Method for improving intergranular corrosion resistance capacity of austenitic stainless steel

Abstract

The invention provides a method for improving the intergranular corrosion resistance capacity of austenitic stainless steel. The method comprises the following steps that sensitization treatment is carried out, specifically, heating treatment and sensitization treatment are carried out on the austenitic stainless steel, so that chromium carbide is separated out between crystal particles, and the sensitized stainless steel is obtained; the sensitized stainless steel is continuously heated to 880 DEG C-950 DEG C through atomic diffusion treatment, and the stainless steel is subjected to heat preservation; and then the stainless steel is cooled to the room temperature. According to the method, the chromium carbide is separated out between the crystal particles of the austenitic stainless steel through sensitization treatment firstly, so that the content of chromium between the crystal particles is low; then chromium atoms in the austenitic stainless steel crystal particles are diffused tothe crystal boundary through atomic diffusion treatment, so that the intergranular barren chromium phenomenon is eliminated, and the intergranular corrosion resistance is achieved in a stable state;and the method has the advantages that the heating temperature is low, the fuel consumption is low, the thermal forming process does not need to avoid a sensitization region, the equipment requirementis low, normalizing treatment can be carried out with a carbon steel material at the same time, the cost is low, and chemical components of an austenitic stainless steel material do not need to be changed.

Description

technical field [0001] The invention relates to a processing method for stainless steel materials, in particular to a method for improving the intergranular corrosion resistance of austenitic stainless steel. Background technique [0002] Austenitic stainless steel refers to stainless steel with austenitic structure at room temperature. When the steel contains about 18% of Cr, 8% to 25% of Ni, and about 0.1% of C, it has a stable austenite structure. Austenitic stainless steel has high corrosion resistance, mainly due to the addition of Cr and Ni. The added Cr and Ni react with oxygen in the air to form a dense oxide film on the surface. This oxide film has high stability in many corrosive media, thus preventing the steel itself from being corroded by corrosive media. But under certain conditions, it will also be corroded. Intergranular corrosion is one of the corrosion forms, which is a selective corrosion phenomenon that occurs near the grain boundaries. Although the s...

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Problems solved by technology

This method is currently the most commonly used method to improve the intergranular corrosion resistance of austenitic stainless steel without stabilizing elements. This method has high production costs, causes product deformation, and is difficult to repair. Can not meet the requirements, so the scope of application of the austenitic stainless steel treated by this method is limited, and the high temperature will easily cause the growth of the crystal material, resulting in the decline of mechanical properties, and cannot be refined by heat treatment. Once it occurs, the probability of product scrapping is very high, and The solid solution state is an unstable state, which is easily destroyed during subsequent production and use

The second is to strictly control the carbon content and reduce the carbon content of austenitic stainless steel. This method produces raw materials and smelting costs are high

Although this invention patent application can reduce the formation of an appropriate amount of δ ferrite in the heat treatment process of austenitic stainless steel, reduce the sensitization degree of austenitic stainless steel, improve the resistance to intergranular corrosion, and can be used in large-scale industrial production, but its second The heating temperature of the stage and the third stage exceeds 1000°C, the heating time is relatively long, the energy consumption is large, and the cost is high

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