Process analysis of cutting tools using high-frequency induction heating power for preparatory heat treatment and quenching heat treatment

Tool heat treatment is an important link in tool production and manufacturing, and its quality is directly related to the economic benefits of the enterprise and the success or failure of market competition. Therefore, it is very important to master the heat treatment process of cutting tools. Today, the editor will tell you about the process analysis of heat treatment of cutting tools using high-frequency induction heating power.

There are many heat treatment processes for cutting tools using high-frequency induction heating power. I will not describe them one by one here. I will briefly introduce the heat treatment process of cutting tools by taking the more common preparatory heat treatment and quenching heat treatment as examples.

1) Preparatory heat treatment of high-speed steel. Preparatory heat treatment includes three categories: annealing, quenching and tempering, and stress relief annealing.

High-speed steel, also known as wind steel, can be quenched in the air when heated above the phase transformation temperature. It has a high hardness after rolling and forging. In order to soften it and facilitate cutting, it must be annealed. For tools with complex shapes, large cutting volumes, or slender, flaky tools, in order to reduce heat treatment distortion or quenching cracks, high-frequency induction annealing power is often used to perform stress relief annealing at 550-600°C.

In order to improve the cutting performance of the high-speed steel blank, especially the milling performance, it is necessary to undergo incomplete heating quenching and high-temperature tempering to make the blank reach a hardness of 32-38HRC.

The temperature must be controlled during preparatory heat treatment to avoid oxidation and decarburization.

2)Quenching and tempering treatment of high-speed steel cutting tools. The impact of fixtures on heat treatment quality has attracted more and more people's attention. Suitable fixtures should be designed and manufactured for different tool quenching. Some tools are very difficult to heat treat, and the difficulty lies in the quenching fixture.

High-speed steel contains more alloy elements and has poor thermal conductivity, so it needs to be preheated twice or even three times. When using high-frequency induction heating power supply for preheating, the preheating temperature is generally 850-870℃, and the preheating time is twice the heating time.

For tools of different types, specifications and usage conditions, the selection of quenching heating temperature and heating time should be based on the austenite grain size and carbide dissolution degree in order to obtain a better comparison of wear resistance, hot hardness and toughness. optimal fit to maximize tool life.

The secondary hardening peak of most high-speed steels is around 550°C, so the tempering temperature is generally set at 550°C. The tempering medium is 99% NaNO3 or 99% KNO3 solution. Due to the large amount of retained austenite in isothermal quenching, 4 times of tempering are required. After tempering, it must be cooled to room temperature before the next tempering can be performed. Most of the hardness of high-performance high-speed steel will exceed 68HRC after tempering at 550°C, but super-hard high-speed steel cannot be super-hard. If it exceeds 68HRC, it is generally better to increase the tempering temperature to 590°C and lower it to 67.5-67HRC.

This article briefly introduces the preparatory heat treatment and quenching heat treatment process of cutting tools. If you still don’t understand anything, you can consult our technical staff or read relevant books. I believe you will gain a lot.