Method for producing 42CrMo steel seamless steel tube

Abstract

The invention relates to a method for producing 42CrMo steel seamless steel tubes, belonging to the field of metallurgy. The invention solves the technical problem of providing a method for producing 42CrMo steel seamless steel tubes, which can produce and obtain the seamless steel tube with total cross-section and even hardness. The method for producing the 42CrMo steel seamless steel tubes comprises the following steps: smelting molten steel, casting blanks, hot rolling and heat treating, wherein the heat treating step comprises the following steps: a. quenching a hot-rolled steel tube and heating to 800-900 DEG C; then cooling by water, wherein the outer surface of the steel tube is cooled in the mode of spraying, the inner surface of the steel tube is cooled in the mode of inner axialflow, the inner axial flow is firstly carried out when cooling, then the outer surface of the steel tube is sprayed, the inner axial flow stops when cooling ends, and then the steel tube outer surface spraying stops; and b. tempering after the steel tube is cooled to room temperature, wherein tempering and heating temperature is 520-620 DEG C.

Description

technical field [0001] The invention relates to a method for producing 42CrMo steel seamless steel pipes, belonging to the field of metallurgy. Background technique [0002] The stator tube is a seamless steel tube used to process screw drilling tools for oil wells. It is generally made of 42CrMo steel. The chemical composition of 42CrMo steel is: C 0.38-0.45%, Mn 0.50-0.80%, Si 0.17-0.37 %, Cr0.90~1.20%, Mo 0.15~0.25%, P≤0.025%, S≤0.025%, and the balance is Fe and unavoidable impurities. 42CrMo steel is generally heat treated in a periodic heat treatment furnace, and there is no report on heat treatment on a step-by-step continuous heat treatment line. The continuous heat treatment production line is generally composed of quenching furnace, quenching device and tempering furnace. The quenching device generally uses water quenching, which has the characteristics of high output and low cost. There are two problems to be solved in the production of 42CrMo steel on the contin...

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Problems solved by technology

42CrMo steel is generally heat treated in a periodic heat treatment furnace, and there is no report on heat treatment on a step-by-step continuous heat treatment line

There are two problems to be solved in the production of 42CrMo steel on the continuous heat treatment line: first, the stator tube requires a very narrow hardness range for the full section of the steel tube, and the hardness at any point of the full wall thickness of the steel tube is 277 to 310HB, which requires the steel tube to be completely hardened And uniform tempering; the second is that 42CrMo steel has high carbon content, and it is easy to crack when using water quenching. Usually, water-based quenching liquid is used for quenching, water quenching air cooling or oil quenching, but water-based quenching liquid is expensive and costly, and oil quenching is expensive. Flammable, unsafe, water quenching and air cooling require a long cooling time, not suitable for continuous heat treatment lines

[0006] At present, there is no relevant report on the production of seamless steel pipes for stator pipes by continuous heat treatment.

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