Heat-treatment oil composition

Abstract

Provided is a heat-treatment oil composition that makes it possible to suppress quenching distortion and distortion variation and to achieve improved quenching hardness. A heat-treatment oil composition that includes a base oil (A) and a vapor film rupturing agent (B). The heat-treatment oil composition makes it such that, on a cooling curve obtained in accordance with the cooling performance test method in HS K2242:2012, the time in seconds to 300° C., e.g., the cooling time from 800° C. to 300° C., is at least 6.5 seconds but less than 10 seconds. Component (B) includes a petroleum resin.

1 . A heat-treatment oil composition, comprising:
 a base oil; and   a vapor film rupturing agent comprising a petroleum resin,   wherein, on a cooling curve obtained in accordance with a cooling performance test method of JIS K2242:2012, a number of seconds to 300° C., which is a cooling time from 800° C. to 300° C., is 6.5 seconds or more but less than 10 seconds.   
     
     
         2 . The heat-treatment oil composition according to  claim 1 , wherein a characteristic number of seconds obtained from the cooling curve is 1 second or more. 
     
     
         3 . The heat-treatment oil composition according to  claim 1 , further comprising:
 a metal-based detergent dispersant.   
     
     
         4 . The heat-treatment oil composition according to  claim 3 , wherein metal-based detergent dispersant is present in a range of from 0.01 to 10% by mass based on a total amount of the composition. 
     
     
         5 . The heat-treatment oil composition according to  claim 1 , wherein the characteristic number of seconds obtained from the cooling curve is 2.5 seconds or less. 
     
     
         6 . The heat-treatment oil composition according to  claim 1 , wherein the petroleum resin has a softening point of from 40 to 150° C. 
     
     
         7 . The heat-treatment oil composition according to  claim 1 , wherein the petroleum resin has a number-average molecular weight (Mn) of from 200 to 5,000. 
     
     
         8 . The heat-treatment oil composition according to  claim 1 , wherein the petroleum resin is a resin obtained by polymerizing or copolymerizing at least one unsaturated compound selected from the group consisting of an aliphatic olefin comprising from 4 to 10 carbon atoms, an aliphatic diolefin, and an aromatic compound having comprising an olefinic unsaturated bond and 8 or more carbon atoms. 
     
     
         9 . The heat-treatment oil composition according to  claim 1 , wherein the petroleum resin is at least one selected from the group consisting of an aliphatic petroleum resin, an aromatic petroleum resin, an aliphatic-aromatic copolymerization-based petroleum resin, a dicyclopentadiene-based petroleum resin, a dicyclopentadiene-aromatic copolymerization-based petroleum resin, and a hydrogenated petroleum resin and modified petroleum resin thereof. 
     
     
         10 . The heat-treatment oil composition according to  claim 1 , having a kinetic viscosity at 40° C. of from 10 to 280 mm 2 /s. 
     
     
         11 . The heat-treatment oil composition according to  claim 1 , wherein the base oil comprises a low-viscosity base oil having a kinetic viscosity at 40° C. of 1 mm 2 /s or more but less than 85 mm 2 /s and a high-viscosity base oil having a kinetic viscosity at 40° C. of from 85 to 550 mm 2 /s. 
     
     
         12 . The heat-treatment oil composition according to  claim 1 , wherein the petroleum resin is present in a range of from 0.1 to 90% by mass based on a total amount of the heat-treatment oil composition. 
     
     
         13 . The heat-treatment oil composition according to  claim 1 , wherein the base oil is present in a range of from 10 to 99.9% by mass based on a total amount of the heat-treatment oil composition. 
     
     
         14 . A method for quenching a metal material, the method comprising:
 treating the metal material with the heat-treatment oil composition according to  claim 1 .   
     
     
         15 . A method for producing the heat-treatment oil composition according to  claim 1 , the method comprising:
 mixing the base oil and the vapor film rupturing agent.