High-strength toughness air-cooled drill steel and production method thereof

Abstract

The invention discloses steel for high-tenacity air cooling drill tool and a production method thereof.The steel is prepared from, by weight, 0.1-0.40% of C, 0.7-1.3% of Si, 1.7-2.5% of Mn, 0.7-2.0% of Cr, 0.1-0.3% of Mo, 0.04-0.2% of V, 0.02-0.6% of Al, 0.001-0.08% of Sc, or 0.001-0.02% of other rare earth elements Ce and La, and the balance Fe, wherein Sc is from intermediate alloy of Al and Sc, and the weight percent of the Sc in the intermediate alloy is 1.5-4%.According to the steel, the tenacity and plasticity can be improved, the drilling tool and other components have the best toughness cooperation, the service fatigue life of the drilling tool is remarkably prolonged, and the steel is not likely to deform and low in cost.

Description

technical field [0001] The invention relates to the technical field of materials, in particular to a high-strength toughness air-cooled drill steel and a production method of the high-strength toughness air-cooled drill steel. Background technique [0002] Rock drilling tools are slender rods, and direct liquid quenching will easily lead to severe deformation and make them unusable. Therefore, heavy-duty drill rods are made of low-carbon alloy steel, and then carburized, air-cooled, quenched, and tempered at low temperature to reduce quenching deformation. Martensite is obtained in the surface carburized layer, and martensite plus bainite is obtained in the center as the final use structure. However, most of these steels currently use low-carbon Ni-Cr steels, which have the advantages of stable performance, excellent strength and toughness, low notch sensitivity, and gentle surface carbon concentration gradient after carburizing. However, a higher Ni content leads to a sign...

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Problems solved by technology

However, the higher Ni content leads to a significant increase in material cost, and at the same time, the surface microstructure of this type of material is coarser after carburizing, which is not conducive to improving the fatigue life of the drill rod

For this reason, some people use low-cost Si-Mn-Mo series low-medium carbon bainitic steel to replace Ni-Cr series steel to reduce costs. After carburizing, this type of steel can obtain high strength under appropriate air cooling conditions. Toughness, its air-cooling hardenability is good, and uniform bainite structure can be obtained on the entire cross-section, but Si-Mn-Mo-Cr air-cooled bainite steel is prone to grain boundary oxidation during carburization, and there is also the first This will damage the fatigue strength and life of the drill tool, and it is also not conducive to the further improvement of the strength and toughness of the drill tool