mainly due to this temperature range Nb, Ti, B-alloy elements in the grain boundary of the large number of precipitation. Taking with recrystallization and non re-crystallization area controlled rolling, grain mixed success to avoid the occurrence of the phenomenon. At the same time cooling speed after rolling control in 15℃/s around, grain size about 5～10μm, the organization for ferrite, little pearlite, bainite/acicular ferrite, retained austenite, better control of the strength and toughness of the relationship between the plastic. The newly developed high-strength automotive steel beam to achieve the average yield strength of 472 MPa, the average tensile strength to 543 MPa, Yield Ratio to 0.87, extending the average rate reached 23.9 percent.