CN108385033B - Steel for KD-grade surface aluminized modified sucker rod and rod body manufacturing method thereof - Google Patents
Steel for KD-grade surface aluminized modified sucker rod and rod body manufacturing method thereof Download PDFInfo
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- CN108385033B CN108385033B CN201810468139.7A CN201810468139A CN108385033B CN 108385033 B CN108385033 B CN 108385033B CN 201810468139 A CN201810468139 A CN 201810468139A CN 108385033 B CN108385033 B CN 108385033B
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
- C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
Abstract
A KD-grade surface aluminized modified steel for a sucker rod and a manufacturing method of a rod body thereof comprise the following components in percentage by weight: c: 0.05-0.08%, Mn: 2.36-2.49%, Cr: 0.5 to 1.0%, Mo: 0.25 to 0.30%, Si: 0.30-0.60%, Nb 0.02-0.04%, S: less than or equal to 0.03%, P: less than or equal to 0.03 percent, Ti: less than or equal to 0.020%, and the balance of iron; the aluminum alloy is prepared by casting, rolling, sizing, air cooling, slow cooling, aluminizing, air cooling and slow cooling. The rod body manufactured by the invention completely meets the requirements of SY5029 standard on performance of KD-grade sucker rod steel, reduces production and manufacturing cost and increases production manufacturability. The high-strength sucker rod steel has high strength, good toughness and plasticity, corrosion resistance and fatigue resistance, good crack-stopping capacity and long service life.
Description
Technical Field
The invention relates to the technical field of petroleum pipe manufacturing, in particular to steel for a KD-grade surface aluminized modified sucker rod and a rod body manufacturing method thereof.
Background
With the development of the petroleum industry, the performance requirement of the surface anticorrosion technology of the sucker rod is continuously improved, and the research of the surface aluminizing modification technology of the sucker rod as an important anticorrosion means is widely regarded.
At present, the KD-grade pumping rod steel used for surface aluminizing modification mostly adopts quenching and tempering treatment, and has the disadvantages of complex process, higher cost and long supply period. In addition, after the surface aluminizing modification treatment, the rod body needs to be subjected to high-temperature quenching and tempering again, so that the aluminized layer on the surface of the rod body has the defects of cavities, cracks, peeling and the like, and the corrosion resistance and the fatigue resistance are reduced. The production process can be simplified and the production cost supply period can be greatly reduced by adopting non-quenched and tempered steel to produce the oil well pipe. Furthermore, after the surface aluminizing modification treatment, the non-quenched and tempered steel does not need to be subjected to high-temperature quenching and tempering treatment, so that the structural integrity of the aluminized layer is greatly protected, and the corrosion resistance, the fatigue resistance and the like of the sucker rod body are improved.
Disclosure of Invention
The invention aims to provide KD-grade surface aluminized modified steel for a sucker rod and a manufacturing method of a rod body of the steel, which have the advantages of simple production process, lower cost, low toughness, good corrosion resistance and long service life.
In order to achieve the purpose, the invention is realized by adopting the following technical scheme:
the KD-grade surface aluminized modified steel for the sucker rod comprises the following components in percentage by weight: c: 0.05-0.08%, Mn: 2.36-2.49%, Cr: 0.5 to 1.0%, Mo: 0.25 to 0.30%, Si: 0.30-0.60%, Nb: 0.02-0.04%, S: less than or equal to 0.03%, P: less than or equal to 0.03 percent, Ti: less than or equal to 0.020%, and the balance of iron and inevitable impurities.
The invention is further improved in that the composition comprises the following components in percentage by weight: c: 0.05 to 0.07%, Mn: 2.36-2.4%, Cr: 0.8-1.0%, Mo: 0.25 to 0.30%, Si: 0.30-0.60%, Nb: 0.03-0.04%, S: less than or equal to 0.03%, P: less than or equal to 0.03 percent, Ti: less than or equal to 0.020%, and the balance of iron and inevitable impurities.
The invention is further improved in that the composition comprises the following components in percentage by weight: c: 0.07 to 0.08%, Mn: 2.4-2.49%, Cr: 0.5-0.8%, Mo: 0.25 to 0.30%, Si: 0.30-0.60%, Nb: 0.02-0.03%, S: less than or equal to 0.03%, P: less than or equal to 0.03 percent, Ti: less than or equal to 0.020%, and the balance of iron and inevitable impurities.
A manufacturing method of a KD-level surface aluminized modified sucker rod comprises the following steps:
1) c, according to weight percentage: 0.05-0.08%, Mn: 2.36-2.49%, Cr: 0.5 to 1.0%, Mo: 0.25 to 0.30%, Si: 0.30-0.60%, Nb: 0.02-0.04%, S: less than or equal to 0.03%, P: less than or equal to 0.03 percent, Ti: less than or equal to 0.020 percent, and the balance of iron and inevitable impurities, and performing smelting, external refining and casting to prepare a bar blank;
2) heating the bar blank to 1180-1200 ℃;
3) rolling by a continuous rolling mill set, wherein the starting temperature of the rolling by the continuous rolling mill set is 1130-1150 ℃, and the finishing temperature is 780-800 ℃;
4) slowly cooling after air cooling;
5) carrying out rapid aluminizing surface treatment on the rod body, wherein the aluminizing temperature is 720-740 ℃, and the time is 5-10 min;
6) and slowly cooling after air cooling.
A further improvement of the invention is that the smelting in step 1) is carried out in a converter or an electric furnace.
A further development of the invention is that the heating in step 2) is carried out in a heating furnace.
The further improvement of the invention is that the slow cooling starting temperature in the step 4) is 400-450 ℃, and the slow cooling heat preservation time is 24 hours.
The invention is further improved in that the aluminizing in the step 5) is carried out in a high-frequency induction aluminizing device.
The further improvement of the invention is that the slow cooling starting temperature in the step 6) is 400-450 ℃, and the slow cooling heat preservation time is 24 hours.
Compared with the prior art, the invention has the following beneficial effects:
the steel for the KD-level surface aluminizing modified sucker rod provided by the invention is mainly composed of low C and a proper amount of Mn, and fine granular bainite is obtained by adding micro alloy elements such as Cr, a small amount of Mo and a trace amount of Ti and combining a slow cooling process, so that the sucker rod steel is ensured to have excellent mechanical properties. The main components have the following functions:
carbon: in the case of sufficient austenitization, the C-curve gradually shifts to the right as the austenitic carbon content increases, and the stability of the supercooled austenite increases. In general, as the carbon content increases, the strength of the steel increases, but the weldability and ductility decrease. The KD-grade surface aluminized modified steel for the sucker rod is designed by adopting 0.05-0.08% of carbon by weight.
Mn is the most main and economic strengthening element for compensating strength loss caused by reduced C content in the steel for the sucker rod, Mn is an element for expanding a gamma phase region, can reduce the gamma → α phase transition temperature of the steel, is beneficial to obtaining a fine phase transition product, can improve the toughness of the steel and reduce the ductile-brittle transition temperature, and the weight percentage content of Mn in the steel for the KD-level surface aluminized modified sucker rod is designed to be within the range of 2.36-2.49%.
Titanium: is a strong N-compound forming element, when the austenitizing temperature is soaked, the fine TiN precipitated phase can effectively inhibit the austenite grains from growing and refine the prior austenite grains, and in addition, the TiN precipitated phase has obvious effect on improving the impact toughness of a welding heat affected zone. The above-mentioned action can be implemented by using trace Ti, so that the weight percentage of Ti selected by said invention is less than or equal to 0.020%.
Chromium: cr is a medium-strength carbide forming element, and generally speaking, Cr can obviously improve the stability and hardenability of metastable austenite, increase the supercooling capacity of austenite, delay ferrite and pearlite transformation and delay bainite transformation, and is favorable for the appearance of a metastable austenite region between a ferrite transformation region and a bainite transformation region. The invention selects the Cr content of 0.5-1.0% by weight.
Niobium: nb is a strong carbide forming element and has a remarkable precipitation strengthening effect, and in addition, Nb has the composite effects of inhibiting austenite phase transformation, delaying high-temperature transformation, solid solution strengthening and the like, and the Nb content is selected to be 0.02-0.04% by weight.
Molybdenum: mo is a medium-strength carbide forming element, improves the hardenability of steel, has stronger action than chromium and is slightly inferior to manganese; molybdenum improves the temper stability of the steel. In combination with chromium, manganese, etc., molybdenum reduces or suppresses temper embrittlement caused by other elements. Molybdenum has a solid solution strengthening effect on ferrite, and simultaneously improves the stability of carbide, thereby improving the strength of steel; the surface of the steel can be passivated in reducing acid and strong oxidizing salt solution, so that the molybdenum can generally improve the corrosion resistance of the steel and prevent the pitting corrosion of the steel in chloride solution. The cost of the Mo alloy is high, and the Mo alloy needs to be properly controlled, and the Mo content is selected to be 0.25-0.30% by weight.
The carbon content is obviously reduced in the invention, and the purpose is to improve the corrosion resistance and the fatigue performance. The purpose of the slight increase of the Mn content is to increase the hardenability ensuring strength requirement, and the purpose of adding Nb is also to increase the hardenability ensuring strength requirement. In addition, the structure of the present invention is mainly granular bainite. The KD-level surface aluminized modified steel for the sucker rod provided by the invention adopts a lath martensite and ultrafine granular bainite structure, completely meets the requirements of API SPEC 11B on the performance of the KD-level steel for the sucker rod, and can reduce the production and manufacturing cost and increase the production manufacturability. Low carbon content in chemical components, microalloying, high impact toughness, good corrosion resistance and long service life.
The manufacturing method of the steel rod body for the KD-level surface aluminized modified sucker rod provided by the invention has the following effects by slowly cooling the rod body after final cooling:
1. eliminating residual stress;
2. the M-A islands are self-tempered, thereby improving the yield strength and impact toughness of the steel.
3. The slow cooling process replaces the tempering heat treatment process, so that energy and cost are saved.
The manufacturing method of the invention does not need a quenching and tempering heat treatment process, and improves the corrosion resistance of the steel for the surface aluminized modified sucker rod. The hot rolling process adopts a slow cooling process, and the structure and the quality of a final product are controlled through reasonable components and processes. More importantly, after the surface aluminizing modification treatment, the rod body is subjected to the slow cooling process after air cooling, and quenching and tempering are not needed, so that the mechanical property requirement is met, more importantly, the organization structure of the aluminized layer is protected, the corrosion resistance of the sucker rod material is obviously improved, and the problems that the structure of the aluminized layer on the surface of the rod body is damaged and the surface corrosion resistance is reduced due to the fact that quenching and tempering are needed again after the surface aluminizing modification treatment in the prior art are solved.
The alloy formula of the invention has the advantages of low C content (0.05-0.08%), certain Cr content (0.5-1.0%), certain Mo content (0.25-0.30%), certain Si content (0.3-0.6%), trace Nb (0.02-0.04%), trace Ti (less than or equal to 0.020), no addition of elements such as Ni and Cu, simple component design and low cost; the appropriate Mn (2.36-2.49%) content makes full use of the phase change strengthening and solid solution strengthening effects of Mn elements; the components are matched with a slow cooling process after hot rolling, so that the comprehensive performance of the product is improved, a flexible hot rolling production process can be adopted, and the productivity is improved. In addition, the product with lower C content has higher strength, and simultaneously keeps good toughness, plasticity, corrosion resistance and fatigue resistance, so that the sucker rod steel has good crack arrest capability.
The performance of the steel rod body for the KD-level surface aluminized modified sucker rod produced by the manufacturing method of the invention can meet the following requirements, and the mechanical property regulation of the SY5029 sucker rod standard on the KD-level sucker rod can be completely met:
(1) tensile properties, target: rm＝795～965MPa，ReL≧590MPa，A≧10％；
(2) And a metallographic structure mainly comprising a fine grained bainite structure.
Drawings
FIG. 1 is a metallographic structure of a steel bar body after aluminizing and slow cooling according to example 1 of the present invention.
FIG. 2 is a metallographic structure of a steel bar body after aluminizing and slow cooling according to embodiment 2 of the present invention.
FIG. 3 is a metallographic structure diagram of a steel bar body after aluminizing and slow cooling according to embodiment 3 of the present invention.
Detailed Description
The present invention will be described in detail below with reference to embodiments in conjunction with the accompanying drawings.
Example 1
A KD-grade surface aluminized modified steel for a sucker rod comprises the following chemical components in percentage by weight: 0.08% of C, 2.49% of Mn, 0.3% of Mo, 0.04% of Nb, 0.6% of Si, 0.0053% of P, 0.0038% of S, 1.0% of Cr, 0.020% of Ti, and the balance of Fe.
The manufacturing method of the steel rod body for the KD-level surface aluminized modified sucker rod comprises the following steps of carrying out converter smelting, external refining and casting on the components according to the weight percentage to obtain a rod blank, and heating the rod blank to 1200 ℃ through a heating furnace; then rolling by a continuous rolling unit, wherein the starting temperature of the rolling by the continuous rolling unit is controlled to be 1150 ℃, and the finishing temperature is controlled to be 780 ℃; air cooling to 400 ℃, stacking, preserving heat and slowly cooling for 24 hours; carrying out rapid aluminizing surface treatment on the rod body by high-frequency induction aluminizing equipment, wherein the aluminizing temperature is 740 ℃, and the aluminizing time is 10 min; air cooling to 450 ℃, stacking, preserving heat and slowly cooling for 24 h.
The mechanical properties of the steel rod body manufactured by the method are that the yield strength is 635MPa, the tensile strength is 865MPa and the elongation is 18.0 percent. The performance index of the high-strength high-toughness steel completely meets the requirements of SY5029 standard on performance of KD-level steel for sucker rods. The metallographic structure of this example is fine grained bainite, see fig. 1.
Example 2
A KD-grade surface aluminized modified steel for a sucker rod comprises the following chemical components in percentage by weight: 0.07% of C, 2.4% of Mn, 0.30% of Mo, 0.02% of Nb, 0.3% of Si, 0.005% of P, 0.006% of S, 0.8% of Cr, 0.020% of Ti, and the balance of Fe.
The manufacturing method of the steel rod body for the KD-level surface aluminized modified sucker rod comprises the following steps of carrying out electric furnace smelting, external refining and casting on the components according to the weight percentage to obtain a rod blank, and heating the rod blank to 1180 ℃ through a heating furnace; then rolling by a continuous rolling unit, wherein the starting temperature of the continuous rolling unit is controlled to be 1130 ℃, and the finishing temperature is controlled to be 800 ℃; air cooling to 400 ℃, stacking, preserving heat and slowly cooling for 24 hours; carrying out rapid aluminizing surface treatment on the rod body by high-frequency induction aluminizing equipment, wherein the aluminizing temperature is 720 ℃, and the aluminizing time is 10 min; air cooling to 400 ℃, stacking, preserving heat and slowly cooling for 24 h.
The mechanical properties of the steel rod body manufactured by the method are 619MPa of yield strength, 835MPa of tensile strength and 17.0 percent of elongation. The performance index of the special high-strength high-toughness high-strength steel completely meets the requirement of API SPEC 11B on the performance of KD-level steel for sucker rods. The metallographic structure of this example is fine grained bainite, see fig. 2.
Example 3
A KD-grade surface aluminized modified steel for a sucker rod comprises the following chemical components in percentage by weight: 0.05% of C, 2.36% of Mn, 0.25% of Mo, 0.6% of Si, 0.02% of Nb, 0.0052% of P, 0.0053% of S, 0.5% of Cr, 0.020% of Ti, and the balance of Fe.
The manufacturing method of the steel rod body for the KD-level surface aluminized modified sucker rod comprises the following steps of carrying out converter smelting, external refining and casting on the components according to the weight percentage to obtain a rod blank, and heating the rod blank to 1200 ℃ through a heating furnace; then rolling by a continuous rolling unit, wherein the starting temperature of the continuous rolling unit is controlled to be 1150 ℃, and the finishing temperature is controlled to be 800 ℃; air cooling to 430 ℃, stacking, preserving heat and slowly cooling for 24 hours; carrying out rapid aluminizing surface treatment on the rod body by high-frequency induction aluminizing equipment, wherein the aluminizing temperature is 720 ℃, and the aluminizing time is 7 min; air cooling to 430 ℃, stacking, preserving heat and slowly cooling for 24 h.
The mechanical properties of the steel rod body manufactured by the method are 595MPa of yield strength, 808MPa of tensile strength and 20% of elongation. The performance index of the special high-strength high-toughness high-strength steel completely meets the requirement of API SPEC 11B on the performance of KD-level steel for sucker rods. The metallographic structure of this example is fine grained bainite, see fig. 3.
Example 4
A KD-grade surface aluminized modified steel for a sucker rod comprises the following chemical components in percentage by weight: 0.08% of C, 2.49% of Mn, 0.3% of Mo, 0.03% of Nb, 0.4% of Si, 0.0053% of P, 0.0038% of S, 1.0% of Cr, 0.020% of Ti, and the balance of Fe.
The manufacturing method of the steel rod body for the KD-level surface aluminized modified sucker rod comprises the following steps of carrying out converter smelting, external refining and casting on the components according to the weight percentage to obtain a rod blank, and heating the rod blank to 1190 ℃ through a heating furnace; then rolling by a continuous rolling unit, wherein the starting temperature of the continuous rolling unit is controlled to be 1140 ℃, and the final rolling temperature is controlled to be 790 ℃; air cooling to 420 ℃, stacking, preserving heat and slowly cooling for 24 hours; carrying out rapid aluminizing surface treatment on the rod body by high-frequency induction aluminizing equipment, wherein the aluminizing temperature is 730 ℃, and the aluminizing time is 5 min; air cooling to 420 ℃, stacking, preserving heat and slowly cooling for 24 h.
Example 5
A KD-grade surface aluminized modified steel for a sucker rod comprises the following chemical components in percentage by weight: 0.08% of C, 2.49% of Mn, 0.3% of Mo, 0.02% of Nb, 0.5% of Si, 0.0053% of P, 0.0038% of S, 1.0% of Cr, 0.020% of Ti, and the balance of Fe.
The manufacturing method of the steel rod body for the KD-level surface aluminized modified sucker rod comprises the following steps of carrying out converter smelting, external refining and casting on the components according to the weight percentage to obtain a rod blank, and heating the rod blank to 1185 ℃ through a heating furnace; then rolling by a continuous rolling unit, wherein the starting temperature of the continuous rolling unit is 1132 ℃, and the finishing temperature is 785 ℃; air cooling to 410 ℃, stacking, preserving heat and slowly cooling for 24 hours; performing rapid aluminizing surface treatment on the rod body by high-frequency induction aluminizing equipment, wherein the aluminizing temperature is 725 ℃, and the aluminizing time is 6 min; air cooling to 440 ℃, stacking, preserving heat and slowly cooling for 24 h.
The steel for the KD-level surface aluminizing modified sucker rod is designed according to the concept that a structure mainly comprising fine granular bainite is obtained by adding low-C and proper-amount Mn into Cr, trace Ti, Nb and other microalloy elements and combining a slow cooling process, so that the sucker rod steel is guaranteed to have excellent mechanical properties.
Compared with the components of the prior sucker rod steel, the invention has the advantages that the alloy formula has lower C content (0.05-0.08%), certain Cr content (0.5-1.0%), certain Mo content (0.25-0.30%), certain Si content (0.3-0.6%), trace Nb (0.02-0.04%) and trace Ti (less than or equal to 0.020%), no elements such as Ni, Cu and the like are added, the component design is simple, and the cost is lower; the appropriate Mn (2.36-2.49%) content makes full use of the phase change strengthening and solid solution strengthening effects of Mn elements; the components are matched with a slow cooling process after hot rolling, so that the comprehensive performance of the product is improved, a flexible hot rolling production process can be adopted, and the productivity is improved. In addition, the product produced by the low C content has high strength, and simultaneously keeps good toughness, plasticity, corrosion resistance and fatigue resistance, so that the sucker rod steel has good crack arrest capability, and the service life of the sucker rod is prolonged manyfold.
Particularly, after the surface aluminizing modification treatment, the rod body is subjected to the slow cooling process after air cooling, and quenching and tempering are not needed, so that the mechanical property requirement is met, more importantly, the organization structure of the aluminized layer is protected, the corrosion resistance of the sucker rod material is obviously improved, and the problems that the structure of the aluminized layer on the surface of the rod body is damaged and the surface corrosion resistance is reduced due to the fact that quenching and tempering are needed again after the surface aluminizing modification treatment in the prior art are solved.
The steel produced by the invention is a fine grained bainite structure, completely meets the requirements of SY5029 standard on the performance of the steel for the KD-grade sucker rod, and can reduce the production and manufacturing cost and increase the production manufacturability.
The performance of the steel for the sucker rod produced by the manufacturing method can meet the following requirements:
(1) tensile properties, target: rm＝795～965MPa，ReL≧590MPa，A≧10％；
(2) And a metallographic structure mainly comprising a fine grained bainite structure.
Referring to table 1, table 1 shows the difference in chemical composition between the steel of the present invention and the steel described in the prior patent documents.
Table 1 comparison of the chemical composition of the inventive steels with the prior art
Compared with patent document 1, the content of C in the components of the invention is remarkably reduced, and the steel-making process is simplified and the cost is reduced by mainly using C, Mn, Cr and Si elements, adding a small amount of alloy elements such as Nb and Ti and not adding alloy elements such as Ni, Cu and V.
Compared with patent documents 2, 3 and 4, the invention reduces the content of C, improves the content of Mn, adds Cr and Mo elements, aims to improve the stability and hardenability of metastable austenite, increase the supercooling capability of austenite, delay the transformation of ferrite and pearlite, promote the gradual right shift of a C curve, delay the transformation of bainite, avoid the high-temperature structure transformation in the process of aluminizing, and further obtain more structures with fine granular bainite as a main structure in the process of aluminizing cooling, thereby ensuring that the alloy has excellent mechanical property and corrosion resistance after aluminizing.
Finally, it should be noted that the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to examples, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.
Claims (4)
1. The steel for the KD-grade surface aluminized modified sucker rod is characterized by comprising the following components in percentage by weight: c: 0.05-0.08%, Mn: 2.36-2.49%, Cr: 0.5 to 1.0%, Mo: 0.25 to 0.30%, Si: 0.30-0.40%, Nb: 0.02-0.04%, S: less than or equal to 0.03%, P: less than or equal to 0.03 percent, Ti: less than or equal to 0.020%, and the balance of iron and inevitable impurities.
2. The steel for KD-grade surface aluminized modified sucker rods according to claim 1, characterized in that the composition thereof comprises, in weight percent: c: 0.05 to 0.07%, Mn: 2.36-2.4%, Cr: 0.8-1.0%, Mo: 0.25 to 0.30%, Si: 0.30-0.40%, Nb: 0.03-0.04%, S: less than or equal to 0.03%, P: less than or equal to 0.03 percent, Ti: less than or equal to 0.020%, and the balance of iron and inevitable impurities.
3. The steel for KD-grade surface aluminized modified sucker rods according to claim 1, characterized in that the composition thereof comprises, in weight percent: c: 0.07 to 0.08%, Mn: 2.4-2.49%, Cr: 0.5-0.8%, Mo: 0.25 to 0.30%, Si: 0.30-0.40%, Nb: 0.02-0.03%, S: less than or equal to 0.03%, P: less than or equal to 0.03 percent, Ti: less than or equal to 0.020%, and the balance of iron and inevitable impurities.
4. A manufacturing method of a KD-level surface aluminized modified sucker rod is characterized by comprising the following steps:
1) c, according to weight percentage: 0.05-0.08%, Mn: 2.36-2.49%, Cr: 0.5 to 1.0%, Mo: 0.25 to 0.30%, Si: 0.30-0.40%, Nb: 0.02-0.04%, S: less than or equal to 0.03%, P: less than or equal to 0.03 percent, Ti: less than or equal to 0.020 percent, and the balance of iron and inevitable impurities, and smelting, refining outside the furnace and casting in a converter or an electric furnace to prepare a bar blank;
2) heating the bar blank to 1180-1200 ℃ in a heating furnace;
3) rolling by a continuous rolling mill set, wherein the starting temperature of the rolling by the continuous rolling mill set is 1130-1150 ℃, and the finishing temperature is 780-800 ℃;
4) slowly cooling after air cooling; wherein the slow cooling starting temperature is 400-450 ℃, and the slow cooling heat preservation time is 24 hours;
5) carrying out rapid aluminizing surface treatment on the rod body in high-frequency induction aluminizing equipment, wherein the aluminizing temperature is 720-740 ℃, and the aluminizing time is 5-10 min;
6) slowly cooling after air cooling; wherein the slow cooling starting temperature is 400-450 ℃, and the slow cooling heat preservation time is 24 h.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101187295A (en) * | 2006-11-21 | 2008-05-28 | 安东石油技术（集团）有限公司 | Super high intensity anti-corrosion pumping rod production method |
| CN101440461A (en) * | 2007-11-21 | 2009-05-27 | 宝山钢铁股份有限公司 | Casinghead gas corrosion resistant pumping rod steel and manufacturing method thereof |
| CN105369149A (en) * | 2015-12-04 | 2016-03-02 | 中国石油天然气集团公司 | Steel for H-level surface aluminizing modified sucker rod and manufacturing method of rod body of sucker rod |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101187295A (en) * | 2006-11-21 | 2008-05-28 | 安东石油技术（集团）有限公司 | Super high intensity anti-corrosion pumping rod production method |
| CN101440461A (en) * | 2007-11-21 | 2009-05-27 | 宝山钢铁股份有限公司 | Casinghead gas corrosion resistant pumping rod steel and manufacturing method thereof |
| CN105369149A (en) * | 2015-12-04 | 2016-03-02 | 中国石油天然气集团公司 | Steel for H-level surface aluminizing modified sucker rod and manufacturing method of rod body of sucker rod |
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