The steel material according to the present disclosure has a chemical composition consisting of, in mass %, C: 0.20 to 0.35%, Si: 0.05 to 1.00%, Mn: 0.01 to 1.00%, P: 0.025% or less, S: 0.0100% or less, Al: 0.005 to 0.100%, Cr 0.25 to 0.80%, Mo: 0.20 to 2.00%, Ti: 0.002 to 0.050%, B: 0.0001 to 0.0050%, N: 0.0020 to 0.0100% and O: 0.0100% or less, with the balance being Fe and impurities, and satisfying Formula (1). A number density of precipitates having an equivalent circular diameter of 400 nm or more is 0.150 particles/μm.sup.2 or less. The yield strength is within a range of 655 to 965 MPa. A dislocation density ρ is 7.0×10.sup.14 m.sup.−2 or less.

5×Cr—Mo-2×(V+Ti)≤3.00  (1)

In some examples, an apparatus includes a pallet supporting a plurality of workpieces, the pallet including through-holes structured to pass a quenching fluid. In some examples, the apparatus further includes a reservoir of quenching fluid configured to provide the quenching fluid, and a plurality of upturned wall portions extending from the pallet and substantially surrounding the exteriors of the plurality of workpieces. The plurality of upturned wall portions may be located in relative orientation to the plurality of workpieces to regulate heat transfer coefficients of the plurality of workpieces during a quenching operation.

In some examples, an apparatus includes a pallet supporting a plurality of workpieces, the pallet including through-holes structured to pass a quenching fluid. In some examples, the apparatus further includes a reservoir of quenching fluid configured to provide the quenching fluid, and a plurality of upturned wall portions extending from the pallet and substantially surrounding the exteriors of the plurality of workpieces. The plurality of upturned wall portions may be located in relative orientation to the plurality of workpieces to regulate heat transfer coefficients of the plurality of workpieces during a quenching operation.

An intensive quenching (IQ) apparatus and method of quenching heated parts is provided. The IQ apparatus includes a chute for placing parts into a tank including liquid quenchant. The parts fall through the quenchant in the chute and are received by a conveyor belt. The parts are then transported on the conveyor through an inner channel of a conduit. An agitation rate of the quenchant in the inner channel is increased by an agitator.

An intensive quenching (IQ) apparatus and method of quenching heated parts is provided. The IQ apparatus includes a chute for placing parts into a tank including liquid quenchant. The parts fall through the quenchant in the chute and are received by a conveyor belt. The parts are then transported on the conveyor through an inner channel of a conduit. An agitation rate of the quenchant in the inner channel is increased by an agitator.

An on-line intelligent control method for the cooling characteristics of a quenching liquid in heat treatment production includes the steps of: step 1: subjecting a workpiece to thermal insulation; step 2: measuring the cooling characteristics and the heat transfer coefficient of a quenching liquid followed by correction; step 3: starting cooling; step 4: then changing the internal circulation rate; and step 5: removing the workpiece. This scheme can effectively avoid the problem that the cooling of a workpiece in industrial production deviates from the ideal cooling characteristics of a quenching liquid obtained in a laboratory.

An on-line intelligent control method for the cooling characteristics of a quenching liquid in heat treatment production includes the steps of: step 1: subjecting a workpiece to thermal insulation; step 2: measuring the cooling characteristics and the heat transfer coefficient of a quenching liquid followed by correction; step 3: starting cooling; step 4: then changing the internal circulation rate; and step 5: removing the workpiece. This scheme can effectively avoid the problem that the cooling of a workpiece in industrial production deviates from the ideal cooling characteristics of a quenching liquid obtained in a laboratory.

Iron-based alloys and articles in strips, sheets, workpieces and the like are converted into high strength steel with a minimum of cost, time and effort, including producing dual phase materials. This is achievable by extremely rapid micro-treating of low, medium, and high carbon iron-based alloys and articles by rapid heating and rapid cooling at least a portion of the alloy/article. This heating step involves nearly immediately heating the iron-based alloy to a selected temperature above its austenite conversion temperature. Then, the alloy is immediately quenched, also at an extremely fast rate, on at least a portion of the iron-based alloy in a quenching unit adjacent the heating unit. This procedure forms high strength alloy in a desired area, depending upon where the treatment was performed.

Iron-based alloys and articles in strips, sheets, workpieces and the like are converted into high strength steel with a minimum of cost, time and effort, including producing dual phase materials. This is achievable by extremely rapid micro-treating of low, medium, and high carbon iron-based alloys and articles by rapid heating and rapid cooling at least a portion of the alloy/article. This heating step involves nearly immediately heating the iron-based alloy to a selected temperature above its austenite conversion temperature. Then, the alloy is immediately quenched, also at an extremely fast rate, on at least a portion of the iron-based alloy in a quenching unit adjacent the heating unit. This procedure forms high strength alloy in a desired area, depending upon where the treatment was performed.

The method for quench seasoning multiple units of iron/steel cookware includes the steps of: preheating each cookware unit to a temperature above the smoke point of oil in an oil bath; rapidly plunging the preheated cookware units into the oil bath to completely submerge the cookware units and quickly enough to ensure the temperature of the cookware units remain above oil smoke point; controlling the temperature of the oil bath to a ensure that the temperature of the oil bath does not reach a temperature close to oil smoke point, for example, a temperature within 20 degrees below smoke point, and retrieving the cookware units from the oil bath.