Research Of Ultra High Strength Steel Plate Hot Stamping Die Fatigue Life

Hot stamping is a new technology which heating forming the boron steel and rapid cooling to obtain ultra high strength steel plate. At present, with the characteristics of light weight, high strength, the vehicle high strength and ultra-high strength steel plate used is more and more wildly in the car body, and has become the important way that meet the weight loss and increase the impact performance and safety performance. Hot stamping die as a new kind of hot-work die, is diffident with traditional hot-work die, to withstand higher temperatures, the alternating thermal stress is larger and more prone to metal thermal fatigue crack and thermal fatigue failure problem. Research the fatigue life of hot stamping die can reduce the cost of stamping and promote the competitiveness of the market. This article in hot stamping die as the research object, according to the ultra-high-strength steel cooling process of hot stamping, establish a finite element model of the cooling system in thermoforming mold, the size and distribution of thermal stress and thermal deformation of hot stamping mold were studied. Using ABAQUS to its pressure quenching phases coupled thermo-mechanical simulation, based on numerical simulation of orthogonal test design, examines the pipe diameter, the distance between the up profile, the distance between two pipes, and the distance between side profile of four factors on the impact of mold thermal stress and thermal deformation distribution and size. The configuration parameters of cooling water pipes were optimized, comprehensively considering the multi- index factors under different level, impact of the hot stamping die thermal stress and thermal deformation of the size of the optimal cooling water pipe arrangement. Finally, calculate the fatigue life of optimal hot stamping die model, and forecast its fatigue life, provide the data reference for the hot stamping die design.The article main research content is made up of the following parts:The first part: Simulated the cooling process of hot stamping die, using CATIA established a simplified model, import the date into ABAQUS to studied with finite-element analysis, get the size and distribution of thermal stress and thermal deformation of hot stamping die in the holding process.The second part: The configuration parameters of cooling water pipe of hot stamping die was designed based on orthogonal experiment, designed the cooling water pipe arrangement of four factors : the pipe diameter, the distance between the up profile, the distance between two pipes, and the distance between side profile which impact of mold thermal stress and thermal deformation distribution and size.9 group model is established, and finally analysis the date of test result, the impact of the hot stamping die thermal stress and thermal deformation of the size of the optimal cooling water pipe arrangement is got.The third part: Analysis the fatigue life of the hot stamping die model which adopt the optimal cooling water pipe arrangement, import the hot stamping die model which adopt the optimal cooling water pipe arrangement and result of stress into FE-SAFE to calculate the fatigue life, and predict the fatigue life of hot stamping die under the model, provide the reference data for the hot stamping die design.