마찰압접을 이용한 선박디젤엔진용

Abstract

Inertia welding is a solid-state welding process in which butt welds in materials are made in bar or cylinder form at the joint face, and energy required for welding is obtained from a rotating flywheel. The stored energy is converted to frictional heat at the interface under axial load. The quality of the welded joint depends on many parameters, including axial force, initial revolution speed and energy, amount of upset, working time, and residual stresses in the joint. Inertia welding was conducted to make the large piston rod. Due to material characteristics, such as, thermal conductivity and flow stress, on the two sides of the weld interface, modeling is crucial in determining the optimal weld geometry and parameters. FE simulation was performed by the commercial code DEFORM-2D. A good agreement between the predicted and actual welded shape is observed. It is expected that modeling will significantly reduce the number of experimental trials needed to determine the weld parameters, especially for welds for which are very expensive materials or large rod. Many kinds of tests, including macro and microstructure observation, tensile, hardness and fatigue test, are conducted to evaluate the quality of welded joints. Based on the results of the tests, it can be concluded that the inertia welding joints of the large piston rod are better properties than the base material.