A method for improving the mechanical properties of steel plates through hot forming-sub-temperature quenching-partitioning process

Abstract

The invention relates to a method for improving the mechanical properties of a steel plate through a thermal forming-subcritical quenching-partitioning technology. According to the method for improving the mechanical properties of the steel plate through the thermal forming-subcritical quenching-partitioning technology, the steel plate is heated to a temperature over Ac3 at a certain rate, and the temperature is kept for a certain time; the steel plate is transferred into a stamping die for hot stamping forming and quenching treatment, the steel plate is quenched to a temperature (QT1) between Ms and Mf, and the temperature is kept for a certain time; the steel plate is reheated to a temperature between Ac1 and Ac3, and the temperature is slightly lower than Ac3 and kept for a certain time; then, the steel plate is rapidly quenched to a temperature (QT2) between Ms and Mf, and the temperature is kept for a certain time; then, the steel plate is reheated to a temperature slightly higher than the Ms, and the temperature is kept; and finally, the steel plate is quenched to the indoor temperature. By the adoption of the method for improving the mechanical properties of the steel plate through the thermal forming-subcritical quenching-partitioning technology, the new thermal forming-subcritical quenching-partitioning technology is formed through combination of a subcritical quenching capable of achieving ultra-fine treatment and toughening of composite tissue, a hot stamping forming technology and a quenching-partitioning technology, and the treated hypoeutectoid steel is multi-phase tissue provided with martensite, granular ferrite, retained austenite and M / A islands and has excellent mechanical properties. Besides, by the adoption of the thermal forming- subcritical quenching-partitioning technology, the production cost of products is low, and the performance and cost ratio is high.

Description

technical field [0001] The invention relates to a method for improving the mechanical properties of a steel plate, in particular to a method for improving the mechanical properties of a steel plate through a hot forming-subtemperature quenching-partitioning process. Background technique [0002] With the increasing energy crisis and the deteriorating environment, energy conservation and emission reduction have become a major problem for automobile companies. Therefore, the concept and technology application of automobile lightweight was born, and it has received extensive attention from current automobile companies. [0003] Authoritative research shows that if the weight of the vehicle is reduced by 10%, the fuel efficiency can be increased by 6%~8%; when the weight of the car is reduced by 100Kg, the fuel consumption per 100 kilometers can be reduced by 0.3~0.6L; when the weight of the car is reduced by 1%, the fuel consumption can be reduced 0.7%. In addition, every 100...

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Problems solved by technology

According to reports, the amount of plastic used in automobiles in developed countries such as the United States and Germany has reached 10% to 15%; while aluminum and magnesium alloys are mainly used in the form of castings or forgings in automobile engines, transmissions and other parts, but due to Due to the high manufacturing cost of aluminum and magnesium alloy parts, complex forming process and poor welding performance, aluminum and magnesium alloys have not been widely used in car body manufacturing, although automotive steel is now challenged by many new materials and impact, but considering the current technology and other factors, in the foreseeable future, high-strength steel will still be the mainstream material for automobile lightweight

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