Exothermic welding sand mold riser and preheating test method

The thermit welding sand mold riser comprises a sand mold contour lower surface used for being attached to the upper surface of the rail bottom of a steel rail, the sand mold contour lower surface is provided with a first riser body and a second riser body which are symmetrically arranged, and the first riser body and the second riser body are communicated and converged together in a sand mold. The sum of the opening areas of the first riser and the second riser is smaller than 416 mm < 2 >. According to the thermit welding sand mold riser and the preheating test method provided by the invention, the polishing amount and the polishing time of the residual riser rod of the joint are reduced, and a rail base angle steel rail base material is prevented from being bitten in the process of polishing and removing the residual riser rod of the joint; and the preheating test method further verifies that the riser of the exothermic welding sand mold has a good preheating effect, so that the mechanical property of a we