Research On The Resistance Spot Welding Performance Of22Mnb5High Strength Steel

The paper investigates the resistance spot welding performance of22MnB5high strength steel based on the original condition and the quenching condition. The spot welding experiment of22MnB5high strength steel is carried out based on different welding processes|and good welding joint is obtained Meanwhile, a series of experiments and simulations are conducted to study the spot welding joint.Firstly, by the use of orthogonal optimization method, the paper studies the spot welding performance of the original22MnB5high strength steel and the22MnB5high strength steel after quenching by the tensile test and obtains the mechanical properties in different parameter conditions. The results show that the optimal condition of the spot welding joint on the original22MnB5high strength steel is specimen thickness1.6mm, spot welding current9000A, spot welding time0.3s. The influential factors of the spot welding performance on the original.22MnB5high strength steel in descending order are spot welding current, specimen thickness, spot welding time. The optimal condition of the spot welding joint on the22MnB5high strength steel after quenching is specimen thickness1.6mm, spot welding current7800A, spot welding time0.4s. The influential factors of the spot welding performance on the22MnB5high strength steel after quenching in descendng order are specimen thickness,spot welding current, spot welding time.Secondly by the use of the finite element software named LS-DYNA, the paper carries out the spot welding tensile simulation of the original22MnB5high strength steel and the22MnB5high strength steel after quenching, explores the effective stress and the effective strain distribution of the spot welding. Thirdly, the paper carries out the hardness test of the spot welding on the original22MnB5high strength steel, finds out that the hardness distribution is not uniform at the nugget zone, the hardness values of the nugget zone are significantly higher than those)of the base material, the hardness values present a notable decrease at the heat affected zone. The paper also carries out the hardness experiment of the spot welding on the22MnB5high strength steel after quenching. The results show that the hardness distribution is not uniform at the nugget zone, the hardness values of the nugget zone are slightly higher than those of the base material, the hardness values present a)significantly transition at the heat affected zone. Fourthly, the paper conducts the microstructure analysis test of the spot welding on the original22MnB5high strength steel, the results demonstrate that the microstructure of the base material is mainly ferrite and pearlite, the microstructure of the heat affected zone is mainly ferrite, pearlite and martensite, the microstructure of the nugget zone is mainly lath martensite. The paper also conducts the microstructure analysis test of the spot welding on the22MnB5high strength steel after quenching, the results manifest that the microstructure of the base material is mainly fine lath martensite, the microstructure of the heat affected zone is mainly ferrite and a small amount of martensite, the microstructure of the nugget zone is mainly coarse lath martensite. Fifthly by the use of the finite element software ANSYS, the paper accomplishes the optimization task on the spot welding distance of the original22MnB5high strength steel, the results determine that the optimal distance is18mm～25mm; in addition, the paper also accomplishes the optimization task on the spot welding distance of the22MnB5high strength steel after quenching, the results ascertain that the optimal distance is18mm-25mm.