Heat treatment oil composition

Abstract

A heat treatment oil composition is provided that is capable of reducing the fluctuation in cooling capability among components subjected to mass quenching while retaining a cooling capability equivalent to the No. 1 oil of Class 2 of JIS K2242:2012 in a heat treatment of a metal material, such as quenching, and is capable of suppressing deterioration in cooling capability thereof with the lapse of time under repetition of the heat treatment. The heat treatment oil composition contains (A) a base oil and (B) at least one selected from a petroleum resin and/or a derivative of a petroleum resin, and has a characteristic time obtained from a cooling curve obtained according to the cooling capability test method of JIS K2242:2012 of 1.00 second or less and a 300° C. number of second, which is a cooling time from 800° C. to 300° C. in the cooling curve, of 6.00 seconds or more and 14.50 seconds or less.

1 . A heat treatment oil composition, comprising:
 (A) a base oil; and   (B) at least one selected from the group consisting of a petroleum resin, a derivative of a petroleum resin, and a mixture thereof,   wherein the heat treatment oil composition has a characteristic time obtained from a cooling curve obtained according to the cooling capability test method of JIS K2242:2012 of 1.00 second or less, and a 300° C. number of second, which is a cooling time from 800° C. to 300° C. in the cooling curve, of 6.00 seconds or more and 14.50 seconds or less.   
     
     
         2 . The heat treatment oil composition according to  claim 1 , wherein the petroleum resin, the derivative of a petroleum resin, or both, has a softening point measured by the ring and ball method of JIS K2207:2006 of 40° C. or more. 
     
     
         3 . The heat treatment oil composition according to  claim 2 , wherein the petroleum resin, the derivative of a petroleum resin, or both, has a softening point measured by the ring and ball method of JIS K2207:2006 of 60° C. or more and 150° C. or less. 
     
     
         4 . The heat treatment oil composition according to  claim 1 , wherein the base oil as the component (A) has a 40° C. kinetic viscosity of from 40 to 500 mm 2 /s. 
     
     
         5 . The heat treatment oil composition according to  claim 1 , comprising:
 from 10 to 99.9% by mass of the base oil; and   from 0.1 to 90% by mass of the petroleum resin, the derivative of a petroleum resin, or both,   based on a total mass of the heat treatment oil composition.   
     
     
         6 . The heat treatment oil composition according to  claim 1 , wherein the heat treatment oil composition has a 100° C. kinetic viscosity of from 10 to 30 mm 2 /s.