A Method for Establishing Limit Diagram of Hot Forming of High Strength Steel Plate

Abstract

The invention relates to an establishment method of a high-strength steel plate thermoforming limit diagram. The method is characterized by comprising the steps of A. heating the reagent up to 950 DEG C in a sealing box 3, and carrying out heat preservation for 5min so as to enable the reagent to be completely austenitized; after that, cooling the reagent to the temperature needed to be measured in the experiment; B. establishing the forming limit lines of a high-strength steel plate in a single-drawing state, a double-isometric drawing state, a plane strain state and an intermediate state at all temperature by an expanding model in the sealing box; C. for the forming limit lines at the temperature below 400 DEG C, cooling the reagent to the temperature needed to be measured in the experiment at the cooling speed higher than the critical cooling rate vk so as to generate martensite phase transformation, and calculating to obtain the result; D. connecting the forming limit lines at all the temperature into two curved surfaces in origin software by a difference value method, and defining the two curved surfaces as a three-dimensional forming limit surface. After the establishment method of the thermoforming limit diagram is adopted, the thermoforming performance of the high-strength steel plate can be judged, and the higher the forming limit surface is, the better the thermoforming performance of the high-strength steel plate is.

Description

technical field [0001] The invention relates to the field of thermal forming processing of metal plates, in particular to a method for establishing a limit diagram of thermal forming of metal plates. Background technique [0002] High-strength steel generally refers to steel with a cold-rolled tensile strength above 340MPa, a hot-rolled tensile strength above 370MPa, or a yield strength above 210MPa. Due to its high specific strength and good anti-collision performance, it can greatly reduce the weight of automobiles under the same safety conditions, so it has attracted widespread attention in the automobile manufacturing industry. However, high-strength steel plates have poor formability at room temperature and are prone to defects such as wrinkles and cracks. Therefore, hot forming processes are usually used to deform them to obtain qualified parts. [0003] In the normal temperature forming process, there are many ways to evaluate the formability of the sheet, among whic...

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Problems solved by technology

[0008] The problem to be solved by the present invention is to provide a method for establishing the hot forming limit diagram of high-strength steel plate, which can not only solve the forming performance evaluation problem that can be solved by traditional forming limit diagram, but also provide a method that can accurately and conveniently evaluate the hot forming process of high-strength steel plate Wrinkling and cracking problems in

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