THE HEAT TREATMENT PROCESS OF CONNECTING MEMBER MADE OF STAINLESS STEEL ON FITTING TUBE

摘要

A heat treatment method for producing a high quality connecting member for tube fitting is provided to simplify the operation process and improve connecting properties of tubes by improving wear resistance of a connecting member for tube fitting made of stainless steel and reducing a corrosion phenomenon generated on a surface of the connecting member, and improve corrosion resistance by regenerating a passive film damaged in the heat treatment process of the connecting member. A heat treatment method of a connecting member for tube fitting made of stainless steel comprises: a carbonitriding process(S1) performed on a surface of the connecting member by preheating the connecting member using nitrogen gas in a combined heat treatment furnace, nitriding the preheated connecting member in a nitrogen gas atmosphere, and subjecting the nitrided connecting member to the carbonitriding process using nitrogen, ammonia and propane gas, or nitrogen, ammonia and carbon dioxide gas; a decarburizing and denitriding process(S2) performed on the carbonitrided connecting member by decarburizing the carbonitrided connecting member using air and cooling the decarburized connecting member using nitrogen; a barrel grinding process(S3) performed on the decarburized and denitrided connecting member to improve the entire surface roughness of the connecting member by grinding the connecting member; and a passive film regenerating process(S4) of inspecting the grinded connecting member and regenerating a passive film on a surface of the inspected connecting member.