Method and device for improving hardness of inner wall of steel tube

Abstract

The invention provides a method and device for improving hardness of the inner wall of a steel tube. A scanning type induction hardening process is adopted, heat treatment is carried out on the inner wall of the whole steel tube, an induction coil is placed on the steel tube, and the steel tube rotates and relatively moves relative to the induction coil; in the process that the steel tube and the induction coil relatively move, the induction coil is powered on to heat, and the heated steel tube is instantly subject to water spraying cooling after heating; the heating frequency is selected to range from 500 Hz to 2000 Hz; and the speed of movement of the steel tube relative to the induction coil is between 3 mm / s and 6 mm / s, and the rotating speed of the steel tube ranges from 5 rpm to 20 rpm. Compared with a conventional manner that heat treatment is carried out on the steel tube or the steel tube is not treated, the skin effect of induction heating is used, in the heating process, the temperature of the inner wall of the steel tune is high, the temperature of the outer wall is low, and a temperature gradient is formed; after water spraying cooling is carried out, the aim of improving the hardness and the abrasive resistance of the inner wall is achieved; and meanwhile the outer wall basically keeps mechanical properties of toughness, strength and the like of an original matrix structure.

Description

technical field [0001] The invention relates to the field of electromagnetic induction heating, in particular to a method and a device for increasing the hardness of the inner wall of a steel pipe. Background technique [0002] Steel pipes are widely used to transport oil, gas, and materials, so the hardness and wear resistance of the inner wall of the steel pipe directly determine the service life of the steel pipe. In order to improve the mechanical properties of metal materials, two methods of adding alloy elements and heat treatment can usually be used. In order to reduce costs in the production process, the two methods are often used in combination. The heat treatment can be divided into two types: conventional gas furnace heating and induction heating. The advantages of induction heating are high heating efficiency and fast heating speed, which can significantly improve product quality and speed up production rhythm. Therefore, it is increasingly favored by steel and ...

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Problems solved by technology

The above-mentioned patent does not involve specific process control parameters except that the installation position of the coil and the water spraying method of the patent of the present invention are different

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