Salt-bath hardening treatment method for obtaining supersaturated solid solution from stainless steel surface

Abstract

The invention discloses a salt-bath hardening treatment method for obtaining a supersaturated solid solution from a stainless steel surface, belonging to the field of surface treatment of stainless steel. The stainless steel is soaked and activated by using a 5V01.% HF (Hydrogen Fluoride) water solution and subjected to salt-bath hardening treatment for 8-10 hours below the temperature of 480 DEG C; the salt bath contains CNO<->, the mass concentration is controlled to be 50%-55%, and the salt bath also contains K2CO3, N2CO3, CO(NH2), Li2CO3 and other trace elements. As the salt bath adopted by the method disclosed by the invention has low melting point and good liquidity at a low temperature and the CNO<-> in the salt bath has relatively high reduction potential, the stainless steel is subjected to activation treatment and low-temperature hardening treatment below the critical temperature, and active nitrogen atoms have direct contact with the base body, thus a supersaturated solid solution hardened layer can be obtained, the hardened layer has an S-phase structural characteristic, the surface hardness of the hardened layer is three times the hardness of the base body; and the supersaturated solid solution hardened layer has higher corrosion resistance than austenitic stainless steel before the hardening treatment.

Description

technical field [0001] The invention relates to a salt bath strengthening treatment method for obtaining a supersaturated solid solution on the surface of stainless steel, belonging to the field of surface treatment of stainless steel. Background technique [0002] The Cr element in stainless steel can be oxidized in the air to form Cr with strong self-healing ability 2 o 3 Passive film, so it has strong corrosion resistance and is widely used in engineering materials. However, a very obvious shortcoming of austenitic stainless steel is that the hardness of this material is not high, which is directly manifested in low surface hardness, wear resistance and fatigue resistance, which seriously affects the application range and service life of austenitic stainless steel. Surface hardening treatment is required for austenitic stainless steel. [0003] In the past, the surface strengthening treatment of austenitic stainless steel used conventional nitriding, carburizing or nit...

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Problems solved by technology

The gas method needs to use HCI or NH before carburizing 4 CI removes the passivation film on the surface of stainless steel, which will seriously pollute the environment; the ion method removes the passivation film on the surface of stainless steel by ion bombardment, and infiltrates nitrogen (carbon) into the surface of stainless steel to obtain a hardening treatment that does not reduce corrosion resistance, but In large-scale ion nitriding (carbon), the temperature measurement and temperature uniformity of the workpiece in the furnace are difficult to control, which increases the difficulty of processing. Therefore, although the research on low-temperature ion hardening treatment of austenitic stainless steel has a history of decades, But there are not many examples of industrial applications

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