Analysis On Q235Steel Flash Welding Temperature Field And Research On The Performance Of Welded Joint

Flash welding is a reliable connection method, which has many advantages: the jointquality is good, the mechanical properties of welded joint are close to the base material, and itis facilitated and controlled easily. The flash welding technology has been widely applied inrail transportation, pipeline, construction and other fields. The most important factor to affectthe performance of flash welding includes the temperature distribution of the weld area, flashprocess parameters and weld microstructure defects. Temperature field distribution of weldedweldment plays a crucial role in the quality of welded joints. Therefore, studying flashwelding temperature field distribution is significant to improve the joint performance andavoid weld defects.In this article, a thermoelectric coupling finite element model with the finite elementsoftware was built to simulate temperature field distribution in Q235steel flashing process.During the calculation, the temperature of the material phase changes and the thermophysicalproperties are taken into account to solve the burning substance when flashing. Draw theconclusion of the temperature field over time during the welding process, as well as thetemperature field distribution characteristics of the weldment axially and radially,and the temperature field distribution was verified by a real-time infrared thermoscopeexperience. The result shows that the simulated result and the measured values are identical, itis accurate reflection of the actual process of Q235steel flash welding.Analysis of the Q235steel flash welded joint performance: the average tensile strength ofwelded joint was higher than the base metal, while the plastic toughness of welded joint wasworse than the base metal. The thermal cycling curves of different points in the weldmentleaded to the regional grain difference. The microscopic hardness test showed that themicrohardness of the weld zone and heat affected zone were higher than the base metal, themaximum microhardness value was in the weld zone, the size of grain was increasinggradually along the axial line in heat affected zone. Furthermore, studying on microstructureof Q235steel welded joint, we found that the tissue morphology of the welded joint are mainly the ferrite and pearlite, the intermediate tissue was increasing gradually along the axialline in the heat-affected zone, The number of pearlite in the heat affected zone was graduallydecreasing, and the mesh widmanstatten tissues were distributed here, reducing the ductilityand toughness of the welded joints.