Heat-resistant steel for automobile turbine shell and exhaust pipe and preparation method of heat-resistant steel

Abstract

The invention discloses heat-resistant steel for an automobile turbine shell and an exhaust pipe and a preparation method of the heat-resistant steel. The heat-resistant steel comprises the following chemical components in percentage by mass: 0.2-0.5% of carbon; 1.0 to 2.5 parts of silicon; 3.0 to 8.0 parts of manganese; less than or equal to 0.040 of phosphorus; 0.02 to 0.15 part of sulfur; chromium: 22.0 to 27.0%; 6.0 to 10.0 parts of nickel; 0.20 to 0.50% of nitrogen; 0.10 to 0.50% of niobium; 0.50% or less of molybdenum; 0.50% or less of vanadium; 0.005 to 0.050 percent of aluminum and the balance of iron and inevitable trace elements. According to the invention, a proper amount of sulfur element is added into the heat-resistant steel material, and the sulfur element and the manganese element are combined to form manganese sulfide, so that the manganese sulfide can play a role of a solid lubricant in the processing process, thereby improving the processing performance of the low-nickel sulfur-containing casting chromium-manganese-nitrogen austenitic heat-resistant steel, and reducing the reject ratio of slag holes of the product and the processing cost of the low-nickel sulfur-containing casting chromium-manganese-nitrogen austenitic heat-resistant steel.

Description

[0001] This application is a divisional application of an invention patent application with a filing date of November 05, 2019, an application number of 201911068195.2, and an invention title of "heat-resistant steel for automobile turbine shells and exhaust pipes and its preparation method". technical field [0002] The invention relates to automobile accessories, in particular to a heat-resistant steel used for automobile turbine shells and exhaust pipes and a preparation method thereof. It belongs to the field of mechanical casting. Background technique [0003] At present, the turbine casing and exhaust pipe for automobiles are usually made of chromium-nickel austenitic heat-resistant steel. Elements to obtain good high temperature mechanical properties and oxidation resistance. Due to the high price of nickel as a raw material, the production cost of turbine shells and exhaust pipes for automobiles is relatively high. Therefore, it is considered to use low-cost element...

AI Technical Summary

Problems solved by technology

The use of manganese to promote and stabilize austenite, although it reduces the production cost of heat-resistant steel in the turbine casing and exhaust pipe of automobiles, but due to the high content of manganese in heat-resistant steel, during processing, Turbine shells and exhaust pipes are prone to work hardening, which increases the difficulty in the machining process of turbine shells and exhaust pipes, resulting in a significant increase in the cost of machining tools

Moreover, with the increase of manganese element, in the smelting and pouring process, the manganese element in molten steel is easily oxidized to form manganese oxides, and casting defects such as slag holes are easily formed after the molten steel is poured into the mold; and due to Manganese oxide is alkaline, and casting materials generally use acidic materials, so that manganese oxide reacts with casting materials, and casting defects will be formed, which reduces the yield and increases manufacturing costs

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