Characteristics of isothermal quenching heat treatment of steel wire using medium frequency induction heating equipment

Steel wire is widely used in industry. In order to meet the needs of the work, the steel wire needs to be austempered and heat treated. If you observe carefully, you will find that different manufacturers use different equipment for heat treatment, some use traditional equipment, and some use new medium-frequency induction heating equipment. So, which heat treatment equipment is better?

In order to clarify whether it is better to use medium frequency induction heating equipment for isothermal quenching heat treatment or traditional equipment, we specially analyzed the characteristics of induction heating isothermal quenching steel wire and traditional heating isothermal quenching steel wire. Their characteristics are as follows:

(1) Austenite grain size When high carbon steel wire is treated with sorbitization, the smaller the initial austenite grain size, the smaller the spacing between sorbite lamellae obtained after isothermal decomposition, and the higher the strength and toughness of the steel wire. . Therefore, it is necessary to strive to obtain fine grain size during the austenitizing heating process. Table 1 shows the analysis results obtained when austenitizing high carbon steel wire using different heating methods. From the data in Table 1, it can be seen that when the heating temperature is 950°C, as the heating speed slows down, the austenite grains coarsen, and induction heating can obtain 7-7.5 grade grains. The grain size during traditional heating is only It is level 5. When the heating rate is constant, the grains grow sequentially as the heating temperature increases. In terms of controlling the initial grain size of austenitization, induction heating is superior to traditional heating. Usually, the heating rate of induction heating austenitization is 200-400℃.S-l, and the heating temperature is 900-950℃.

Table 1 Effect of different heating rates and temperatures on austenitizing grain size

(2) Pearlite lamellar spacing of isothermal decomposition products. Table 2 shows the effect of austenitizing heating method on the spacing of pearlite lamellae of the isothermal decomposition product of lead bath quenching. From the pearlite lamellar spacing in Table 2, it can be seen that induction heating can refine the lamellar spacing, while the lamellar spacing obtained by traditional heating is larger. However, the lamellae obtained by the two heating methods indicate that they all belong to troostite, because troostite is a finer structure of pearlite, and its lamellar spacing is 30-80mm. Since the grains obtained by induction heating austenitization are relatively small, the products produced by isothermal decomposition have high dispersion, that is, the spacing between lamellae is small, and the tensile strength and yield strength of the final steel wire are higher than those of traditional heated lead bath quenching steel wire.

Table 2 Effect of austenitizing heating method on the spacing of pearlite lamellae in high carbon steel

In summary, it can be seen that induction heating austenitization is better than traditional heating austenitization. The advantage of induction heating is that rapid heating refines the initial austenite grains, which lays good organizational conditions for obtaining fine isothermal decomposition products. During troostite treatment, the smaller the initial austenite grains and the higher the dispersion of the troostite structure (actually troostite), the better the strength and toughness of the steel wire.

In short, the use of medium frequency induction heating equipment for isothermal quenching heat treatment of steel has greater advantages than traditional equipment. If you are still using traditional equipment for heat treatment, what are you waiting for? Quickly change to a medium frequency induction heating equipment with excellent effect.