A brief analysis of the impact of induction quenching using high-frequency induction heating machines on the impact properties of quenched parts

Induction quenching using a high-frequency induction heating machine to refine the structure can significantly improve the impact toughness of the material, which has been proven by experiments. This is mainly achieved by reducing the brittle transition temperature of the material. At a certain test temperature, if coarse-grained materials undergo impact brittle fracture, those with refined grains may transition to ductile fracture, thereby increasing the impact toughness. Above the brittle transition temperature, the effect of grain size on impact toughness is not great. The following table shows the effect of single-sided surface quenching on the impact toughness of Charpy (V-notch) impact specimens of 40 steel and 40Cr steel. It can be seen from the table that when the single-sided quenching depth is 20% to 30% of the cross section, the impact toughness of the original normalized sample is reduced by 50%, and the impact toughness of the original quenched and tempered sample is reduced by 10% to 30%. But the relative value of impact toughness is still quite high.

The impact resistance of induction heating surface evaluation samples using a high-frequency induction heating machine was compared with carburizing and quenching samples. The impact test using 10mm*10mm unnotched samples showed that when 45 steel and 40Cr steel were surface quenched When the hard layer depth is 1.1~2mm and the impact toughness is 59J/cm2, it can reach 98J/cm2 after tempering at 130℃. The impact toughness of 20 steel and 20Cr steel samples that are carburized, quenched and tempered at low temperature is lower than 29~39J/cm2. The above test results show that although surface quenching using a high-frequency annealing machine will reduce the impact toughness, it is not as reduced as the carburized sample.