Relying on ZHY casting, the company is a medium-sized private enterprise producing bridge bearing steel castings. The transfer casting process of bridge bearing steel casting is sodium silicate sand casting. Due to the influence of environmental protection situation, CO2 hardened sodium silicate sand process is facing the trend of elimination due to its poor regeneration and reuse of used sand and easy environmental pollution caused by the discharge of used sand. The lost foam casting process of green environmental protection and clean production has become the new direction of technology transformation of the enterprise.
Bridge bearing is an important structural component connecting the superstructure and substructure of a bridge. It can bear the rated vertical load and can rotate in all directions. According to the structure, it is mainly divided into plate rubber bearing, basin rubber bearing, spherical steel bearing and cylindrical steel bearing. The selection of bridge bearing forms and specifications should also consider the following factors: bridge span, fulcrum reaction force, requirements for building height, requirements for adapting to one-way and multi-directional displacement and displacement, and requirements for seismic protection, shock absorption and isolation. As the bridge bearing steel casting is a bearing structure component, its reliability will directly affect the safety and durability of the bridge, so the quality requirements of the bridge bearing steel casting are very strict, and there are no casting defects such as shrinkage porosity, cracks, pores, inclusions, etc. the stress parts of the steel castings should be subject to ultrasonic flaw detection and meet the class II standard. According to the different service environment, bridge bearing steel casting can be divided into conventional bearing, cold resistant bearing and corrosion-resistant bearing. The cast steel grades include zg230-450, zg270-500, zg20mn, etc., which belong to medium and low carbon steel or low-carbon alloy steel.
The purpose and intention of this study is to explore and solve the problem of carburization in the field of low-carbon steel casting, so as to broaden the application field of LFC in the production of high-quality low-carbon steel castings.