A method for removing defects in medium carbon steel castings

Abstract

The invention relates to the technical field of casting defect repair, in particular to a medium carbon steel defect removal method. The medium carbon steel defect removal method comprises the following steps: preheating of the surface of a casting, performing carbon arc gouging and magnetic powder detection in the high-temperature state, and then directly conducting recovery of the high-temperature casting by repair welding. According to the medium carbon steel defect removal method, an appropriate preheat temperature is selected for high-temperature carbon arc gouging according to the CCT (Continuous Cooling Transformation) curves of the medium carbon steel material together with the Ms point temperature, the Mf point temperature and gouging operability, so that the crack probability after carbon arc gouging is effectively reduced; and as high-temperature polishing, detection and recovery by repair welding are directly carried out after high-temperature gouging, the casting is further prevented from cracking, the preheating cost in the repair welding procedure is lowered and the production period is shortened.

Description

technical field [0001] The invention relates to the technical field of casting defect repair, in particular to a method for removing defects of medium carbon steel castings. Background technique [0002] In carbon steel materials, as the carbon content increases, the hardness and strength of steel increase, but its plasticity and toughness decrease, and the comprehensive mechanical properties of steel are hard and brittle. The main alloying elements of medium-carbon steel are C, Si, and Mn, and the carbon content is between 0.3% and 0.6%. The casting composition also contains a certain amount of Cr and Mo alloying elements. Therefore, the carbon equivalent of the material is close to 1.0%. When the carbon equivalent of steel reaches 0.6% or more, it is a brittle material with low plasticity and high hardening tendency. For this type of steel, when carbon arc gouging and arc welding are performed, hard and brittle martensite structures are likely to be formed in the heat aff...

AI Technical Summary

Problems solved by technology

The cracks have various forms, mainly single linear distribution or network distribution. Continuous carbon arc gouging cannot completely dig out the cracks, which will eventually lead to a large amount of welding repair, increasing the difficulty of welding repair and welding consumables. Use costs, increase the production cycle of castings, and even cause castings to be scrapped