A sucker rod steel, a heat treatment process therefor, and a manufacturing method comprising the heat treatment process are provided. The sucker rod steel comprises, in mass percent, the following chemical elements: C: 0.10˜0.20%, Si: 0.40˜0.80%, Mn: 0.20˜0.60%, Mo: 0.36˜0.46%, Cr: 6.15˜7.10%, Al: 0.015˜0.035%, Nb: 0.02˜0.06%, and N: 0.008˜0.015%, with the balance being Fe and other inevitable impurities. The microstructure of the sucker rod steel is tempered martensite and nanoscale precipitates. The grain size is higher than grade 10, the tensile strength is 920˜1320 Mpa, and the AKU2 impact energy is greater than or equal to 180 J.

A sucker rod steel, a heat treatment process therefor, and a manufacturing method comprising the heat treatment process are provided. The sucker rod steel comprises, in mass percent, the following chemical elements: C: 0.10˜0.20%, Si: 0.40˜0.80%, Mn: 0.20˜0.60%, Mo: 0.36˜0.46%, Cr: 6.15˜7.10%, Al: 0.015˜0.035%, Nb: 0.02˜0.06%, and N: 0.008˜0.015%, with the balance being Fe and other inevitable impurities. The microstructure of the sucker rod steel is tempered martensite and nanoscale precipitates. The grain size is higher than grade 10, the tensile strength is 920˜1320 Mpa, and the AKU2 impact energy is greater than or equal to 180 J.

A drill tool capable of coping with a rock drill having high output power and a method for producing the drill tool are described. The drill tool is produced by employing, as a drill tool material, an alloy steel composed of the following chemical components: 0.22 to 0.26 wt % of C, 0.15 to 0.35 wt % of Si, 0.55 to 0.80 wt % of Mn, 2.60 to 3.00 wt % of Ni, 1.00 to 1.50 wt % of Cr, 0.20 to 0.30 wt % of Mo, and Fe and inevitable impurities as the balance. Heat treatment with quenching is performed after carburizing performed by means of oil cooling with cold oil and a tempering temperature set at 400 to 440° C.

A drill tool capable of coping with a rock drill having high output power and a method for producing the drill tool are described. The drill tool is produced by employing, as a drill tool material, an alloy steel composed of the following chemical components: 0.22 to 0.26 wt % of C, 0.15 to 0.35 wt % of Si, 0.55 to 0.80 wt % of Mn, 2.60 to 3.00 wt % of Ni, 1.00 to 1.50 wt % of Cr, 0.20 to 0.30 wt % of Mo, and Fe and inevitable impurities as the balance. Heat treatment with quenching is performed after carburizing performed by means of oil cooling with cold oil and a tempering temperature set at 400 to 440° C.

Provided is a method for executing a quenching method in which an object to be treated that is a quenching target is cooled with a quenching coolant that is a coolant for quenching, in which the object to be treated is moved inside the quenching coolant accumulated in a cooling tank, by a moving device for moving the object to be treated, and at least from when the object to be treated comes into contact with the quenching coolant until a surface of the object to be treated undergoes martensitic transformation, a state in which a relative speed of the object to be treated and the quenching coolant is slower than a moving speed of the object to be treated is maintained.

Provided is a method for executing a quenching method in which an object to be treated that is a quenching target is cooled with a quenching coolant that is a coolant for quenching, in which the object to be treated is moved inside the quenching coolant accumulated in a cooling tank, by a moving device for moving the object to be treated, and at least from when the object to be treated comes into contact with the quenching coolant until a surface of the object to be treated undergoes martensitic transformation, a state in which a relative speed of the object to be treated and the quenching coolant is slower than a moving speed of the object to be treated is maintained.

A steel material and methods for producing the same. The steel material exhibits excellent hydrogen embrittlement resistance in a high-pressure hydrogen gas environment and is, therefore, suitable for use in hydrogen storage tanks, hydrogen line pipes, and the like. The steel material has a specified chemical composition, a tensile strength of 560 MPa or higher, and a fracture toughness value K.sub.IH exhibited by the steel material in a high-pressure hydrogen gas atmosphere is 40 MPa.Math.m.sup.1/2 or higher.

A steel alloy is disclosed that provides a unique combination of strength, toughness, and fatigue life. The steel alloy has the following composition in weight percent:

TABLE-US-00001 C about 0.15 to about 0.30 Mn about 1.7 to about 2.3 Si about 0.7 to about 1.1 Cr about 1.85 to about 2.35 Ni about 0.5 to about 0.9 Mo + ½W about 0.1 to about 0.3 Cu about 0.3 to about 0.7 V + 5/9 × Nb about 0.2 to about 0.5
The balance of the alloy is iron, usual impurities, and residual amounts of other elements added during melting for deoxidizing and/or desulfurizing the alloy. A hardened and tempered steel article made from the alloy is also disclosed.

A vapor film-rupturing agent is provided that is prepared from asphalt as a staring material, so as to have a fraction (x) (% by mass) of a saturated component and a fraction (y) (% by mass) of an asphaltene component based on the total fraction 100% by mass of the saturated component, the asphaltene component, an aromatic component, and a resin component obtained by any one of analysis methods described in the Japan Petroleum Institute Standard and Manuals Testing Method for Petroleum Products JPI-5S-70-10 and the British Standard Test Method IP-469 that satisfy one or more of the following conditions (1) to (3): condition (1): 1.2926×(x)/100−8.113×(y)/100+2.3384≤2.400, condition (2): (y)≥7.0, and condition (3): ((y)/(x))≥0.5. The vapor film-rupturing agent is capable of preparing a thermal treatment oil composition having a high vapor film-rupturing effect with a characteristic number of seconds in the cooling capability test according to JIS K2242 (2012) of 2.50 seconds or less.

A vapor film-rupturing agent is provided that is prepared from asphalt as a staring material, so as to have a fraction (x) (% by mass) of a saturated component and a fraction (y) (% by mass) of an asphaltene component based on the total fraction 100% by mass of the saturated component, the asphaltene component, an aromatic component, and a resin component obtained by any one of analysis methods described in the Japan Petroleum Institute Standard and Manuals Testing Method for Petroleum Products JPI-5S-70-10 and the British Standard Test Method IP-469 that satisfy one or more of the following conditions (1) to (3): condition (1): 1.2926×(x)/100−8.113×(y)/100+2.3384≤2.400, condition (2): (y)≥7.0, and condition (3): ((y)/(x))≥0.5. The vapor film-rupturing agent is capable of preparing a thermal treatment oil composition having a high vapor film-rupturing effect with a characteristic number of seconds in the cooling capability test according to JIS K2242 (2012) of 2.50 seconds or less.