Welded pipe welds are heat treated using high-frequency induction heating power. How to reduce the temperature difference between the inner and outer surfaces of the weld area?

We all know that when welded pipe welds are heated and heat treated using high-frequency induction heating power, the uniformity of the heating temperature is an important factor in ensuring the heat treatment effect. However, in actual operation, due to the influence of many factors, a temperature difference may occur between the inner and outer surfaces of the weld, thereby affecting the heat treatment effect of the weld. Today, the editor will tell you how to reduce the temperature difference between the inner and outer surfaces of the weld zone.

①Choose appropriate heating surface power density. The surface power density directly affects the heating speed. The greater the surface power density for heating, the faster the heating speed. The temperature difference between the inner and outer surfaces increases, and the time required for uniform temperature and heat penetration will be extended. Depending on the heat treatment speed, the appropriate surface power density is determined experimentally.

② Use grooved main coil for heating. After the surface power density is determined, the corresponding groove width should be determined according to the width of the heating weld zone to effectively heat the weld zone to avoid the heat treatment heating zone being too wide and affecting the treatment effect. When the base material of the pipe body is at an inappropriate heating temperature and inappropriate heat treatment is performed, the overall mechanical properties of the welded pipe will be reduced. This is especially important for induction heating quenching and tempering of welds.

③Prevent overheating in the weld heating zone. When low-carbon and low-alloy steel welds are heated by high-frequency induction heating power for normalizing or quenching, the grains will grow rapidly when the heating temperature is higher than 950°C. If the temperature exceeds 1000°C, overheating will occur, thus embrittlement of the weld metal. When the transverse magnetic field is heated to 950°C for high-temperature normalizing or quenching, local overheating is prone to occur. For this reason, comprehensive measures should be taken to avoid overheating in the weld heating zone. These measures include selecting appropriate surface heating power, using grooved main coil heating, increasing the distance between the main coil end face and the weld seam, etc.

④Add a heat preservation time to eliminate the temperature difference between the inner and outer surfaces. Set up a thermal insulation device during heat treatment processes such as normalizing, quenching, annealing, and tempering to eliminate the temperature difference between the inner and outer surfaces of the weld through thermal insulation to improve the heat treatment quality of the weld. This measure is especially important for quenching and tempering of welds.

This article briefly introduces the measures to reduce the temperature difference between the inner and outer surfaces of the weld area. Xudu manufacturers adopt the above measures for heat treatment. The quality of the welded pipe welds after heat treatment is good and meets the work needs.