阅读说明：本技术 用微钛处理合金钢提高j k55钢级油井管冲击功的方法 (Method for improving impact power of J K55 steel-grade oil well pipe by treating alloy steel with micro-titanium ) 是由 文玉成 朱海涛 郑贵英 刘金海 李玉柱 丛国元 赵晓林 李凯 武志强 殷占峰 邵 于 2019-11-05 设计创作，主要内容包括：本发明提供一种用微钛处理合金钢提高J K55钢级油井管冲击功的方法,合金管通过0.010％～0.040％的Ti进行处理,包括电炉冶炼、LF炉精炼、管坯连铸、1240℃～1290℃管坯加热、1150℃～1210℃两辊斜轧穿孔、1050℃～1160℃PQF连轧机轧制成荒管、定减径轧制、冷床风机吹风冷却、成型。本发明的有益效果是：油管抗拉强度≥700Mpa、屈服强度≥430Mpa、延伸率≥33％、室温横向冲击功≥50J,组织为铁素体加珠光体；成分设计合理,操作、控制简便,成本低；冲击韧性较好,产品性能满足J55和K55钢级要求,用于石油套管和油管。(The invention provides a method for improving the impact energy of a J K55 steel-grade oil well pipe by alloy steel treated by micro-titanium, wherein the alloy pipe is treated by 0.010-0.040% of Ti, and the method comprises electric furnace smelting, LF furnace refining, pipe blank continuous casting, heating of the pipe blank at 1240-1290 ℃, two-roller inclined rolling and punching at 1150-1210 ℃, rolling of a PQF continuous rolling mill at 1050-1160 ℃ into a pierced billet, fixed reducing rolling, blowing cooling by a cooling bed fan and forming.)

The method for improving the impact energy of a J K55 steel grade oil well pipe by treating alloy steel with micro titanium is characterized in that the oil well pipe comprises, by weight, 0.30-0.40% of C, 0.15-0.40% of Si, 1.20-1.50% of Mn, less than or equal to 0.015% of P, less than or equal to 0.008% of S, less than or equal to 0.20% of Ni, less than or equal to 0.15% of Cr, less than or equal to 0.10% of Mo, less than or equal to 0.20% of Cu, 0.020-0.020% of Al, less than or equal to 0.03% of V, less than or equal to 0.15% of Nb, 0.010-0.040% of Ti and less than or equal to 0.012% of N, and the balance of Fe and inevitable impurity elements, and comprises the steps of smelting in an electric furnace, hot rolling forming, constant diameter reduction rolling and cooling forming, refining in an LF refining furnace, adding a preheating wire in an LF furnace procedure, adjusting the content of titanium alloy elements, wherein the step 1240 and annealing temperature of the annealing zone I comprises the annealing temperature of a continuous casting zone II, the annealing temperature of a continuous casting zone II is 900-1150 ℃, the annealing temperature of a continuous casting zone II temperature of a continuous casting zone I and the annealing temperature of 900-1290 ℃ and the annealing temperature of a heating zone II temperature of a continuous casting temperature of 1150-1250 ℃ of a continuous casting zone II temperature of the annealing temperature.

2. The method for improving the impact work of J K55 steel-grade oil well pipes by treating alloy steel with micro titanium according to claim 1, wherein: the temperature of the hot sizing outlet during the sizing and reducing rolling is 830-900 ℃.

3. The method for improving the impact work of J K55 steel-grade oil well pipes by treating alloy steel with micro titanium according to claim 1, wherein: the continuous casting of the tube blank is that the steel blank is heated to 1240 ℃ to 1290 ℃ in an annular furnace, the temperature of 1150 ℃ to 1210 ℃ is pierced into a blank tube by a two-roller inclined rolling piercer, and the blank tube is rolled into a pierced billet by a 5-frame retained mandrel continuous rolling machine, and the continuous rolling temperature is 1050 ℃ to 1160 ℃.

4. The method for improving the impact work of J K55 steel-grade oil well pipes by treating alloy steel with micro titanium according to claim 1, wherein: the cooling is a cooling bed fan blowing cooling mode.

Technical Field

The invention belongs to the technical field of seamless steel pipe manufacturing in the metallurgical industry, and particularly relates to a method for improving impact power of a J K55 steel-grade oil well pipe by treating alloy steel with kinds of micro-titanium.

Background

The J55 and K55 steel-grade oil well pipes are which are the most commonly used special oil pipes in oil fields, the use amount is large, API 5CT stipulates that J55 and K55-grade steel pipes require P, S to be less than or equal to 0.030 percent in finished products, the yield strength to be more than or equal to 379MPa, the J55 steel-grade tensile strength to be more than or equal to 517MPa, the K55 steel-grade tensile strength to be more than or equal to 655MPa, the elongation to be more than or equal to 24 percent, and no mandatory requirement on the impact performance, along with the development of the oil industry, the drilling working conditions are more complex, the requirement on the oil industry is more rigorous, and the mandatory requirement on the impact performance of J55 and K55.

is widely used for producing 37Mn5 steel of J55 and K55 steel grade seamless steel pipes, contains carbon about 0.37 percent and manganese about 1.5 percent, adopts the steel-making, continuous casting, pipe blank heating, perforating, continuous rolling, sizing and air cooling processes to produce the steel pipes, the yield strength of finished products is about 420MPa, the tensile strength is about 690MPa, the strength requirements of the J55 and K55 steel grade seamless steel pipes are met, but the impact work value is mostly between 15J and 20J, the impact power is low, and the fluctuation range is large.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, and provides manufacturing methods capable of improving the impact toughness of J/K55 steel-grade oil well pipes.

In order to achieve the purpose, the technical scheme adopted by the invention is that kinds of alloy steel are treated by micro titanium to improve the impact energy of a J K55 steel-grade oil well pipe, the oil well pipe comprises, by weight, 0.30-0.40% of C, 0.15-0.40% of Si, 1.20-1.50% of Mn, not more than 0.015% of P, not more than 0.008% of S, not more than 0.20% of Ni, not more than 0.15% of Cr, not more than 0.10% of Mo, not more than 0.20% of Cu, 0.020-0.050% of Al, not more than 0.03% of V, not more than 0.15% of Nb, 0.010-0.040% of Ti, not more than 0.012% of N, and the balance of Fe and inevitable impurity elements, the method comprises smelting in an electric furnace, continuous casting in a hot rolling mode, rolling in a fixed diameter reduction rolling mode, cooling and refining in an LF smelting process, the alloy is carried out, the refining in a refining process of the furnace, the refining process comprises adding titanium wire, adjusting the content of titanium alloy elements in a preheating section, the preheating temperature is 900-1250 ℃, the temperature of the preheating zone is 900 ℃ of a preheating zone II, the preheating zone, the temperature of a preheating zone is 900-1250 ℃, the temperature of a preheating zone, the preheating zone is 900 ℃ of a preheating zone, the temperature is 900-1250 ℃, the temperature is 900 ℃ of a preheating zone, the temperature of a preheating zone.

The temperature of the hot sizing outlet during the sizing and reducing rolling is 830-900 ℃.

The continuous casting of the tube blank is that the steel blank is heated to 1240 ℃ to 1290 ℃ in an annular furnace, the temperature of 1150 ℃ to 1210 ℃ is pierced into a blank tube by a two-roller inclined rolling piercer, and the blank tube is rolled into a pierced billet by a 5-frame retained mandrel continuous rolling machine, and the continuous rolling temperature is 1050 ℃ to 1160 ℃.

The cooling is a cooling bed fan blowing cooling mode.

C, carbon is a carbide forming element, the strength of the steel is improved through the effects of solid solution strengthening and precipitation strengthening, and as the carbon content in the steel is increased, the yield strength and the tensile strength are increased, but the plasticity and the impact property are reduced. According to API 5CT standard requirements and K55 steel-grade oil well pipe test results, the carbon content in the chemical composition of the steel is determined to be 0.30-0.40%.

Si: silicon is a commonly used deoxidizer, which can improve the strength of solid solution of steel and remarkably improve the elastic limit, yield limit and yield ratio of steel in alloy steel, but the addition of a large amount of silicon can reduce the toughness of steel, and therefore, the component range of the silicon element is controlled to be 0.15-0.40%.

Mn has a deoxidizing effect, has a strong solid solution strengthening effect on ferrite and austenite, and can compensate for the loss yield strength caused by the reduction of carbon content, but when the manganese content is too high, the toughness of steel is reduced, the center segregation tendency of a pipe blank is increased, and the performance uniformity of the steel is influenced, wherein the content of the manganese in an -type oil well pipe is 1.20-1.50%.

Ti: titanium is a strong carbon and nitride forming element, and can be combined with N, C to form stable nitride and carbide, thereby preventing austenite grains from growing, refining the grains and improving the strength and toughness of the steel. The titanium content is too low to exert the function, and the excessive titanium content is easy to form coarse Ti (C, N) inclusions to destroy the toughness of the steel, and the proper range is 0.010-0.040%.

Al: aluminum is a common deoxidizer, has the effects of refining grains and improving the oxidation resistance of steel, can reduce the strong plasticity of the steel when the content is higher, and is strictly controlled as follows: 0.020-0.050%.

N is present in the steel in the form of nitride, the plasticity and impact toughness of the steel are deteriorated when the nitrogen content is too high, and the small amount of nitride can play a role in refining crystal grains, and the content of the nitride is controlled to be less than or equal to 0.012 percent.

The invention has the beneficial effects that: the alloy smelting operation is simple and convenient, and the production cost is lower; by adopting a reasonable tube blank heating and hot rolling production process, the room-temperature structure of the steel tube is a ferrite and pearlite structure, the crystal grains are fine and uniform, the grain size reaches more than 7.5 grade, the TN second-phase precipitate is uniform and fine in distribution, the product performance completely meets the requirements of API 5CT standard J55 and K55 steel grade, and the impact toughness reaches more than 50J at room-temperature transverse Akv.

Detailed Description

The invention is further described with reference to the following examples.

The invention relates to a method for improving impact energy of J K55 steel-grade oil well pipes by treating alloy steel with kinds of micro titanium, which comprises the following components, by weight, 0.30-0.40% of C, 0.15-0.40% of Si, 1.20-1.50% of Mn, less than or equal to 0.015% of P, less than or equal to 0.008% of S, less than or equal to 0.20% of Ni, less than or equal to 0.15% of Cr, less than or equal to 0.10% of Mo, less than or equal to 0.20% of Cu, 0.020-0.050% of Al, less than or equal to 0.03% of V, less than or equal to 0.15% of Nb, 0.010-0.040% of Ti and less than or equal to 0.012% of N, and the balance of Fe and inevitable impurity elements, wherein the method comprises the steps of smelting in an electric furnace, hot rolling, constant diameter reduction rolling and cooling forming, refining in an LF furnace, adding titanium wires in a refining process of a preheating furnace refining process, adjusting alloy element content, wherein the hot rolling forming comprises a heating section in an annular furnace, a continuous casting section, a preheating temperature of a preheating section I is 900-1250 ℃, a billet II, a preheating section temperature is 0 ℃ and a temperature of a continuous casting temperature is 900-1250 ℃, a temperature is a temperature of a soaking section II, wherein the temperature of a soaking section I is 0-1250 ℃, and.

The temperature of the hot sizing outlet during the sizing and reducing rolling is 830-900 ℃.

The continuous casting of the tube blank is that the steel blank is heated to 1240 ℃ to 1290 ℃ in an annular furnace, the temperature of 1150 ℃ to 1210 ℃ is pierced into a blank tube by a two-roller inclined rolling piercer, and the blank tube is rolled into a pierced billet by a 5-frame retained mandrel continuous rolling machine, and the continuous rolling temperature is 1050 ℃ to 1160 ℃.

The cooling is a cooling bed fan blowing cooling mode.

C, carbon is a carbide forming element, the strength of the steel is improved through the effects of solid solution strengthening and precipitation strengthening, and as the carbon content in the steel is increased, the yield strength and the tensile strength are increased, but the plasticity and the impact property are reduced. According to API 5CT standard requirements and K55 steel-grade oil well pipe test results, the carbon content in the chemical composition of the steel is determined to be 0.30-0.40%.

Si: silicon is a commonly used deoxidizer, which can improve the strength of solid solution of steel and remarkably improve the elastic limit, yield limit and yield ratio of steel in alloy steel, but the addition of a large amount of silicon can reduce the toughness of steel, and therefore, the component range of the silicon element is controlled to be 0.15-0.40%.

Mn has a deoxidizing effect, has a strong solid solution strengthening effect on ferrite and austenite, and can compensate for the loss yield strength caused by the reduction of carbon content, but when the manganese content is too high, the toughness of steel is reduced, the center segregation tendency of a pipe blank is increased, and the performance uniformity of the steel is influenced, wherein the content of the manganese in an -type oil well pipe is 1.20-1.50%.

Ti: titanium is a strong carbon and nitride forming element, and can be combined with N, C to form stable nitride and carbide, thereby preventing austenite grains from growing, refining the grains and improving the strength and toughness of the steel. The titanium content is too low to exert the function, and the excessive titanium content is easy to form coarse Ti (C, N) inclusions to destroy the toughness of the steel, and the proper range is 0.010-0.040%.

Al: aluminum is a common deoxidizer, has the effects of refining grains and improving the oxidation resistance of steel, can reduce the strong plasticity of the steel when the content is higher, and is strictly controlled as follows: 0.020-0.050%.

N is present in the steel in the form of nitride, the plasticity and impact toughness of the steel are deteriorated when the nitrogen content is too high, and the small amount of nitride can play a role in refining crystal grains, and the content of the nitride is controlled to be less than or equal to 0.012 percent.