CN112695244B - Low-carbon equivalent easy-welding Q690D steel plate for engineering machinery and production method thereof - Google Patents

Low-carbon equivalent easy-welding Q690D steel plate for engineering machinery and production method thereof Download PDF

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CN112695244B
CN112695244B CN202011388571.9A CN202011388571A CN112695244B CN 112695244 B CN112695244 B CN 112695244B CN 202011388571 A CN202011388571 A CN 202011388571A CN 112695244 B CN112695244 B CN 112695244B
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CN112695244A (en
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杨浩
孙电强
杜琦铭
陈振业
王会岭
赵燕青
魏浩
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HBIS Co Ltd
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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
    • 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
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • 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
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • 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
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
    • 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
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • 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
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • 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
    • 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
    • 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
    • C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)

Abstract

A low-carbon equivalent easy-welding Q690D steel plate for engineering machinery and a production method thereof belong to the technical field of metallurgy. The steel plate comprises the following chemical components in percentage by weight: 0.06-0.08%, Si: 0.20 to 0.30%, Mn: 1.10-1.35%, P is less than or equal to 0.02%, S is less than or equal to 0.01%, Cr: 0.20 to 0.35%, Nb: 0.02 to 0.03%, Ti: 0.009-0.02%, Als: 0.02-0.04%, B: 0.0012-0.0015%, and the balance of Fe and inevitable impurities; the steel plate Ceq is less than 0.4, and Pcm is less than 0.2. The production method comprises the working procedures of heating, rolling, direct quenching after rolling and tempering; the final cooling temperature of the quenching procedure is less than or equal to 200 ℃. The invention ensures that the strength and the low-temperature toughness meet the requirements under the conditions of low carbon equivalent and low welding crack sensitivity index.

Description

Low-carbon equivalent easy-welding Q690D steel plate for engineering machinery and production method thereof
Technical Field
The invention belongs to the technical field of metallurgy, and particularly relates to a low-carbon equivalent easy-welding Q690D steel plate for engineering machinery and a production method thereof.
Background
The high-strength steel of grade Q690D is mainly used for manufacturing main parts of equipment such as excavating machinery, construction hoisting machinery, mining machinery, industrial vehicles and the like. With the development of large-scale and intensive engineering machinery, the proportion of 690 MPa-yield strength and even higher-strength-grade steel in engineering machinery equipment is larger and larger, and the requirement on Q690-grade high-strength steel is higher and higher, so that the high-strength-grade steel is required to have stable mechanical properties and also have higher requirements on welding performance. At present, in the production process of the coal mine hydraulic support, Q550D does not need to be preheated before welding, but Q690D still needs to be preheated to ensure the welding performance and quality. Preheating before welding not only prolongs the production process, but also increases the production cost. Therefore, it is urgently required to develop Q690D steel which does not require pre-weld preheating.
Disclosure of Invention
In order to solve the technical problems, the invention provides a low-carbon equivalent easy-welding Q690D steel plate for engineering machinery and a production method thereof. The strength and the low-temperature impact toughness of the steel plate meet the requirements of Q690D under the conditions of low carbon equivalent and low weld crack sensitivity index. The invention adopts the following technical scheme:
a low-carbon equivalent easy-welding Q690D steel plate for engineering machinery comprises the following chemical components in percentage by mass: 0.06-0.08%, Si: 0.20 to 0.30%, Mn: 1.10-1.35%, P is less than or equal to 0.02%, S is less than or equal to 0.01%, Cr: 0.20 to 0.35%, Nb: 0.02 to 0.03%, Ti: 0.009-0.02%, Als: 0.02-0.04%, B: 0.0012-0.0015%, and the balance of Fe and inevitable impurities; the carbon equivalent Ceq of the steel plate is less than 0.4, and the welding crack sensitivity index Pcm is less than 0.2;
wherein Ceq = C + Mn/6+ (Cr + Mo + V)/5+ (Cu + Ni)/15; pcm = C + Si/30+ (Mn + Cu + Cr)/20+ Ni/60+ Mo/15+ V/10+ 5B.
The thickness of the steel plate is 20-40 mm, and the steel plate structure is tempered martensite and bainite; the yield strength of the steel plate is more than or equal to 750MPa, the tensile strength is more than or equal to 830MPa, the elongation is more than or equal to 17 percent, and the transverse impact energy at the temperature of minus 20 ℃ is more than or equal to 200J.
The production method of the low-carbon equivalent easy-welding Q690D steel plate for the engineering machinery comprises the working procedures of heating, rolling, quenching and tempering.
In the heating procedure, the heating temperature is 1180-1220 ℃, and the total heating time is more than 10 min/mm.
In the rolling procedure, the first stage is a rough rolling stage, and the initial rolling temperature is 1050-1150 ℃; the second stage is a finish rolling stage, the initial rolling temperature is less than or equal to 950 ℃, and the final rolling temperature is controlled to be 800-830 ℃.
The quenching process adopts direct quenching after rolling, the initial cooling temperature is more than or equal to 780 ℃, the final cooling temperature is less than or equal to 200 ℃, and the cooling speed is more than or equal to 20 ℃/s.
In the tempering process, a tempering furnace is adopted for tempering, the heating temperature is 520-550 ℃, the heat preservation coefficient is 3-3.5 min/mm, and the steel plate is discharged from the furnace and then cooled in air.
The design idea of the invention is as follows:
carbon equivalent and weld crack sensitivity index are the most direct factors affecting the welding process. Studies have shown that when the carbon equivalent is below 0.4 and the weld crack sensitivity index is below 0.2, no preheating may be performed prior to welding. The lower carbon equivalent can improve the weldability, but reduces the hardenability of the steel, which is not favorable for improving the strength of the steel sheet. The hardenability of the steel can be obviously improved by adding a certain amount of Cr in the steel grade, and meanwhile, the Cr can also play a role in improving the strength. The hardenability of the steel can be obviously improved by adding a trace amount of boron (0.0005-0.005%) into the steel, and at the moment, the hardenability of the steel has no influence or little influence on other properties and the like, and good impact toughness can be obtained after quenching and low-temperature tempering. The invention adopts the concept of low-carbon content microalloying, adds a proper amount of Cr and B elements, improves the hardenability of steel, and fully utilizes the controlled cooling process and the quenching and tempering heat treatment process after rolling to ensure that a steel plate obtains a tempered martensite + bainite structure, and has good mechanical property and welding property.
The carbon equivalent Ceq of the steel plate is less than 0.4, and the welding crack sensitivity index Pcm is less than 0.2; the thickness of the steel plate is 20-40 mm, the yield strength is more than or equal to 750MPa, the tensile strength is more than or equal to 830MPa, the elongation is more than or equal to 17%, and the transverse impact energy at minus 20 ℃ is more than or equal to 200J. Under the conditions of low carbon equivalent and low weld crack sensitivity index, the strength and low-temperature impact toughness of the steel plate meet the requirements of Q690D, pre-welding preheating is not needed in the process of preparing engineering mechanical parts, the welding performance and quality of the steel plate can be ensured, and the production process of downstream enterprises is shortened.
Drawings
FIG. 1 is a typical metallographic structure of a steel sheet according to example 1 of the present invention.
Detailed Description
The present invention will be described in further detail with reference to examples.
Examples 1 to 10
A production method of a low-carbon equivalent easy-welding Q690D steel plate for engineering machinery mainly comprises the working procedures of heating, rolling, quenching and tempering.
And heating, wherein the heating temperature is 1180-1220 ℃, and the total heating time is more than 10 min/mm.
A rolling procedure, wherein the first stage is a rough rolling stage, and the initial rolling temperature is 1050-1150 ℃; the second stage is a finish rolling stage, the initial rolling temperature is less than or equal to 950 ℃, and the final rolling temperature is controlled to be 800-830 ℃.
The quenching process adopts direct quenching after rolling, wherein the initial cooling temperature is more than or equal to 780 ℃, the final cooling temperature is less than or equal to 200 ℃, and the cooling speed is more than or equal to 20 ℃/s.
And a tempering step, tempering by adopting a tempering furnace, heating at 520-550 ℃, keeping the temperature coefficient at 3-3.5 min/mm, and air cooling after discharging.
The continuous casting billets with the thickness of 260mm are adopted in each embodiment, the production process parameters are shown in table 1, the chemical components and the mass percentage content of the obtained steel plate are shown in table 2, and the specification and the performance of the steel plate are shown in table 3.
TABLE 1 production Process parameters for the examples
Figure DEST_PATH_IMAGE002
Table 2 chemical composition and mass% of steel sheet for each example
Figure DEST_PATH_IMAGE004
TABLE 3 Steel plate specification and Properties of examples
Figure DEST_PATH_IMAGE006
。

Claims (4)

1. The low-carbon equivalent easy-welding Q690D steel plate for engineering machinery is characterized by comprising the following chemical components in percentage by mass: 0.06-0.08%, Si: 0.20 to 0.30%, Mn: 1.10-1.35%, P is less than or equal to 0.02%, S is less than or equal to 0.01%, Cr: 0.20 to 0.35%, Nb: 0.02 to 0.03%, Ti: 0.009-0.02%, Als: 0.02-0.04%, B: 0.0012-0.0015%, and the balance of Fe and inevitable impurities; the carbon equivalent Ceq of the steel plate is less than 0.4, and the welding crack sensitivity index Pcm is less than 0.2;
the steel sheet is produced by a method comprising heating, rolling, quenching and tempering processes; in the heating procedure, the heating temperature is 1180-1220 ℃, and the total heating time is more than 10 min/mm; in the rolling procedure, the first stage is a rough rolling stage, and the initial rolling temperature is 1050-1150 ℃; the second stage is a finish rolling stage, wherein the initial rolling temperature is less than or equal to 950 ℃, and the final rolling temperature is controlled to be 800-830 ℃; the quenching process adopts direct quenching after rolling, wherein the start cooling temperature is more than or equal to 780 ℃, the final cooling temperature is less than or equal to 200 ℃, and the cooling speed is more than or equal to 20 ℃/s; in the tempering process, a tempering furnace is adopted for tempering, the heating temperature is 520-550 ℃, the heat preservation coefficient is 3-3.5 min/mm, and the steel plate is discharged from the furnace and then cooled in air.
2. The low-carbon equivalent easy-welding Q690D steel plate for engineering machinery as claimed in claim 1, wherein the steel plate has a thickness of 20-40 mm and a steel plate structure of tempered martensite + bainite.
3. The steel plate for the low-carbon equivalent easy-welding Q690D engineering machinery, as claimed in claim 1 or 2, wherein the steel plate has a yield strength of 750MPa or more, a tensile strength of 830MPa or more, an elongation of 17% or more, and a transverse impact energy of 200J or more at-20 ℃.
4. The production method of the low carbon equivalent easy-welding Q690D steel plate for engineering machinery, which is based on any one of claims 1-3, is characterized by comprising the steps of heating, rolling, quenching and tempering;
in the heating procedure, the heating temperature is 1180-1220 ℃, and the total heating time is more than 10 min/mm;
in the rolling procedure, the first stage is a rough rolling stage, and the initial rolling temperature is 1050-1150 ℃; the second stage is a finish rolling stage, wherein the initial rolling temperature is less than or equal to 950 ℃, and the final rolling temperature is controlled to be 800-830 ℃;
the quenching process adopts direct quenching after rolling, wherein the start cooling temperature is more than or equal to 780 ℃, the final cooling temperature is less than or equal to 200 ℃, and the cooling speed is more than or equal to 20 ℃/s;
in the tempering process, a tempering furnace is adopted for tempering, the heating temperature is 520-550 ℃, the heat preservation coefficient is 3-3.5 min/mm, and the steel plate is discharged from the furnace and then cooled in air.
CN202011388571.9A 2020-12-02 2020-12-02 Low-carbon equivalent easy-welding Q690D steel plate for engineering machinery and production method thereof Active CN112695244B (en)

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103290339A (en) * 2013-06-29 2013-09-11 首钢总公司 High-strength steel plate for 800MPa hydropower station pressure pipeline and production method thereof

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103290339A (en) * 2013-06-29 2013-09-11 首钢总公司 High-strength steel plate for 800MPa hydropower station pressure pipeline and production method thereof

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