Technological condition of high-manganese steel castings
High manganese steel castings are a kind of alloy castings, which are mainly composed of high manganese steel materials, and contain trace elements such as silicon, nickel and chromium. Most of them are pearlite low-carbon high-manganese steel and some are fully austenitic high-manganese steel. High manganese steel castings are widely used in various industries, such as engineering machinery, railway traction, marine engineering, chemical industry, cement and mine industry.
GB 5680-85 is the national standard for the control of the quality of high manganese steel casting. This requirement applies to the structure, requirements and inspection methods of the parts. The requirements for chemical composition, metallographic structure, mechanical properties and heat treatment of high manganese steel castings are all in.
The requirements for mechanical properties of high manganese steel castings are divided into three groups, namely wire rods, castings and forged parts. The strength requirements of the three groups are different. In the chemical composition of high manganese steel, the carbon content should not be too high and too low, the limit of carbon content is 0.90%-1.20%. In order to obtain a better metallographic structure of high manganese steel castings, it is necessary to adopt special smelting process and pouring system.
In order to ensure the performance of high manganese steel castings, normalizing or quenching and tempering is generally adopted for heat treatment of high manganese steel castings. According to the requirements of GB 5680-85, when the thickness of high manganese steel casting is less than or equal to 30mm, it should be heat-treated in the state of wall thickness. On the other hand, when the wall thickness of casting is greater than 30mm, heat treatment is required in the condition of reducing thickness by 10%.
For high manganese steel castings, the performance requirements can be perfectly met only when the foundry technology and casting quality are good, and the heat treatment process of high manganese steel castings should be strictly controlled. Therefore, it is necessary to make strict requirements on the control of the quality of high manganese steel castings in the production of GB 5680-85, including chemical composition, metallographic structure and mechanical properties, heat treatment and other aspects.
