The advantages of using medium frequency induction diathermy furnace for induction heating solution treatment of steel

Now, when it comes to solution treatment of steel, many people will say to use a medium frequency induction diathermy furnace. Using this equipment for solution treatment has various advantages. So, what are the advantages? Today, the editor will tell you about the advantages of using medium frequency induction diathermy furnace for induction heating solution treatment of steel.

Today, the editor will take 21-4NWNb steel as an example and briefly tell you what characteristics the 21-4NWNb steel with induction heating solution treatment has compared with solution treatment in electric heating furnaces and gas heating furnaces.

(1) There is less oxidation and no decarburization on the steel surface. No decarburization was found on the surface of the steel that was subjected to induction heating solution treatment using a medium frequency induction diathermy furnace. However, there was a low carbon layer of about 0.10mm on the surface after traditional heating solution treatment. Regarding the oxidation amount of steel after solution treatment, oxide scale appears on the surface of steel after traditional heating and solution treatment, and the yield rate is reduced by 0.15% to 0.20%; no oxide scale is found in induction heating, only an obviously dense oxide film.

(2) Room temperature mechanical properties of steel. The mechanical properties after ordinary heating solution treatment and induction heating solution treatment are at the same level. However, the quality of the steel used for induction heating is smelted in an electric arc furnace, and its metallurgical quality is much lower than that of steel smelted in a vacuum induction furnace. This shows that induction heating solution treatment bridges the gap in steel quality and shows the advantages of induction heating solution treatment.

(3) High temperature durable strength of steel. The lasting fracture times under 750°C and 150MPa stress after different heating solution treatments and aging treatments using the same method are listed in Table 1 below. The data in Table 1 shows that although the electric furnace heating solid solution aging treatment uses steel samples with better metallurgical quality than the electric arc furnace, its lasting fracture time is much shorter than that of the induction heating aging treatment samples. This data is the average of three samples, which fully shows that induction heating solution treatment can significantly improve the high-temperature durable strength of steel. The reason is that after induction heating solution treatment in a medium frequency induction diathermy furnace, the grains of the steel are refined, the grain size is uniform, and the mixed crystal phenomenon is very slight, which is beneficial to improving the grain boundary strength.

Table 1 High temperature durability characteristics after solid solution aging treatment (750℃, 150MPa stress)

(4) Grain size of steel. In order to ensure the high-temperature plasticity of the valve-making upsetting process, the grain size of the valve blank should be controlled at level 6-7, and the grain size should be uniform to reduce the phenomenon of mixed crystals with different grain sizes. Mixed crystals are one of the main causes of high-temperature deformation cracking. Therefore, solution treatment of valve steel places strict requirements on grain size and mixed crystals. Table 2 shows the relationship between different solution treatment methods and the grain size of 21-4NWNb steel. Induction heating solution treatment at 1100-1150°C can control the grain size to an ideal level of 6-8, and the grain size is uniform, and mixed crystal phenomena that affect high-temperature plasticity rarely occur.

Table 2 Relationship between solution treatment temperature and grain size of 21-4NWNB steel

After reading the above description, I think you already know the advantages of induction heating solution treatment. It solves many heat treatment defects of traditional equipment and has developed into a widely used heat treatment method at present. It should be strongly promoted.