阅读说明：本技术 一种提高高钢级抗硫钻杆焊区抗硫性能的热处理方法 (Heat treatment method for improving sulfur resistance of high-steel-grade sulfur-resistant drill pipe welding area ) 是由 欧阳志英 舒志强 余世杰 陈猛 朱威 于 2021-08-19 设计创作，主要内容包括：本发明公开了一种提高高钢级抗硫钻杆焊区抗硫性能的热处理方法,钻杆焊区由120S钢级或125S钢级抗硫管体和120S钢级抗硫钻杆接头经惯性摩擦焊接形成,钻杆焊区热处理包括第一次淬火、第二次淬火、第三次淬火及回火热处理四个步骤。第一次淬火时,淬火加热温度为830～860℃,热影响范围55～65mm,第二次淬火时；淬火加热温度为800～830℃,热影响范围35～55mm；第三次淬火时,淬火加热温度750～800℃,热影响范围10～35mm；回火时,回火加热温度670～710℃,回火热影响区范围75～95mm。本发明热处理后,可使钻杆焊区得到弥散均匀的回火索氏体和铁素体,且铁素体占比不低于25％,将显著提高120S或125S高钢级抗硫钻杆焊区抗硫化氢应力腐蚀性能,其抗硫化氢腐蚀试验通过率为从30％提高到高于95％。(The invention discloses a heat treatment method for improving the sulfur resistance of a high-steel-grade sulfur-resistant drill pipe welding area, wherein the drill pipe welding area is formed by inertia friction welding of a 120S steel-grade or 125S steel-grade sulfur-resistant pipe body and a 120S steel-grade sulfur-resistant drill pipe joint, and the heat treatment of the drill pipe welding area comprises four steps of primary quenching, secondary quenching, tertiary quenching and tempering heat treatment. The quenching heating temperature is 830-860 ℃ during the first quenching, the heat influence range is 55-65 mm during the second quenching; the quenching heating temperature is 800-830 ℃, and the thermal influence range is 35-55 mm; during the third quenching, the quenching heating temperature is 750-800 ℃, and the heat influence range is 10-35 mm; when tempering, the tempering heating temperature is 670-710 ℃, and the range of the tempering heat affected zone is 75-95 mm. After the heat treatment, the invention can lead the welding area of the drill rod to obtain evenly dispersed tempered sorbite and ferrite, the ratio of the ferrite is not less than 25 percent, the hydrogen sulfide stress corrosion resistance of the welding area of the 120S or 125S high-grade sulfur-resistant drill rod is obviously improved, and the passing rate of the hydrogen sulfide corrosion resistance test is improved from 30 percent to more than 95 percent.)

1. A heat treatment method for improving the sulfur resistance of a high-steel-grade sulfur-resistant drill pipe welding area is characterized in that the drill pipe welding area is formed by inertia friction welding of a 120S steel-grade or 125S steel-grade sulfur-resistant pipe body and a 120S steel-grade sulfur-resistant joint, the heat treatment of the drill pipe welding area comprises four treatment steps of primary quenching treatment, secondary quenching treatment, tertiary quenching treatment and tempering treatment, and the heat treatment method is characterized by comprising the following specific heat treatment processes:

the first quenching treatment step specifically comprises the following steps: (1) selecting a quenching heating coil with the width of 45mm, and conveying the welding area of the drill rod to the position of the quenching heating coil, wherein the center of the quenching heating coil is aligned with a welding line; (2) raising the temperature of the welding area to 830-860 ℃ in 50-70 s, and preserving the temperature for 100-120 s; (3) the quenching cooling adopts a water-soluble PAG medium with the external spraying concentration of 12.5 percent and compressed air with the internal spraying, and the range of a heat affected zone of the first quenching is 55-65 mm;

step two, the secondary quenching treatment step specifically comprises: (1) selecting a quenching heating coil with the width of 30mm, and conveying the welding area of the drill rod to the position of the quenching heating coil, wherein the center of the quenching heating coil is aligned to the welding line; (2) raising the temperature of the welding area to 800-830 ℃ in 40-60 s, and preserving the heat for 90-110 s; (3) the quenching cooling adopts a water-soluble PAG medium with 12.5% of external spraying concentration and compressed air internal spraying, and the range of a heat affected zone of the second quenching is 35-55 mm;

step three, the third quenching treatment step specifically comprises the following steps: (1) selecting a quenching heating coil with the width of 15mm, and conveying the welding area of the drill rod to the position of the quenching heating coil, wherein the center of the quenching heating coil is aligned with a welding line; (2) raising the temperature of the welding area to 750-800 ℃ in 30-50 s, and preserving the heat for 80-100 s; (3) the quenching cooling adopts water-soluble PAG medium with 12.5% of external spraying concentration and compressed air internal spraying, and the range of a heat affected zone of the third quenching is 10-35 mm;

step four, the tempering treatment step specifically comprises: (1) a tempering heating coil with the width of 75mm is selected, the welding area of the drill rod is sent to the position of the tempering heating coil, and the center of the tempering heating coil is aligned with a welding line; (2) raising the temperature of the welding area to 670-710 ℃ in 60-80 s, and preserving the heat for 220-240 s; (3) cooling the air to room temperature; the range of the tempering heat affected zone is 75-95 mm.

2. The heat treatment method for improving the sulfur resistance of the weld zone of the high-steel-grade sulfur-resistant drill pipe as claimed in claim 1, wherein the 120S steel-grade sulfur-resistant drill pipe body, the 125S steel-grade sulfur-resistant drill pipe body and the 120S sulfur-resistant joint are made of the same material, and the main alloy elements of the material comprise: 0.25-0.30% of C, 0.35-0.50% of Mn, 1.25-1.55% of Cr, 0.50-0.95% of Mo, 0.10-0.50% of V, 0.03-0.25% of Nb, 0.025-0.75% of Cu, less than or equal to 0.005% of P, less than or equal to 0.003% of S, less than or equal to 0.03% of Al, and the balance of Fe.

3. The heat treatment method for improving the sulfur resistance of the weld zone of the high-steel-grade sulfur-resistant drill pipe as claimed in claim 2, wherein the yield strength of the 120S-steel-grade sulfur-resistant pipe body is not less than 827 MPa; the yield strength of the 125S steel grade sulfur-resistant pipe body is not less than 862MPa, and the yield strength of the 120S steel grade sulfur-resistant pipe joint is not less than 827 MPa.

4. The heat treatment method for improving the sulfur resistance of the weld zone of the high-steel-grade sulfur-resistant drill rod as claimed in any one of claims 1 to 3, wherein the first quenching temperature is higher than AC3 temperature, and the range of the heat affected zone of the first quenching is 55-65 mm; the second quenching temperature is slightly lower than the AC3 temperature, and the range of a heat affected zone of the second quenching is 35-55 mm; the third quenching temperature is between the second quenching temperature and the AC1 temperature, and the range of a heat affected zone of the third quenching is 10-35 mm.

Technical Field

The invention belongs to the technical field of petroleum drill pipes, and relates to a heat treatment method for improving the sulfur resistance of a high-steel-grade sulfur-resistant drill pipe welding area.

Background

In the exploration and exploitation process of sulfur-containing oil and gas resources, hydrogen sulfide stress corrosion cracking (SSC) is easily generated by adopting a conventional drill rod, and related standards require that the risk caused by SSC is reduced by adopting a drill rod with excellent hydrogen sulfide stress corrosion resistance. At present, 105SS sulfur-resistant drill pipes are commonly used in the market, but the drill pipes have the defects of insufficient bearing capacity and low safety factor in deep wells (such as well depth exceeding 6000 meters), and in recent years, high-steel-grade sulfur-resistant drill pipe products such as 120S and 125S become the market demand.

The drill rod is formed by a drill rod pipe body and a drill rod joint through friction welding, and for a 105SS drill rod, the pipe body and the joint are required to be subjected to SSC performance evaluation under certain stress according to a uniaxial tensile test (method A, solution A) in NACE TM0177 test method for sulfide stress cracking and stress corrosion resistance of metal in hydrogen sulfide environment, wherein the loading stress of the pipe body is 85% of SMYS, the loading stress of the joint is 65% of SMYS, and no requirement is imposed on the SSC performance of a welding seam.

In recent years, international standards have put forth specific requirements on hydrogen sulfide stress corrosion resistance in the weld zone of sulfur-resistant drill pipe, for example, API 5DP-2020 standard requires that welds be subjected to uniaxial tensile tests (method a, solution D) as specified in NACE TM0177 standard, with a loading stress of 80% SMYS; the ISO11961-2018 standard requires that the weld be subjected to uniaxial tensile testing (method A, solution A) as specified in NACE TM0177 standard with a loading stress of 60% SMYS. For 120S and 125S high-steel-grade sulfur-resistant drill pipes, no relevant international standard exists at present, and internal control standards are implemented.

The weld joint is subjected to heat treatment by adopting a conventional heat treatment method, namely high-temperature quenching and tempering (often called quenching and tempering), the hardness value difference of a heat affected zone of the weld joint is large, the distribution is uneven, particularly, the metallographic structure of the weld joint is a tempered sorbite, the hardness is often very high, and the sulfide stress corrosion resistance is poor. For example, for a 120S sulfur-resistant drill rod, conventional quenching and tempering treatment is adopted, the hardness on a welding line is as high as 35HRC, the hardness deviation value of a welding line heat affected zone exceeds 10HRC, the hydrogen sulfide corrosion resistance test passing rate is between 0 and 30 percent and is far lower than the international standard requirement.

Disclosure of Invention

The invention provides a heat treatment method for improving a high-steel-grade sulfur-resistant drill pipe body and a joint welding area, which reduces the hardness value of the welding area, reduces the deviation of the hardness value, obviously improves the hydrogen sulfide stress corrosion resistance (SSC) of the welding area of a 120S or 125S high-steel-grade sulfur-resistant drill pipe, increases the hydrogen diffusion coefficient and avoids the loss of the welding area of the drill pipe caused by sulfide stress corrosion cracking.

In order to achieve the purpose, the invention provides the following technical scheme:

a heat treatment method for improving the sulfur resistance of a high-steel-grade sulfur-resistant drill pipe welding area is characterized in that the drill pipe welding area is formed by inertia friction welding of a 120S steel-grade or 125S steel-grade sulfur-resistant pipe body and a 120S steel-grade sulfur-resistant joint, the heat treatment of the drill pipe welding area comprises four treatment steps of primary quenching treatment, secondary quenching treatment, tertiary quenching treatment and tempering treatment, and the specific heat treatment process is as follows:

the first quenching treatment step specifically comprises the following steps: (1) selecting a quenching heating coil with the width of 45mm, and conveying the welding area of the drill rod to the position of the quenching heating coil, wherein the center of the quenching heating coil is aligned with a welding line; (2) raising the temperature of the welding area to 830-860 ℃ in 50-70 s, and preserving the temperature for 100-120 s; (3) the quenching cooling adopts a water-soluble PAG medium with the external spraying concentration of 12.5 percent and compressed air with the internal spraying, and the range of a heat affected zone of the first quenching is 55-65 mm; compressed air is sprayed in the inner part, and the time of spraying in the outer part exceeds 50 s.

Step two, the secondary quenching treatment step specifically comprises: (1) selecting a quenching heating coil with the width of 30mm, and conveying the welding area of the drill rod to the position of the quenching heating coil, wherein the center of the quenching heating coil is aligned to the welding line; (2) raising the temperature of the welding area to 800-830 ℃ in 40-60 s, and preserving the heat for 90-110 s; (3) the quenching cooling adopts a water-soluble PAG medium with 12.5% of external spraying concentration and compressed air internal spraying, and the range of a heat affected zone of the second quenching is 35-55 mm;

step three, the third quenching treatment step specifically comprises the following steps: (1) selecting a quenching heating coil with the width of 15mm, and conveying the welding area of the drill rod to the position of the quenching heating coil, wherein the center of the quenching heating coil is aligned with a welding line; (2) raising the temperature of the welding area to 750-800 ℃ in 30-50 s, and preserving the heat for 80-100 s; (3) the quenching cooling adopts water-soluble PAG medium with 12.5% of external spraying concentration and compressed air internal spraying, and the range of a heat affected zone of the third quenching is 10-35 mm;

step four, the tempering treatment step specifically comprises: (1) a tempering heating coil with the width of 75mm is selected, the welding area of the drill rod is sent to the position of the tempering heating coil, and the center of the tempering heating coil is aligned with a welding line; (2) raising the temperature of the welding area to 670-710 ℃ in 60-80 s, and preserving the heat for 220-240 s; (3) cooling the air to room temperature; the range of the tempering heat affected zone is 75-95 mm.

The 120S steel grade, 125S steel grade sulfur-resistant drill pipe body and the 120S sulfur-resistant joint are made of the same material, and the material mainly comprises the following alloy elements: 0.25-0.30% of C, 0.35-0.50% of Mn, 1.25-1.55% of Cr, 0.50-0.95% of Mo, 0.10-0.50% of V, 0.03-0.25% of Nb, 0.025-0.75% of Cu, less than or equal to 0.005% of P, less than or equal to 0.003% of S, less than or equal to 0.03% of Al, and the balance of Fe.

The yield strength of the 120S steel grade sulfur-resistant pipe body is not less than 827 MPa; the yield strength of the 125S steel grade sulfur-resistant pipe body is not less than 862MPa, and the yield strength of the 120S steel grade sulfur-resistant pipe joint is not less than 827 MPa. The sulfur resistance of the material can meet the requirement of no fracture within 720 hours under the specified loading stress.

Compared with the prior art, the invention has the following beneficial effects:

1. when the welding areas of 120S and 125S high-steel-grade sulfur-resistant drill rods are subjected to heat treatment, a three-time quenching technology is adopted, the first quenching temperature is higher than the AC3 temperature, and the range of a heat affected zone of the first quenching is 55-65 mm; the second quenching temperature is slightly lower than the AC3 temperature, and the range of a heat affected zone of the second quenching is 35-55 mm; the third quenching temperature is between the second quenching temperature and the AC1 temperature, and the range of a heat affected zone of the third quenching is 10-35 mm. Namely, a three-time quenching double-phase region is formed in the weld line region, and after tempering heat treatment, the whole weld region is a double-phase structure of a tempered sorbite structure and a ferrite structure which are distributed in a dispersed manner, wherein the ferrite structure is not less than 25%.

2. The drill rod composite tissue obtained by the method has excellent toughness and plasticity, the diffusion coefficient of hydrogen is increased, and the drill rod composite tissue has good hydrogen sulfide stress corrosion resistance.

Drawings

FIG. 1 shows the first quenching heating range and two-phase zone of the drill rod welding zone.

FIG. 2 shows the second quenching heating range and the two-phase zone of the drill rod weld zone.

FIG. 3 shows the third quenching heating range and the two-phase zone of the drill rod welding zone.

FIG. 4 is a schematic diagram of a drill pipe weld zone full wall thickness hardness test point.

FIG. 5 is a weld line microstructure according to example 1 of the present invention.

FIG. 6 is a weld line microstructure according to example 2 of the present invention.

FIG. 7 is a weld line microstructure according to example 3 of the present invention.

FIG. 8 is a control 1 weld line microstructure.

FIG. 9 is a weld line microstructure according to example 4 of the present invention.

FIG. 10 is a weld line microstructure according to example 5 of the present invention.

FIG. 11 is a microstructure of a weld line of example 6 of the present invention.

Fig. 12 is a control 2 weld line microstructure.

In the figure: the test point comprises a 1-drill rod welding zone outer wall, a 2-drill rod welding zone inner wall, a 3-drill rod welding zone pipe body side, a 4-drill rod welding zone joint side, a 5-weld line, a 6-first quenching influence zone, a 7-second quenching influence zone, an 8-third quenching influence zone and a 9-welding zone full wall thickness hardness test point.

Detailed Description

The technical solution of the present invention will be described in further detail with reference to specific embodiments.

The invention provides a heat treatment method for improving the sulfur resistance of a high-steel-grade sulfur-resistant drill pipe welding area, wherein the drill pipe welding area is formed by inertia friction welding of a 120S steel-grade or 125S steel-grade sulfur-resistant pipe body and a 120S steel-grade sulfur-resistant joint, and the heat treatment of the drill pipe welding area comprises primary quenching, secondary quenching, tertiary quenching and tempering.

And respectively selecting the same batch of 120S steel-grade sulfur-resistant drill pipe bodies and the same batch of 120S steel-grade sulfur-resistant joints for friction welding, and selecting the same batch of 125S steel-grade sulfur-resistant drill pipe bodies and the same batch of 120S steel-grade sulfur-resistant joints (the same batch as the joints) for friction welding. The yield strength of the 120S steel-grade sulfur-resistant pipe body is 867MPa, the yield strength of the 125S steel-grade sulfur-resistant pipe body is 905MPa, the yield strength of the 120S steel-grade sulfur-resistant joint is not less than 889MPa, and the sulfur resistance of the three product materials meets the requirement of no fracture within 720 hours under specified loading stress. And (3) carrying out heat treatment on the welded welding area, and respectively testing the strength and plasticity performance, the hardness performance, the impact toughness performance and the hydrogen sulfide stress corrosion resistance of 1 tensile test, 1 full-section hardness test, 1 group (3) of impact tests and 2 groups (6) of sulfur resistance tests after the heat treatment of each drill rod welding area.

FIG. 1 is a schematic view of the first quenching heating range and the two-phase region of the drill rod weld zone.

FIG. 2 is a schematic view of a second quenching heating range and a two-phase region of a drill pipe weld zone.

FIG. 3 is a schematic view of a third quenching heating range and a two-phase region of a drill rod welding zone.

In the figure: the test point comprises a 1-drill rod welding zone outer wall, a 2-drill rod welding zone inner wall, a 3-drill rod welding zone pipe body side, a 4-drill rod welding zone joint side, a 5-weld line, a 6-first quenching influence zone, a 7-second quenching influence zone, an 8-third quenching influence zone and a 9-welding zone full wall thickness hardness test point. Fig. 1-3 are schematic illustrations for ease of understanding.

The 120S steel grade sulfur-resistant drill pipe body and the 120S steel grade drill pipe joint are selected to carry out 4 groups of experiments in examples 1-3 and a control group 1.

Example 1

After friction welding and welding zone annealing of the 120S steel grade sulfur-resistant drill pipe body and the 120S steel grade drill pipe joint, the welding zone heat treatment is carried out by adopting the technical method of the invention:

the first quenching specifically comprises the following steps: (1) selecting a quenching heating coil with the width of 45mm, and conveying the welding area of the drill rod to the position of the quenching heating coil, wherein the center of the quenching heating coil is aligned with a welding line; (2) raising the temperature of the welding area to 830 ℃ in 50s, and keeping the temperature for 100 s; (3) the quenching cooling adopts the water-soluble PAG medium with the concentration of 12.5 percent sprayed outside and compressed air sprayed inside.

Step two, the second quenching specifically comprises the following steps: (1) selecting a quenching heating coil with the width of 30mm, and conveying the welding area of the drill rod to the position of the quenching heating coil, wherein the center of the quenching heating coil is aligned to the welding line; (2) raising the temperature of the welding area to 800 ℃ in 40s, and keeping the temperature for 90 s; (3) the quenching cooling adopts the water-soluble PAG medium with the concentration of 12.5 percent sprayed outside and compressed air sprayed inside.

Step three, quenching for the third time specifically comprises the following steps: (1) selecting a quenching heating coil with the width of 15mm, and conveying the welding area of the drill rod to the position of the quenching heating coil, wherein the center of the quenching heating coil is aligned with a welding line; (2) raising the temperature of the welding area to 750 ℃ in 30s, and preserving the temperature for 80 s; (3) the quenching cooling adopts the water-soluble PAG medium with the concentration of 12.5 percent sprayed outside and compressed air sprayed inside.

Step four, tempering specifically comprises: (1) a tempering heating coil with the width of 75mm is selected, the welding area of the drill rod is sent to the position of the tempering heating coil, and the center of the tempering heating coil is aligned with a welding line; (2) raising the temperature of the welding area to 670 ℃ in 60s, and preserving the temperature for 220 s; (3) the air was cooled to room temperature.

Example 2

After friction welding and welding zone annealing of the 120S steel grade sulfur-resistant drill pipe body and the 120S steel grade drill pipe joint, the welding zone heat treatment is carried out by adopting the technical method of the invention:

the first quenching specifically comprises the following steps: (1) selecting a quenching heating coil with the width of 45mm, and conveying the welding area of the drill rod to the position of the quenching heating coil, wherein the center of the quenching heating coil is aligned with a welding line; (2) raising the temperature of the welding area to 860 ℃ in 70s, and keeping the temperature for 120 s; (3) the quenching cooling adopts the water-soluble PAG medium with the concentration of 12.5 percent sprayed outside and compressed air sprayed inside.

Step two, the second quenching specifically comprises the following steps: (1) selecting a quenching heating coil with the width of 30mm, and conveying the welding area of the drill rod to the position of the quenching heating coil, wherein the center of the quenching heating coil is aligned to the welding line; (2) raising the temperature of the welding area to 830 ℃ in 60s, and keeping the temperature for 110 s; (3) the quenching cooling adopts the water-soluble PAG medium with the concentration of 12.5 percent sprayed outside and compressed air sprayed inside.

Step three, quenching for the third time specifically comprises the following steps: (1) selecting a quenching heating coil with the width of 15mm, and conveying the welding area of the drill rod to the position of the quenching heating coil, wherein the center of the quenching heating coil is aligned with a welding line; (2) raising the temperature of the welding area to 800 ℃ in 50s, and keeping the temperature for 100 s; (3) the quenching cooling adopts the water-soluble PAG medium with the concentration of 12.5 percent sprayed outside and compressed air sprayed inside.

Step four, tempering specifically comprises: (1) a tempering heating coil with the width of 75mm is selected, the welding area of the drill rod is sent to the position of the tempering heating coil, and the center of the tempering heating coil is aligned with a welding line; (2) raising the temperature of the welding area to 710 ℃ in 80s, and keeping the temperature for 240 s; (3) the air was cooled to room temperature.

Example 3

After friction welding and welding zone annealing of the 120S steel grade sulfur-resistant drill pipe body and the 120S steel grade drill pipe joint, the welding zone heat treatment is carried out by adopting the technical method of the invention:

the first quenching specifically comprises the following steps: (1) selecting a quenching heating coil with the width of 45mm, and conveying the welding area of the drill rod to the position of the quenching heating coil, wherein the center of the quenching heating coil is aligned with a welding line; (2) raising the temperature of the welding area to 845 ℃ in 60s, and preserving the temperature for 110 s; (3) the quenching cooling adopts the water-soluble PAG medium with the concentration of 12.5 percent sprayed outside and compressed air sprayed inside.

Step two, the second quenching specifically comprises the following steps: (1) selecting a quenching heating coil with the width of 30mm, and conveying the welding area of the drill rod to the position of the quenching heating coil, wherein the center of the quenching heating coil is aligned to the welding line; (2) raising the temperature of the welding area to 815 ℃ in 50s, and keeping the temperature for 100 s; (3) the quenching cooling adopts the water-soluble PAG medium with the concentration of 12.5 percent sprayed outside and compressed air sprayed inside.

Step three, quenching for the third time specifically comprises the following steps: (1) selecting a quenching heating coil with the width of 15mm, and conveying the welding area of the drill rod to the position of the quenching heating coil, wherein the center of the quenching heating coil is aligned with a welding line; (2) raising the temperature of the welding area to 780 ℃ in 40s, and preserving the temperature for 90 s; (3) the quenching cooling adopts the water-soluble PAG medium with the concentration of 12.5 percent sprayed outside and compressed air sprayed inside.

Step four, tempering specifically comprises: (1) a tempering heating coil with the width of 75mm is selected, the welding area of the drill rod is sent to the position of the tempering heating coil, and the center of the tempering heating coil is aligned with a welding line; (2) raising the temperature of the welding area to 690 ℃ in 70s, and keeping the temperature for 230 s; (3) the air was cooled to room temperature.

Control group 1

After friction welding and welding zone annealing of the 120S steel grade sulfur-resistant drill pipe body and the 120S steel grade drill pipe joint, performing welding zone heat treatment by adopting a conventional process method:

step one, quenching heat treatment, namely conveying a welding area of a drill rod to a position of a quenching heating coil, wherein the center of the quenching heating coil is aligned with a weld line; raising the temperature of the welding area to 880 ℃ in 70s, and keeping the temperature for 130 s; the quenching cooling adopts the water-soluble PAG medium with the external spraying concentration of 12.5 percent and the compressed air is sprayed in;

step two, tempering heat treatment, namely conveying the welding area of the drill rod to the position of a tempering heating coil, wherein the center of the tempering heating coil is aligned with a welding line; raising the temperature of the welding area to 685 ℃ in 70s, and keeping the temperature for 230 s; cooling the air to room temperature;

the results of 120S high-grade steel sulfur-resistant drill pipe weld examples and comparative examples are shown in tables 1, 2 and 3, the microstructures of weld examples 1-3 using the process of the present invention are shown in fig. 5, 6 and 7, and the microstructure of weld control group 1 using the conventional process is shown in fig. 8. The experimental result shows that for the 120S high-grade steel sulfur-resistant drill rod, compared with the conventional process method, the process method adopted in the heat treatment of the welding area has the advantages that the microstructure of the welding line area is a dual-phase structure of tempered sorbite and ferrite, the plasticity and impact toughness of the welding area are improved, the hardness value of the welding line of the welding area is obviously reduced, the deviation of the hardness value is smaller, and the hydrogen sulfide stress corrosion resistance is obviously improved.

The 125S steel-grade sulfur-resistant drill pipe body and the 120S steel-grade drill pipe joint are selected to carry out 4 experiments in examples 4-6 and a control group 2.

Example 4

After friction welding and welding zone annealing of the 125S steel-grade sulfur-resistant drill pipe body and the 120S steel-grade drill pipe joint, the welding zone heat treatment is carried out by adopting the technical method of the invention:

the first quenching specifically comprises the following steps: (1) selecting a quenching heating coil with the width of 45mm, and conveying the welding area of the drill rod to the position of the quenching heating coil, wherein the center of the quenching heating coil is aligned with a welding line; (2) raising the temperature of the welding area to 830 ℃ in 50s, and keeping the temperature for 100 s; (3) the quenching cooling adopts the water-soluble PAG medium with the concentration of 12.5 percent sprayed outside and compressed air sprayed inside.

Step two, the second quenching specifically comprises the following steps: (1) selecting a quenching heating coil with the width of 30mm, and conveying the welding area of the drill rod to the position of the quenching heating coil, wherein the center of the quenching heating coil is aligned to the welding line; (2) raising the temperature of the welding area to 800 ℃ in 40s, and keeping the temperature for 90 s; (3) the quenching cooling adopts the water-soluble PAG medium with the concentration of 12.5 percent sprayed outside and compressed air sprayed inside.

Step three, quenching for the third time specifically comprises the following steps: (1) selecting a quenching heating coil with the width of 15mm, and conveying the welding area of the drill rod to the position of the quenching heating coil, wherein the center of the quenching heating coil is aligned with a welding line; (2) raising the temperature of the welding area to 750 ℃ in 30s, and preserving the temperature for 80 s; (3) the quenching cooling adopts the water-soluble PAG medium with the concentration of 12.5 percent sprayed outside and compressed air sprayed inside.

Step four, tempering specifically comprises: (1) a tempering heating coil with the width of 75mm is selected, the welding area of the drill rod is sent to the position of the tempering heating coil, and the center of the tempering heating coil is aligned with a welding line; (2) raising the temperature of the welding area to 670 ℃ in 60s, and preserving the temperature for 220 s; (3) the air was cooled to room temperature.

Example 5

After friction welding and welding zone annealing of the 125S steel-grade sulfur-resistant drill pipe body and the 120S steel-grade drill pipe joint, the welding zone heat treatment is carried out by adopting the technical method of the invention:

the first quenching specifically comprises the following steps: (1) selecting a quenching heating coil with the width of 45mm, and conveying the welding area of the drill rod to the position of the quenching heating coil, wherein the center of the quenching heating coil is aligned with a welding line; (2) raising the temperature of the welding area to 860 ℃ in 70s, and keeping the temperature for 120 s; (3) the quenching cooling adopts the water-soluble PAG medium with the concentration of 12.5 percent sprayed outside and compressed air sprayed inside.

Step two, the second quenching specifically comprises the following steps: (1) selecting a quenching heating coil with the width of 30mm, and conveying the welding area of the drill rod to the position of the quenching heating coil, wherein the center of the quenching heating coil is aligned to the welding line; (2) raising the temperature of the welding area to 830 ℃ in 60s, and keeping the temperature for 110 s; (3) the quenching cooling adopts the water-soluble PAG medium with the concentration of 12.5 percent sprayed outside and compressed air sprayed inside.

Step three, quenching for the third time specifically comprises the following steps: (1) selecting a quenching heating coil with the width of 15mm, and conveying the welding area of the drill rod to the position of the quenching heating coil, wherein the center of the quenching heating coil is aligned with a welding line; (2) raising the temperature of the welding area to 800 ℃ in 50s, and keeping the temperature for 100 s; (3) the quenching cooling adopts the water-soluble PAG medium with the concentration of 12.5 percent sprayed outside and compressed air sprayed inside.

Step four, tempering specifically comprises: (1) a tempering heating coil with the width of 75mm is selected, the welding area of the drill rod is sent to the position of the tempering heating coil, and the center of the tempering heating coil is aligned with a welding line; (2) raising the temperature of the welding area to 710 ℃ in 80s, and keeping the temperature for 240 s; (3) cooling the air to room temperature;

example 6

After friction welding and welding zone annealing of the 125S steel-grade sulfur-resistant drill pipe body and the 120S steel-grade drill pipe joint, the welding zone heat treatment is carried out by adopting the technical method of the invention:

the first quenching specifically comprises the following steps: (1) selecting a quenching heating coil with the width of 45mm, and conveying the welding area of the drill rod to the position of the quenching heating coil, wherein the center of the quenching heating coil is aligned with a welding line; (2) raising the temperature of the welding area to 850 ℃ in 60s, and keeping the temperature for 110 s; (3) the quenching cooling adopts the water-soluble PAG medium with the concentration of 12.5 percent sprayed outside and compressed air sprayed inside.

Step two, the second quenching specifically comprises: (1) selecting a quenching heating coil with the width of 30mm, and conveying the welding area of the drill rod to the position of the quenching heating coil, wherein the center of the quenching heating coil is aligned to the welding line; (2) raising the temperature of the welding area to 820 ℃ in 50s, and keeping the temperature for 100 s; (3) the quenching cooling adopts the water-soluble PAG medium with the concentration of 12.5 percent sprayed outside and compressed air sprayed inside.

Step three, quenching for the third time specifically comprises the following steps: (1) selecting a quenching heating coil with the width of 15mm, and conveying the welding area of the drill rod to the position of the quenching heating coil, wherein the center of the quenching heating coil is aligned with a welding line; (2) raising the temperature of the welding area to 790 ℃ in 40s, and keeping the temperature for 90 s; (3) the quenching cooling adopts the water-soluble PAG medium with the concentration of 12.5 percent sprayed outside and compressed air sprayed inside.

Step four, tempering specifically comprises: (1) a tempering heating coil with the width of 75mm is selected, the welding area of the drill rod is sent to the position of the tempering heating coil, and the center of the tempering heating coil is aligned with a welding line; (2) raising the temperature of the welding area to 690 ℃ in 70s, and keeping the temperature for 230 s; (3) cooling the air to room temperature;

comparative example 2

After friction welding and welding zone annealing of the 125S steel-grade sulfur-resistant drill pipe body and the 120S steel-grade drill pipe joint, performing welding zone heat treatment by adopting a conventional process method:

step one, quenching heat treatment, namely conveying a welding area of the drill rod to a position of a quenching heating coil, wherein the center of the quenching heating coil is aligned with a weld line; raising the temperature of the welding area to 850 ℃ in 70s, and keeping the temperature for 130 s; the quenching cooling adopts the water-soluble PAG medium with the external spraying concentration of 12.5 percent and the compressed air is sprayed in;

secondly, tempering heat treatment, namely conveying the welding area of the drill rod to a tempering heating coil, wherein the center of the tempering heating coil is aligned with a welding line; raising the temperature of the welding area to 695 ℃ in 70s, and keeping the temperature for 230 s; the air was cooled to room temperature.

The experimental results of the 125S high-grade steel sulfur-resistant drill pipe weld zone examples and comparative examples are shown in tables 4, 5 and 6. The microstructures of examples 1-3 of the lands using the process of the present invention are shown in fig. 9, 10 and 11, and the microstructure of control 2 of the lands using the conventional process is shown in fig. 12. The experimental result shows that for 125S high-steel-grade sulfur-resistant drill rods, compared with the conventional process method, the process method adopted in the heat treatment of the welding area has the advantages that the microstructure of the welding line area is a dual-phase structure of tempered sorbite and ferrite, the plasticity and impact toughness of the welding area are improved, the hardness value of the welding line of the welding area is obviously reduced, the deviation of the hardness value is smaller, and the hydrogen sulfide stress corrosion resistance is obviously improved.

TABLE 1120S mechanical test results for weld zone of high-grade steel sulfur-resistant drill pipe

Surface 2120S high steel grade sulfur-resistant drill pipe weld zone full section Hardness (HRC)

TABLE 3120S HIGH STEEL-GRADE SULFUR-RESISTANT DRILL ROD WELDING ZONE HYDROGEN SULFUR STRESS CORROSION RESISTANCE

TABLE 4125S mechanical test results for weld zone of high-grade steel sulfur-resistant drill pipe

TABLE 5125S high-grade steel grade Sulfur-resistant drill pipe weld full section Hardness (HRC)

Resistance to hydrogen sulfide stress corrosion of high-grade steel weld zone of sulfur-resistant drill pipe in table 6125S

Although the preferred embodiments of the present patent have been described in detail, the present patent is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present patent within the knowledge of those skilled in the art.