Experimental Study On Mechanical Properties of Rail Thermit Welding Joints At Low Temperature

At a low temperature, the mechanical properties of thermit welding joints of rail steels get worse and brittle failures happen more easily. This threatens the railway transportation seriously. It is necessary to find out the mechanical properties of thermit welding joints of rail steels at low temperature because there are more and more railway constructions at low temperature such as Qinghai-Tibet railway. This paper studied the mechanical properties of tow common types of thermit welding joints in China, whose mother metal are U71Mn and U75V of 60kg/m, and got the Tensile strength, Proof strength (nonproportional extension), Percentage elongation after fracture and Percentage reduction of area of the tow types of thermit welding joints at a series of low temperatures. Temperature sensitivity coefficients of the two types of thermit welding joints were calculated and then the tensile strengths and proof strengths at low temperature could be forecasted. At last, which type of rail steel should be chosen at low temperature was proposed through the comparison of U71Mn and U75V thermit welding joints.