Heat treatment technology of steel-grade oil casing

A technology of petroleum casing and steel pipe, which is applied in the field of heat treatment of steel grade petroleum casing, which can solve the problems of insufficient mechanical properties, poor bending effect, and poor hardenability of steel pipes, etc., so as to improve mechanical properties and improve hardenability The effect of reducing the critical cooling rate

Inactive Publication Date: 2018-09-28
LINZHOU FENGBAO PIPE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0013] The purpose of the present invention is to solve the problems of poor hardenability of heat treatment products in the prior art, insufficient mechanical properties of steel pipes, poor protection bending effect, and easy fracture, and proposes a steel grade petroleum casing heat treatment process

Method used

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  • Heat treatment technology of steel-grade oil casing
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Effect test

Embodiment 1

[0046] The invention discloses a heat treatment process for steel-grade petroleum casing. The specific steps are as follows:

[0047] (1) Steel pipe annealing: heat the steel pipe to 700°C, keep it warm and cool it down;

[0048] (2) Steel tube normalizing: heat the cooled steel tube to 750°C, keep it warm and cool it down;

[0049] (3) Steel pipe quenching: heating the cooled steel pipe to 700°C, cooling rapidly after heat preservation to obtain martensite;

[0050] (4) Steel pipe tempering: heat the martensitic steel pipe to 700°C, temper for 1.5 hours, keep warm and then cool.

[0051] The cooling in the step (1)-step (4) is carried out alternately by means of oil cooling and natural cooling in the air.

[0052] The heat preservation time after tempering in the step (4) is 160 minutes, and the temperature during heat preservation is 500°C.

[0053] In the step (4), when the steel pipe is tempered, the furnace is filled with argon.

[0054] The cooling temperature in the...

Embodiment 2

[0056] The invention discloses a heat treatment process for steel-grade petroleum casing. The specific steps are as follows:

[0057] (1) Steel pipe annealing: heat the steel pipe to 700°C, keep it warm and cool it down;

[0058] (2) Steel tube normalizing: heat the cooled steel tube to 750°C, keep it warm and cool it down;

[0059] (3) Steel pipe quenching: heating the cooled steel pipe to 700°C, cooling rapidly after heat preservation to obtain martensite;

[0060] (4) Steel pipe tempering: heat the martensitic steel pipe to 700°C, temper for 1.5 hours, keep warm and then cool.

[0061]The cooling in the step (1)-step (4) is carried out alternately by means of oil cooling and natural cooling in the air.

[0062] In the step (3), 125 g of manganese and boron are added during the first half of the steel pipe quenching, and 175 g of molybdenum are added during the second half of the steel pipe quenching.

[0063] The heat preservation time after tempering in the step (4) is ...

Embodiment 3

[0067] The invention discloses a heat treatment process for steel-grade petroleum casing. The specific steps are as follows:

[0068] (1) Steel pipe annealing: heat the steel pipe to 700°C, keep it warm and cool it down;

[0069] (2) Steel tube normalizing: heat the cooled steel tube to 750°C, keep it warm and cool it down;

[0070] (3) Steel pipe quenching: heating the cooled steel pipe to 700°C, cooling rapidly after heat preservation to obtain martensite;

[0071] (4) Steel pipe tempering: heat the martensitic steel pipe to 700°C, temper for 1.5 hours, keep warm and then cool.

[0072] The cooling in the step (1), step (2) and step (4) adopts two modes of oil cooling and natural cooling in the air alternately, in the step (3), the cooling pipeline is filled with liquid nitrogen, and the liquid nitrogen is used for cooling Way.

[0073] In the step (3), 125 g of manganese is added during the first half of steel pipe quenching, and 175 g of molybdenum is added during the s...

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Abstract

The invention discloses a heat treatment technology of a steel-grade oil casing. The technology comprises the following steps of 1, annealing of a steel pipe, wherein the steel pipe is heated to 650-750 DEG C, subjected to heat preservation and cooled; 2, normalizing of the steel pipe, wherein the cooled steel pipe is heated to 750-850 DEG C, subjected to heat preservation and cooled; 3, quenchingof the steel pipe, wherein the cooled steel pipe is heated to 650-750 DEG C, subjected to heat preservation and then quickly cooled to obtain martensite; 4, tempering of the steel pipe, wherein the martensite steel pipe is heated to 650-750 DEG C, the tempering time is 1.5-2 h, and the steel pipe is subjected to heat preservation and then cooled. Two modes of oil cooling and natural cooling in air are adopted for cooling in the first step, the second step and the fourth step, and in the third step, the pipe is filled with liquid nitrogen, and a liquid nitrogen cooking mode is adopted. According to the heat treatment technology, the hardenability and mechanical properties of the steel pipe can be improved through heat treatment products, the bending protection effect is better, and the steel pipe is not easily broken.

Description

technical field [0001] The invention relates to the field of metal heat treatment technology, in particular to a heat treatment technology for steel-grade oil casing. Background technique [0002] Metal heat treatment is a process that heats, heats, and cools the workpiece in a certain medium, and controls its performance by changing the surface or internal structure of the metal material. [0003] Heat treatment generally has four basic processes of annealing, normalizing, quenching and tempering, commonly known as the "four fires" of metal heat treatment. [0004] 1. Annealing: [0005] Annealing is to heat the workpiece to an appropriate temperature, adopt different holding times according to the material and the size of the workpiece, and then slowly cool it. Get organized. [0006] Second, normalizing: [0007] Normalizing is to heat the workpiece to a suitable temperature and then cool it in the air. The effect of normalizing is similar to that of annealing, but th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/26C21D1/28C21D1/18C21D9/08C21D1/613
CPCC21D1/26C21D1/18C21D1/28C21D1/613C21D9/085C21D2211/008
Inventor 李静敏肖永忠高磊
Owner LINZHOU FENGBAO PIPE
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