| In recent years, with the rapid development of the automotive industry, high-strength steel has drawn more and more attention. The high strength steel can ensure strength while reducing the weight of the car, achieving weight reduction of automobile. Quenching and Partitioning steel is a high-strength steel, which is without the addition of alloying elements, the tensile strength remains the same, but the shaping material is improved. After the Q & P process, the material contains residual austenite, the phase transformation induced shaping effect in the subsequent deformation process, the material can ensure the strength with some shaping.Salt bath in this article used in the Q & P process, studying of partition temperature, different points of time and bake hardening of Q & P steel structure and performance. Then test mechanical properties of the material by optical electron microscope, hardness tester, universal testing machine on microstructure. The main contents and achievements are as follows:1. Study partition temperature on Q & P Steel PerformanceThrough experimental study found that when the quenching temperature is 910℃, the partition temperature of 350 ℃, the tensile strength of the material is about 1000MPa, elongation close to 20%, strong plastic area of about 1.9GPa%. Thus, when the partition temperature of 350℃, the diffusion of carbon which provides ample power elements, such carbon element can be sufficiently diffused into the austenite, making the austenite structure can be preserved at room temperature.2. Study time on the partition Q & P Steel PerformanceWhen the partition temperature is low, the diffusion of carbon takes a long time, because the diffusion of carbon elements is not sufficient driving force. When the partition get a higher temperature, carbon diffusion process can be completed within a relatively short time, so that carbon can be sufficiently diffused into the residual austenite and austenite structure can be preserved at room temperature.3. Study bake-hardening properties of hot forming steelsMost of tempered martensite tissue in hot forming steel after hardening and baking. With the extension of the baking time, the value of BH tend to increase, up to a certain time in the future, the value of BH unchanged. The effect of baking time elongation of the material is small. With the extension of the baking time, the hardness of the material showed a downward trend. |
