Thermal treatment method of 7CrSiMnMoV diameter expanding cone

Abstract

The invention discloses a thermal treatment method of a 7CrSiMnMoV diameter expanding cone. The thermal treatment method comprises the following steps: (1) completing preparation operation, namely, plugging holes and grooves, and coating a high-temperature resisting anti-oxidation coating; (2) feeding the 7CrSiMnMoV diameter expanding cone into a tool of which the bottom is a plane in a manner that the large end of the 7CrSiMnMoV diameter expanding cone faces downwards, putting the tool into an atmosphere protection heating furnace, introducing nitrogen to expel air, and completing the furnace feeding operation; (3) controlling the heating speed and the temperature, introducing nitrogen, ammonia gas and methanol, and heating; (4) controlling the heating time, the temperature and the time, introducing nitrogen and methanol for protection, and austenitizing; (5) controlling the time and the temperature, and performing nitrate quenching; and (6) controlling the time and the temperature, and annealing. The 7CrSiMnMoV diameter expanding cone treated by using the thermal treatment method is free of defect such as quenching cracks and decarburization, parameters such as the quenching depth, the bending resistance, the pressure resistance, the impact toughness and the hardness, of the material of the cone, are remarkably improved, the requirements on mechanical processing are met, and no deformation is caused after mechanical processing.

Description

Technical field [0001] The invention relates to a heat treatment method for a 7CrSiMnMoV expanded cone, in particular to a heat treatment method for a 7CrSiMnMoV expanded cone with a complicated shape. Background technique [0002] Diameter expansion die for mechanical expansion machine-Diameter expansion cone is a very critical mold for forming steel pipes. At present, our country is mainly purchased from German SMS MEER company and Dutch FONTIJINE GROTNES company. It is required to be able to expand 30,000 to 40,000 stably. support. [0003] During the expansion process, in order to make the steel pipe expand and deform, the expansion cone needs to withstand huge pressure and friction. In order to ensure the use performance of the expansion cone, currently cast NiCrMoCu antifriction cast iron and carburized 38CrMoAlA alloy steel are used preparation. Due to the complex shape of the expanding cone, the length can reach 1300 mm, the minimum thickness can reach 10 mm, and the maxi...

AI Technical Summary

Problems solved by technology

Cast NiCrMoCu anti-friction cast iron has many casting defects, and cracks and other defects are prone to occur during quenching; carburizing 38CrMoAlA alloy steel is deformed during carburizing and quenching, which can easily lead to subsequent mechanical processing to process the carburized layer on the working surface, reducing diameter expansion Defects in the wear resistance of the cone

The cracks and low wear resistance of cast NiCrMoCu anti-friction cast iron and carburized 38CrMoAlA alloy steel expansion cone seriously affect the production efficiency of steel pipes. Loss