Ferritic stainless steel for automobile exhaust emission system

Abstract

The invention discloses a ferritic stainless steel used for an automobile exhaust discharging system, wherein, the elements quality ratio is as follows: C is less than or equal to 0.02, Si is less than or equal to 1.0, Mn is less than or equal to 1.0, Cr is between 10.5 and 12.0, P is less than or equal to 0.03, S is less than or equal to 0.003, Ni is less than or equal to 0.3, Ti is less than or equal to 0.60 and larger than or equal to 6 multiplied by C+N, Nb 0.15 to 0.35, N is less than or equal to 0.01, C+N is less than or equal to 0.03, Fe and inevitable impurity as the rest. The invention adopts low carbon-nitrogen design route, and the ferritic stainless steel is added with Ti and Nb. Therefore, double stability not only improves corrosion-resistance, surface quality of the continuous casting billets, but also improves the comprehensive mechanical properties of the materials simultaneously. Smelting is much easier to achieve in the existing production line, the success rate is greatly increased, and the production cost is effectively reduced. By mechanical and corrosion testing of the steel product, the properties of the invention are better than single-stable low-chromium ferritic stainless steel .

Description

technical field [0001] The invention relates to ferritic stainless steel, in particular to an economical ferritic stainless steel with good corrosion resistance for automobile tail gas emission system. Background technique [0002] The automobile industry has developed rapidly in recent years. With the development of the automobile industry, the materials used in automobile exhaust systems have been paid more and more attention by automobile manufacturers to meet the increasingly stringent environmental protection requirements and the continuous reduction of body weight and material costs. Ferritic stainless steel has the advantages of comprehensive cost and performance, such as nickel saving, intergranular corrosion resistance, low thermal expansion coefficient, high strength and other physical and mechanical properties, so that ferritic stainless steel replaces austria. Stencilitic stainless steel has become the material of choice for automobile exhaust systems and has be...

AI Technical Summary

Problems solved by technology

[0014] In addition, the traditional Ti monostable ferritic stainless steel needs to add a relatively large amount of Ti due to the need to ensure the necessary stabilization effect, and the weight of Ti combined with N in molten steel to form TiN will easily cause nozzle nodules and cause pouring interruption , slightly affects the surface quality of the continuous casting slab

In order to eliminate its influence on the surface quality of the continuous casting slab, it is necessary to increase the amount of surface grinding of the continuous casting slab, which will inevitably increase the grinding cost and material loss; or reduce the N content in molten steel as much as possible, which also increases the cost of steelmaking. cost

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