A study on the mechanical charecteristics of welded connections of bogie chassis for railcars

Today, railway vehicles have an important role in transportation area. Especially, subway transportation is commonly used in metropolitans as a public transportation. Welding is one of the most production system used in railway vehicles; and the walking parts called such as bogie and chassis are the most important parts. Bogies in this system arc exposed to failure during service. Hence, its repair and maintenance is required more care. The service lifes of these bogies, whose commercial names are Schlieren. Görlitz and Y32, are not expected and determined due to various factors affecting its service life. In this study, the fatigue behaviour of Schlieren type bogies used by TCDD was investigated for this reason, two types of specimens called original and welded were prepared and these were exposed to fatigue tests under 300, 400 and 500 M Pa stresses. Then the S-N (Wohler) curves of them were drawn as number of cycles vs. stres. In addition, the material characterization was done by evaluating microhardness values and metallographic examination. By doing so, the service life expectation of these bogies were tried to advise the customers. Selection of electrod and welding methods affect the microhardress and fatigue life of the bogie.