Mechanical and metallurgical properties of welding zone in rail welded via thermite process

Abstract

The quality of railway construction is an important factor in providing safe and comfortable rail transportation. Thermite welding, which is a long established technique, prevents rail failure and derailing of trains. This technique assists in providing a smooth ride and long service life for rails and railway carriages. In the present study, type S49 SAE/AISI 1050 steel rails have been welded via a short preheating thermite process.The hardness distributions of the upper surface and inside sections of the welding zone have been obtained and its microstructure has been examined. In addition, specimens taken from the upper side (head), web, and base of the welding zone were subjected to tensile and Charpy V notch impact tests. In the hardness profiles for these specimens maximum hardness values were observed at the edges of the weld metal. The hardness values were 109 HB at the interface between the melting zone and the heat affected zone, 108 HB in the melting zone, and 104 HB in the unwelded rail region. Examination of the microstructure revealed proeutectoid ferrite and pearlite, but not martensite.