What are the Cooling Characteristics and Quenching Medium of Heat Treatment?

Mineral oil is usually used as cooling medium for heat treatment of rolling bearing parts. Mineral oil is composed of paraffin, naphthene, aromatic and paraffin aromatic hydrocarbons and various derivatives. According to the cooling speed, service temperature, brightness and other use requirements of quenching oil, it can be divided into the following five categories:

1. Cooling speed

Cooling speed is very important because it can directly affect the surface hardness and depth of the quenching layer after quenching. According to the cooling speed, quenching oil can be divided into three levels: ordinary, fast and ultra-fast.

Ordinary quenching oil is a commonly used oil in heat treatment production. It has a relatively slow cooling speed. Ordinary quenching oil is usually used in small and medium-sized bearing rings and rollers with low quenchability requirements.

Fast quenching oil can improve the hardness and depth of the quenching layer of bearing parts after quenching, and improve the mechanical properties of materials. It can be used for medium and large bearing parts made of GCR15 steel with large cross-sections, as well as quenching cooling of carburizing and carbon-nitrogen co-osmosis.

Overspeed quenching oil has a relatively fast cooling speed. In production, it is mainly used for bearing parts with large cross-sections and deep quenching layers.

2. Usage temperature

The service temperature of quenching oil will affect the service life of the oil, the quenching cooling speed, motion viscosity and the deformation degree of parts. Quenching oil used below 80 °C is called cold quenching oil, and quenching oil used in the temperature range of 8 °C to 120 °C is called thermal quenching oil, also known as graded quenching. Because graded quenching oil is used at higher temperature conditions, it generally has a high flash point and viscosity, and contains antioxidants, which makes it have a long service life in harsh working environments. In actual production, it is mainly used in bearing parts that require small deformation.

3. Vacuum quenching oil

Vacuum quenching oil is used to quench and cool heating parts under vacuum conditions. Vacuum quenching oil has low saturated steam pressure, good brightness and hardening.

4. Fast brightening quenching oil

Fast bright quenching oil is a kind of bright quenching oil with strong cooling performance. When the oil temperature is at 80 °C, its characteristic temperature is not less than 600 °C, and the cooling time from 800 °C to 400 °C is not more than 4.5s. It is mainly used for bright quenching on the surface of bearing parts with controllable atmosphere or protective atmosphere heating.

5. Mechanical oil

Mechanical oil is a refined mineral lubricant. Because of its low price and easy purchase, there are still many manufacturers using this oil in the bearing industry. The commonly used mechanical oils are N32(20#) mechanical oil and N15(10#) mechanical oil and some additives.

The author of this article is Shaanxi Gainhui Heavy Industries Co., Ltd., which is a professional bearing manufacturer and supplier in China. The company supplies many types of the bearings, such as pillow block housing units ucf series, timken spherical roller bearings, etc. With high quality and competitive bearing products, we sincerely provide services to customers all over the world.

Contact us for more details:

E-mail: emily@gainhui.com

Tel: +86-029-88692376

Mob/WhatsApp: +86-18710850036