Experimental Study on Mechanical Properties of Rail Thermit Welding Joints at Low Temperature

摘要

At a low temperature, the mechanical properties of thermit weldingrnjoints of rail steels get worse and brittle failures happen more easily.rnThis threatens the railway transportation seriously. It is necessary tornfind out the mechanical properties of thermit welding joints of railrnsteels at low temperature because there are more and more railwayrnconstructions at low temperature such as Qinghai-Tibet railway. Thisrnpaper studied the mechanical properties of tow common types ofrnthermit welding joints in China, whose mother metal are U71Mn andrnU75V of 60kg/m, and got the Tensile strength, Proof strength (nonproportionalrnextension), Percentage elongation after fracture andrnPercentage reduction of area of the tow types of thermit welding jointsrnat a series of low temperatures. Temperature sensitivity coefficients ofrnthe two types of thermit welding joints were calculated and then therntensile strengths and proof strengths at low temperature could bernforecasted. At last, which type of rail steel should be chosen at lowrntemperature was proposed through the comparison of U71Mn andrnU75V thermit welding joints.