A high-strength low-alloy structural steel drill rod for mining

Abstract

The invention discloses a high-strength low-alloy structural steel drill rod for mines, wherein the drill rod is made of the following raw materials in percentage by mass: 0.22%-0.28% carbon, 0.107%-0.17% vanadium, 0.10%-0.20% silicon, 0.20%-0.40% manganese, 0.06%-0.08% aluminum, 2.55%-2.95% nickel, 0.70%-0.80% molybdenum, 1.45%-1.95% chromium, 0.10%-0.15% copper, 0.008%-0.01% phosphorus, 0.008%-0.01% sulfur, and the balance is iron and inevitable trace elements. The preparation method of the invention is simple, and the obtained low-alloy structural steel drill rod has excellent high temperature resistance, wear resistance and compression resistance, high overall strength, strong impact resistance, not easy to deform and damage, and long service life.

Description

Technical Field

[0001] The invention relates to the technical field of drill rod manufacturing, in particular to a high-strength low-alloy structural steel drill rod for mining. Background Art

[0002] Drill pipe is a hexagonal or square steel pipe with a threaded tail, used to connect the surface equipment of the drilling rig and the drilling and grinding equipment or bottom hole device at the bottom of the well. The purpose of the drill pipe is to transport drilling mud to the drill bit and raise, lower or rotate the bottom hole device together with the drill bit. The drill pipe must be able to withstand huge internal and external pressure, twisting, bending and vibration.

[0003] The current processing process of drill rods for mining cannot make the drill rod structure uniform, nor can it improve the strength and toughness of the drill rod, which in turn affects the service life of the drill rod. Therefore, it is necessary to produce a high-strength low-alloy structural steel drill rod for mining. Summary of the invention

[0004] The object of the present invention is to provide a high-strength low-alloy structural steel drill rod for mining, so as to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for manufacturing a high-strength low-alloy structural steel drill rod for mining, the manufacturing method comprising the following steps:

[0006] A. Prepare all raw materials and mix them, then add them into a non-vacuum induction melting furnace for vacuum induction melting, and then cast them into steel ingots;

[0007] B. Put the steel ingot into the carburizing furnace, heat the carburizing furnace, and continuously introduce propane gas during the heating process;

[0008] C. Then slowly raise the temperature of the carburizing furnace to 990°C and introduce a mixture of ammonia and ethanol to complete the diffusion of the steel ingot;

[0009] D. Send the diffused steel ingot into the quenching chamber for quenching, and slowly cool the steel ingot into the quenching oil to 80℃-120℃;

[0010] E. Finally, the steel ingot is forged and rolled to form a low alloy structural steel drill pipe;

[0011] In step A, the smelting temperature is 1800°C-2000°C, and the refining time is 50min-70min;

[0012] In the step B, the propane gas is introduced at an amount of 0.1 L-0.16 L / h, the carburizing furnace is heated to 940° C.-960° C., and then kept at a constant temperature for 60 min-90 min to perform deep carburizing, with a carbon potential of 0.9-1.2;

[0013] In step C, the amount of ammonia and ethanol mixture introduced is 30-50 L / h, and the diffusion time is 90 min-120 min;

[0014] The cooling time in step D is 40min-60min;

[0015] In step D, quenching is performed by using graded quenching oil quenching cooling method;

[0016] The drill pipe is made of the following raw materials with the following mass percentages: carbon 0.22%-0.28%, vanadium 0.107%-0.17%, silicon 0.10%-0.20%, manganese 0.20%-0.40%, aluminum 0.06%-0.08%, nickel 2.55%-2.95%, molybdenum 0.70%-0.80%, chromium 1.45%-1.95%, copper 0.10%-0.15%, phosphorus 0.008%-0.01%, sulfur 0.008%-0.01%, and the balance is iron and inevitable trace elements.

[0017] Compared with the prior art, the beneficial effects of the present invention are: the preparation method of the present invention is simple, and the prepared low-alloy structural steel drill rod has excellent high temperature resistance, wear resistance and pressure resistance, high overall strength, strong impact resistance, is not easy to deform and damage, and has a long service life.

[0018] The carbon added in the present invention can improve the strength of the drill pipe. When the carbon content is too low, the effect is not obvious; when the carbon content is too high, the toughness of the drill pipe will be greatly reduced and quenching cracks may occur. The preferred carbon content of the present invention is 0.22%-0.28%, which can effectively improve the structural strength of the drill pipe.

[0019] The vanadium added in the present invention can maintain high strength at high temperatures, and has low thermal conductivity and electrical conductivity as well as strong ferromagnetism, which can ensure the strength of the drill pipe;

[0020] The silicon added in the present invention is an element that must be added to improve the casting performance, but too high a content will increase the brittleness of the drill pipe. The present invention preferably has a silicon content of 0.10%-0.20%;

[0021] The manganese added in the present invention can delay the transformation of austenite to ferrite and bainite during high-temperature cooling, thereby obtaining more quenched martensite and improving the hardenability of the drill pipe;

[0022] The aluminum added in the present invention has excellent oxidation resistance and ductility, and can also improve the strength and toughness of the drill pipe;

[0023] The molybdenum added in the present invention can increase the tempering stability during the processing of the drill pipe, which is beneficial to increase the tempering temperature, thereby reducing the residual stress after heat treatment and improving the impact toughness;

[0024] The copper, phosphorus and sulfur added in the present invention can improve the strength and hardenability of the drill pipe; the added nickel can generate stable carbides and carbonitrides with carbon and nitrogen in the drill pipe, and can also disperse the carbides to form steel with fine crystals, thereby improving the structural strength of the drill pipe.

[0025] The manufacturing method of the invention can improve the wear resistance of the drill rod.

[0026] The above description is only an overview of the technical solution of the embodiment of the present application. In order to more clearly understand the technical means of the embodiment of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the embodiment of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present application, a brief introduction will be given below to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 This is a micrograph of the core structure after quenching and tempering;

[0029] Figure 2 Micrograph of grain size. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used in the specification of the application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0032] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase "embodiments" in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0033] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings.

[0034] The present invention provides the following technical solution: a high-strength low-alloy structural steel drill rod for mining, the drill rod being made of the following raw materials in respective mass percentages: carbon 0.22%-0.28%, vanadium 0.107%-0.17%, silicon 0.10%-0.20%, manganese 0.20%-0.40%, aluminum 0.06%-0.08%, nickel 2.55%-2.95%, molybdenum 0.70%-0.80%, chromium 1.45%-1.95%, copper 0.10%-0.15%, phosphorus 0.008%-0.01%, sulfur 0.008%-0.01%, and the remainder being iron and inevitable trace elements.

[0035] Embodiment 1:

[0036] The drill pipe is made of the following raw materials in percentage by mass: carbon 0.22%, vanadium 0.107%, silicon 0.10%, manganese 0.20%, aluminum 0.06%, nickel 2.55%, molybdenum 0.70%, chromium 1.45%, copper 0.10%, phosphorus 0.008%, sulfur 0.008%, and the remainder is iron and inevitable trace elements.

[0037] The manufacturing method of this embodiment comprises the following steps:

[0038] A. Prepare all raw materials and mix them, then add them into a non-vacuum induction melting furnace for vacuum induction melting, and then cast them into steel ingots;

[0039] B. Put the steel ingot into the carburizing furnace, heat the carburizing furnace, and continuously introduce propane gas during the heating process;

[0040] C. Then slowly raise the temperature of the carburizing furnace to 990°C and introduce a mixture of ammonia and ethanol to complete the diffusion of the steel ingot;

[0041] D. Send the diffused steel ingot into the quenching chamber for quenching, and slowly cool the steel ingot into the quenching oil to 80°C;

[0042] E. Finally, the steel ingot is forged and rolled to form a low alloy structural steel drill rod.

[0043] In this embodiment, the smelting temperature in step A is 1800° C. and the refining time is 50 min.

[0044] In this embodiment, in step B, the propane gas introduction rate is 0.1 L / h, the carburizing furnace is heated to 940° C., and then kept at a constant temperature for 60 minutes for deep carburizing, and the carbon potential is 0.9.

[0045] In this embodiment, the amount of ammonia and ethanol mixture introduced in step C is 30 L / h, and the diffusion time is 90 min.

[0046] In this embodiment, the cooling time in step D is 40 minutes.

[0047] In this embodiment, the quenching in step D adopts a graded quenching oil quenching cooling method.

[0048] Embodiment 2:

[0049] The drill pipe is made of the following raw materials in percentage by mass: carbon 0.28%, vanadium 0.17%, silicon 0.20%, manganese 0.40%, aluminum 0.08%, nickel 2.95%, molybdenum 0.80%, chromium 1.95%, copper 0.15%, phosphorus 0.01%, sulfur 0.01%, and the balance is iron and inevitable trace elements.

[0050] The manufacturing method of this embodiment comprises the following steps:

[0051] A. Prepare all raw materials and mix them, then add them into a non-vacuum induction melting furnace for vacuum induction melting, and then cast them into steel ingots;

[0052] B. Put the steel ingot into the carburizing furnace, heat the carburizing furnace, and continuously introduce propane gas during the heating process;

[0053] C. Then slowly raise the temperature of the carburizing furnace to 990°C and introduce a mixture of ammonia and ethanol to complete the diffusion of the steel ingot;

[0054] D. Send the diffused steel ingot into the quenching chamber for quenching, and slowly cool the steel ingot into the quenching oil to 120°C;

[0055] E. Finally, the steel ingot is forged and rolled to form a low alloy structural steel drill rod.

[0056] In this embodiment, the smelting temperature in step A is 2000° C. and the refining time is 70 min.

[0057] In this embodiment, in step B, the propane gas introduction rate is 0.16 L / h, the carburizing furnace is heated to 960° C., and then kept at a constant temperature for 90 minutes for deep carburizing, and the carbon potential is 1.2.

[0058] In this embodiment, the amount of ammonia and ethanol mixture introduced in step C is 50 L / h, and the diffusion time is 120 min.

[0059] In this embodiment, the cooling time in step D is 60 minutes.

[0060] In this embodiment, the quenching in step D adopts a graded quenching oil quenching cooling method.

[0061] Embodiment three:

[0062] The drill pipe is made of the following raw materials in percentage by mass: carbon 0.23%, vanadium 0.11%, silicon 0.12%, manganese 0.25%, aluminum 0.06%, nickel 2.65%, molybdenum 0.72%, chromium 1.49%, copper 0.11%, phosphorus 0.009%, sulfur 0.009%, and the remainder is iron and inevitable trace elements.

[0063] The manufacturing method of this embodiment comprises the following steps:

[0064] A. Prepare all raw materials and mix them, then add them into a non-vacuum induction melting furnace for vacuum induction melting, and then cast them into steel ingots;

[0065] B. Put the steel ingot into the carburizing furnace, heat the carburizing furnace, and continuously introduce propane gas during the heating process;

[0066] C. Then slowly raise the temperature of the carburizing furnace to 990°C and introduce a mixture of ammonia and ethanol to complete the diffusion of the steel ingot;

[0067] D. Send the diffused steel ingot into the quenching chamber for quenching, and slowly cool the steel ingot into the quenching oil to 90°C;

[0068] E. Finally, the steel ingot is forged and rolled to form a low alloy structural steel drill rod.

[0069] In this embodiment, the smelting temperature in step A is 1850° C. and the refining time is 55 min.

[0070] In this embodiment, in step B, the propane gas introduction rate is 0.11 L / h, the carburizing furnace is heated to 945° C., and then kept at a constant temperature for 65 minutes to perform deep carburizing, and the carbon potential is 1.

[0071] In this embodiment, the flow rate of the mixture of ammonia and ethanol in step C is 35 L / h, and the diffusion time is 95 min.

[0072] In this embodiment, the cooling time in step D is 45 minutes.

[0073] In this embodiment, the quenching in step D adopts a graded quenching oil quenching cooling method.

[0074] Embodiment 4:

[0075] The drill pipe is made of the following raw materials in percentage by mass: carbon 0.27%, vanadium 0.16%, silicon 0.19%, manganese 0.36%, aluminum 0.07%, nickel 2.85%, molybdenum 0.79%, chromium 1.85%, copper 0.14%, phosphorus 0.009%, sulfur 0.009%, and the remainder is iron and inevitable trace elements.

[0076] The manufacturing method of this embodiment comprises the following steps:

[0077] A. Prepare all raw materials and mix them, then add them into a non-vacuum induction melting furnace for vacuum induction melting, and then cast them into steel ingots;

[0078] B. Put the steel ingot into the carburizing furnace, heat the carburizing furnace, and continuously introduce propane gas during the heating process;

[0079] C. Then slowly raise the temperature of the carburizing furnace to 990°C and introduce a mixture of ammonia and ethanol to complete the diffusion of the steel ingot;

[0080] D. Send the diffused steel ingot into the quenching chamber for quenching, and slowly cool the steel ingot into the quenching oil to 110°C;

[0081] E. Finally, the steel ingot is forged and rolled to form a low alloy structural steel drill rod.

[0082] In this embodiment, the smelting temperature in step A is 1950° C. and the refining time is 65 min.

[0083] In this embodiment, in step B, the propane gas introduction rate is 0.15 L / h, the carburizing furnace is heated to 955° C., and then kept at a constant temperature for 85 minutes for deep carburizing, and the carbon potential is 1.1.

[0084] In this embodiment, the flow rate of the mixture of ammonia and ethanol in step C is 45 L / h, and the diffusion time is 110 min.

[0085] In this embodiment, the cooling time in step D is 55 minutes.

[0086] In this embodiment, the quenching in step D adopts a graded quenching oil quenching cooling method.

[0087] Embodiment five:

[0088] The drill pipe is made of the following raw materials in percentage by mass: carbon 0.22%, vanadium 0.17%, silicon 0.10%, manganese 0.40%, aluminum 0.06%, nickel 2.95%, molybdenum 0.70%, chromium 1.95%, copper 0.10%, phosphorus 0.01%, sulfur 0.008%, and the remainder is iron and inevitable trace elements.

[0089] The manufacturing method of this embodiment comprises the following steps:

[0090] A. Prepare all raw materials and mix them, then add them into a non-vacuum induction melting furnace for vacuum induction melting, and then cast them into steel ingots;

[0091] B. Put the steel ingot into the carburizing furnace, heat the carburizing furnace, and continuously introduce propane gas during the heating process;

[0092] C. Then slowly raise the temperature of the carburizing furnace to 990°C and introduce a mixture of ammonia and ethanol to complete the diffusion of the steel ingot;

[0093] D. Send the diffused steel ingot into the quenching chamber for quenching, and slowly cool the steel ingot into the quenching oil to 80°C;

[0094] E. Finally, the steel ingot is forged and rolled to form a low alloy structural steel drill rod.

[0095] In this embodiment, the smelting temperature in step A is 2000° C. and the refining time is 50 min.

[0096] In this embodiment, in step B, the propane gas introduction rate is 0.16 L / h, the carburizing furnace is heated to 940° C., and then kept at a constant temperature for 90 minutes for deep carburizing, and the carbon potential is 0.9.

[0097] In this embodiment, the amount of ammonia and ethanol mixture introduced in step C is 50 L / h, and the diffusion time is 90 min.

[0098] In this embodiment, the cooling time in step D is 60 minutes.

[0099] In this embodiment, the quenching in step D adopts a graded quenching oil quenching cooling method.

[0100] Embodiment six:

[0101] The drill pipe is made of the following raw materials in percentage by mass: carbon 0.25%, vanadium 0.14%, silicon 0.15%, manganese 0.30%, aluminum 0.07%, nickel 2.75%, molybdenum 0.75%, chromium 1.85%, copper 0.13%, phosphorus 0.009%, sulfur 0.009%, and the remainder is iron and inevitable trace elements.

[0102] The manufacturing method of this embodiment comprises the following steps:

[0103] A. Prepare all raw materials and mix them, then add them into a non-vacuum induction melting furnace for vacuum induction melting, and then cast them into steel ingots;

[0104] B. Put the steel ingot into the carburizing furnace, heat the carburizing furnace, and continuously introduce propane gas during the heating process;

[0105] C. Then slowly raise the temperature of the carburizing furnace to 990°C and introduce a mixture of ammonia and ethanol to complete the diffusion of the steel ingot;

[0106] D. Send the diffused steel ingot into the quenching chamber for quenching, and slowly cool the steel ingot to 100°C in the quenching oil;

[0107] E. Finally, the steel ingot is forged and rolled to form a low alloy structural steel drill rod.

[0108] In this embodiment, the smelting temperature in step A is 1900° C. and the refining time is 60 min.

[0109] In this embodiment, in step B, the propane gas introduction rate is 0.13 L / h, the carburizing furnace is heated to 950° C., and then kept at a constant temperature for 75 minutes to perform deep carburizing, and the carbon potential is 1.

[0110] In this embodiment, the amount of ammonia and ethanol mixture introduced in step C is 40 L / h, and the diffusion time is 105 min.

[0111] In this embodiment, the cooling time in step D is 50 minutes.

[0112] In this embodiment, the quenching in step D adopts a graded quenching oil quenching cooling method.

[0113] Experimental example:

[0114] The mechanical properties of the drill pipe prepared by the embodiment of the present invention were tested, and the results obtained were as follows:

[0115] End hardenability:

[0116] The hardness test within the range of 45mm from the surface is as follows:

[0117] Distance from surface (mm) 1.5 3 6 9 12 15 20 25 30 35 40 45 Hardness (HRc) 47 46.75 45.75 46.25 46 45 45.25 45 44.75 44.5 44.75 45.25

[0118] Fatigue test:

[0119] The conditional fatigue limit and finite life fatigue life are as follows:

[0120] Conditional fatigue limit: 625.9MPa

[0121] Example <![CDATA[σ i / mpa]]> <![CDATA[N i =N 50 / 10 3 ]]> <![CDATA[lgN i ]]> Embodiment 1 880 175 5.2430 Embodiment 2 840 234 5.3692 Embodiment 3 800 277 5.4424 Embodiment 4 760 622 5.7938 Embodiment 5 720 713 5.8531 Embodiment 6 740 708 5.6254

[0122] Microstructure:

[0123] like Figure 1 and Figure 2 As shown, the core of the finished sample is a uniform tempered martensite structure, indicating that the core has been completely hardened during the quenching and tempering heat treatment process, and the grain size is finer than or equal to level 8.

[0124] The carbon added in the present invention can improve the strength of the drill pipe. When the carbon content is too low, the effect is not obvious; when the carbon content is too high, the toughness of the drill pipe will be greatly reduced and quenching cracks may occur. The preferred carbon content of the present invention is 0.22%-0.28%, which can effectively improve the structural strength of the drill pipe.

[0125] The vanadium added in the present invention can maintain high strength at high temperatures, and has low thermal conductivity and electrical conductivity as well as strong ferromagnetism, which can ensure the strength of the drill pipe;

[0126] The silicon added in the present invention is an element that must be added to improve the casting performance, but too high a content will increase the brittleness of the drill pipe. The present invention preferably has a silicon content of 0.10%-0.20%;

[0127] The manganese added in the present invention can delay the transformation of austenite to ferrite and bainite during high-temperature cooling, thereby obtaining more quenched martensite and improving the hardenability of the drill pipe;

[0128] The aluminum added in the present invention has excellent oxidation resistance and ductility, and can also improve the strength and toughness of the drill pipe;

[0129] The molybdenum added in the present invention can increase the tempering stability during the processing of the drill pipe, which is beneficial to increase the tempering temperature, thereby reducing the residual stress after heat treatment and improving the impact toughness;

[0130] The copper, phosphorus and sulfur added in the present invention can improve the strength and hardenability of the drill pipe; the added nickel can generate stable carbides and carbonitrides with carbon and nitrogen in the drill pipe, and can also disperse the carbides to form steel with fine crystals, thereby improving the structural strength of the drill pipe.

[0131] The manufacturing method of the invention can improve the wear resistance of the drill rod.

[0132] In summary, the preparation method of the present invention is simple, and the prepared low-alloy structural steel drill rod has excellent high temperature resistance, wear resistance and pressure resistance, high overall strength, strong impact resistance, is not easy to deform and damage, and has a long service life.

[0133] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for manufacturing a high-strength low-alloy structural steel drill rod for mining, characterized in that: The preparation method thereof comprises the following steps: A. Prepare all raw materials and mix them, then add them into a non-vacuum induction melting furnace for vacuum induction melting, and then cast them into steel ingots; B. Put the steel ingot into the carburizing furnace, heat the carburizing furnace, and continuously introduce propane gas during the heating process; C. Then slowly raise the temperature of the carburizing furnace to 990°C and introduce a mixture of ammonia and ethanol to complete the diffusion of the steel ingot; D. Send the diffused steel ingot into the quenching chamber for quenching, and slowly cool the steel ingot into the quenching oil to 80℃-120℃; E. Finally, the steel ingot is forged and rolled to form a low alloy structural steel drill pipe; In step A, the smelting temperature is 1800°C-2000°C, and the refining time is 50min-70min; In the step B, the propane gas is introduced at an amount of 0.1 L-0.16 L / h, the carburizing furnace is heated to 940° C.-960° C., and then kept at a constant temperature for 60 min-90 min to perform deep carburizing, with a carbon potential of 0.9-1.2; In step C, the amount of ammonia and ethanol mixture introduced is 30-50 L / h, and the diffusion time is 90 min-120 min; The cooling time in step D is 40min-60min; In step D, quenching is performed by using graded quenching oil quenching cooling method; The drill pipe is made of the following raw materials with the following mass percentages: carbon 0.22%-0.28%, vanadium 0.107%-0.17%, silicon 0.10%-0.20%, manganese 0.20%-0.40%, aluminum 0.06%-0.08%, nickel 2.55%-2.95%, molybdenum 0.70%-0.80%, chromium 1.45%-1.95%, copper 0.10%-0.15%, phosphorus 0.008%-0.01%, sulfur 0.008%-0.01%, and the balance is iron and inevitable trace elements.

Images