Heat-treatment oil composition

Abstract

A heat-treatment oil composition can make it possible to achieve both high quenching hardness and reduced quenching distortion. A heat-treatment oil composition may include a base oil (A) and a vapor film rupturing agent (B). The heat-treatment oil composition may make it such that, on a cooling curve obtained in accordance with the cooling performance test method in JIS K2242:2012, the time in seconds to 300° C., e.g., the cooling time from 800 to 300° C., is less than 6 seconds. Component (B) may include a petroleum resin.

Description

TECHNICAL FIELD[0001]The present invention relates to a heat-treatment oil composition.BACKGROUND ART[0002]A metal material such as a steel material is subjected to a heat treatment such as quenching, tempering, annealing and normalizing for the purpose of improving properties thereof. Among these heat treatments, quenching is a treatment for transforming a heated metal material to a predetermined quenched structure by immersing the metal material in a cooling medium, and this quenching makes the treated product very hard. For example, when a heated steel material in an austenite state is cooled at the upper critical rate or higher by immersing in a cooling medium, the material can be transformed to a quenched structure such as martensite.[0003]As the cooling medium, an oil-based or water-based heat treatment agent is generally used. Quenching of a metal material using an oil-based heat treatment agent (heat treatment oil) will be described. When a heated metal material is put into ...

AI Technical Summary

Benefits of technology

The present invention provides a heat-treatment oil composition that has excellent cooling performance, quenching hardness, and quenching distortion. This means that the oil composition can effectively control the cooling and quenching process, resulting in improved performance and quality.

Problems solved by technology

Among these heat treatments, quenching is a treatment for transforming a heated metal material to a predetermined quenched structure by immersing the metal material in a cooling medium, and this quenching makes the treated product very hard.

In the case where the stages are mixedly present, an extremely large temperature difference occurs on the surface of the metal material due to the difference in cooling rate between the vapor film stage and the boiling stage.

The temperature difference generates thermal stress and transformation stress to cause distortion of the metal material.

Therefore, in a heat treatment of a metal material, particularly quenching thereof, it is important to select a heat treatment oil appropriate for the heat treatment conditions, and if the selection is inappropriate, there may be a case where distortion occurs in the metal material and sufficient quenching hardness cannot be obtained.

In general, when the vapor film stage is prolonged, the period of time where the vapor film stage and the boiling stage are mixedly present is also prolonged, and it tends to increase the distortion.

This is because the above-described oils of Class 1 cause large distortion and may increase the hardness excessively for some components, and the above-described No. 2 oil of Class 2 causes small distortion, but provides insufficient hardness.

In this case, there may be a problem that unevenness of hardness and distortion for respective stacked components is caused because unevenness of cooling performance is caused depending on the positions at which the components are set.