High-silicon-molybdenum-chromium spheroidal graphite cast iron material for automobile turbine housings and preparation method thereof

Abstract

The invention discloses a high-silicon-molybdenum-chromium spheroidal graphite cast iron material for automobile turbine housings and a preparation method thereof. The material comprises the following compositions in percentage by weight: 2.90-3.10% of carbon, 4.40-4.80% of silicon, less than 0.30% of manganese, less than 0.05% of phosphorus, less than 0.02% of sulfur, 0.03-0.05% of magnesium, less than 0.50% of nickel, 0.70-0.80% of chrome, 0.50-0.65% of molybdenum, less than 0.03% of aluminum, less than 0.10% of copper, less than 0.035% of titanium, and the balance of iron (Fe). The preparation method comprises the following steps: putting silicon carbide, pig iron, return materials and scrap steel into a smelting device; after the materials are melted, adding silicon iron, molybdenum iron and chromium iron into the smelting device to carry out refining; carrying out pouring and spectrum analysis on a taken melted material; continuing to heat up the smelting device, adding a low-sulphur recarburizer in the smelting device, and preparing a spheroidizing treatment; putting the obtained material into a spheroidizing bag to carry out wire feeding spheroidizing treatment; putting the spheroidized material into a pouring ladle to carry out inoculation treatment, removing oxidizing slags, and cooling the material; carrying out temperature-drop pouring and cleaning shakeout treatment on material liquid; and carrying out heat treatment on the obtained casting subjected to shakeout, carrying out annealing on the casting until the casting is at room temperature, thereby obtaining a finished product. The material is reasonable in formulation, the preparation process is simple and easy to implement, the prepared material is good in casting and machining performances, low in cost, and ideal in application effect.

Description

Technical field [0001] The invention relates to a production process method of a turbine shell material of an automobile turbocharger, in particular to a high silicon molybdenum chromium ductile iron material for an automobile turbine shell and a preparation method thereof. Background technique [0002] With the rapid development of turbocharging technology, its energy-saving and environmentally friendly characteristics are widely accepted by many automobile manufacturers. As one of its main components, the turbine housing has higher and higher requirements for high temperature resistance and corrosion resistance. The silicon-molybdenum-chromium ductile iron material has good high-temperature mechanical properties, corrosion resistance and cost performance. It is a good material for the production of turbine shells. However, the high-silicon-molybdenum-chromium ductile iron material has poor casting performance due to its high alloy content. In the case of turbine shell castings ...

AI Technical Summary

Problems solved by technology

[0002] With the rapid development of turbocharging technology, its energy-saving and environmental protection features are widely accepted by many automobile manufacturers. Silicon-molybdenum-chromium ductile iron has good high-temperature mechanical properties, corrosion resistance and cost performance, and is a good material for the production of turbine casings. However, high-silicon-molybdenum-chromium ductile iron has poor casting performance due to its high alloy content. For turbine shell castings with complex structure and uneven wall thickness, micro-shrinkage porosity is prone to occur in thin-walled parts, and shrinkage cavities and other defects are prone to appear in thick and large parts. tool usage cost

[0003] At present, the production process of high-silicon-molybdenum-chromium ductile iron mainly includes molten iron smelting, spheroidization treatment, inoculation treatment, pouring, cooling, sand cleaning, heat treatment and other processes. Due to the high alloy content of high-silicon-molybdenum-chromium ductile iron material, In the smelting process, the temperature requirement is high, and it is difficult to control the spheroidization and inoculation links, and casting defects such as poor spheroidization are prone to occur, which brings hidden dangers to the mass production of castings

Images