CN115647033A

CN115647033A - Production method of right-handed equal-strength anchor rod reinforcing steel bar MG400Y

Info

Publication number: CN115647033A
Application number: CN202210913698.0A
Authority: CN
Inventors: 陈海军; 雷洪
Original assignee: Xinjiang Bayi Iron and Steel Co Ltd
Current assignee: Xinjiang Bayi Iron and Steel Co Ltd
Priority date: 2023-01-03
Filing date: 2023-01-03
Publication date: 2023-01-31

Abstract

The invention discloses a production method of a right-handed equal-strength anchor rod reinforcing steel bar MG400Y, which is characterized in that HRB400 is used for reference, C strengthening is used as a basis, and V-N alloy is added into the components for microalloying, so that the mechanical property requirement of MG400Y is met; and (3) considering subsequent processing requirements, designing accurate appearance size parameters, determining a hot rolling process by referring to HRB400, designing secondary hole pattern parameters of each frame of the small continuous rolling line, and producing the right-handed and equal-strength anchor rod steel bar with the yield strength of 400MPa which meets the requirements of MT 146.2-2011.

Description

Production method of right-handed equal-strength anchor rod reinforcing steel bar MG400Y

Technical Field

The invention relates to a production method of a right-handed equal-strength anchor rod reinforcing steel bar MG400Y.

Background

The right-handed equal-strength anchor rod reinforcing steel bar MG400Y is MT146.2-2011 resin anchor rod part 2: the metal rod body and the accessory thereof are the raw materials of the metal rod body of the right-handed equi-strength deformed steel bar type resin anchor rod specified in the clause 3.3. MT146.2-2011 part 2 of resin anchor: the metal rod body and its accessories define three shapes of resin anchor rod metal rod body. The innovation is made according to the equal-strength deformed steel bar type resin anchor rod metal rod body specified by MT 146.2-2011. In MT146.2-2011, the finish-rolled right-handed full-thread steel bar with the yield strength not less than 335MPa can be selected as required for the deformed steel bar type metal bar body.

In the MT146.2-2011 standard, only the tensile strength and the yield strength of the right-handed equal-strength anchor rod steel are required to meet the GB1499.2 specification, the tensile strength of a metal rod body of the equal-strength anchor rod with the yield strength of 400MPa is required to be not less than 540MPa, the yield strength is required to be not less than 400MPa, and the elongation of the rod body material after fracture is not less than 15%; the appearance size is required by enterprises, and the full length of the nut can be screwed. The components are not specifically defined.

YB/T4364-2014 Hot rolled ribbed bar for anchor rods specifies the appearance dimension requirements on the thread rib bar (namely the equal-strength anchor rod body in MT 146.2-2011) in appendix A, and does not specify the components and performance requirements. The nominal size and the deviation of the base circle of the steel bar specified by the standard are large, and when the base circle of the rod body is actually controlled to be a positive deviation, the nut is difficult to screw. The height deviation of the thread cross rib specified by the standard is too large, and if the lower limit of the deviation is reached, the requirement that the bearing efficiency coefficient of the nut assembly specified by MT146.2 is more than or equal to 0.95 is difficult to meet. The standard does not specify the helix angle of the thread and specifies that the cross rib tip clearance is no more than 20% of the circumference. This requirement makes it difficult to fill the cross rib at high rolling speeds.

The requirements of the external dimensions of two full-thread equal-strength anchor rods with the specifications of phi 20mm and phi 22mm are introduced in the 2 nd period of volume 21 in 2002, 4 th month and 4 nd month of university of Liaoning engineering technology (Nature science edition) of Cai Guibao, zhang Jun and Fang Zhong, wherein the specification of phi 20mm (Tr 20 in the text) requires the base circle dimension phi 18.5mm; Φ 22mm (Tr 22 herein) requires a base circle size Φ 20.5mm, a pitch of 12mm, no provision for thread specific size, direction, composition, performance and rolling parameter requirements, and no mention of strength rating of full threads.

Zhao Yu, fan Yinping, xi, wang Xiao Yan in Henan Metallurgical (Henan Metallurgical) No. 10, no. 18, no. 5, research and development of strong anchor rod reinforcing steel bars such as Angang right-handed screw rod, provides a size requirement of MG335Y phi 20mm with a yield strength of 335MPa grade: the nominal inner diameter phi is 19mm +/-0.3 mm, the height of a transverse rib is 1.7mm (+ 0.3 to-0.2), the sizes of two sides of a reinforcing steel bar are 18 to 19.3mm, and the thread space is 12mm +/-0.4 mm; the thread turning angle and the transverse rib angle are not required, small square billets of 120mm multiplied by 120mm are adopted for rolling, and rolling parameters are not provided. The MG400Y component, properties and rolling requirements are not involved.

The Huyongling and Liuzhang provides a phi 20mm constant strength anchor rod with yield strength of 335MPa grade in the roll 20, the 1 st period of the roll 20, the 2003 of the Heng Rolling Mill, a 60mm square billet and a phi 250mm 4 transverse rolling mill are adopted for rolling, the inner diameter of a base circle phi is 20mm 0-0.5, the thread pitch is 10mm, the height of a transverse rib is 1.5mm +/-0.2 mm, and the helical angle is 80 degrees. The base circle has a larger inner diameter with the mark HRB335, and does not relate to the components, performance and rolling requirements of MG400Y.

The right-handed equal-strength anchor rod reinforcing steel bar requires that the whole length of the anchor rod reinforcing steel bar can be provided with a nut, and the size precision of a transverse rib, a spiral line (namely a thread turning angle), the thread pitch of the transverse rib, the size and the precision of a base circle influence the screwing of the nut. MT146.2-2011 requires that the bearing efficiency coefficient of the equal-strength anchor rod nut assembly part is more than or equal to 0.95, and the steel bar transverse rib needs to have a certain height to ensure the area of the side surface of the transverse rib. The components and the appearance size of the MG400Y right-handed equi-strength anchor rod steel need to be designed in consideration of safety and accurate control.

The right-handed equal strength anchor bar MG400Y generally has a smaller base circle size than the HRB400 bar. The small size of the base circle has an influence on the strength of the steel bar. MG400Y strength was reduced or not by rolling with HRB400 ingredient directly. Therefore, in the component design, it is necessary to improve the strength and control the cost on the basis of the HRB 400. In order to ensure safety, certain plasticity and toughness are required, and the elongation index needs to be improved.

Disclosure of Invention

The invention aims to provide a production method of a right-handed equal-strength anchor rod reinforcing steel bar MG400Y, which determines rolling requirements and rolling mill pass hole pattern design through designing reasonable components, performance and appearance size parameters, so that the produced MG400Y meets the requirements of MT146.2-2011 on a right-handed equal-strength anchor rod metal rod body with the yield strength of 400 MPa.

The purpose of the invention is realized by the following steps: a production method of right-handed equal-strength anchor rod reinforcing steel bars MG400Y comprises the following steps of 1) process flow: smelting in an electric furnace or a converter, LF refining, continuous casting, 150mm multiplied by 150mm continuous casting square billets meeting the following component requirements, rolling by a small continuous rolling unit, and inspecting, wherein the continuous casting square billets comprise the following components in percentage by mass: 0.22-0.26, si:0.40-0.60, mn:1.35-1.55, P: less than or equal to 0.045, S: less than or equal to 0.045 and V:0.035-0.050; the balance of iron and impurities;

2) And the rolling requirements of the small continuous rolling mill set are as follows: the initial rolling temperature is 1020-1060 ℃, the temperature of the upper cooling bed is less than or equal to 980 ℃, and the metallographic structure of the steel is mainly ferrite and pearlite; the appearance size is controlled by the hole type of each rolling mill and related parameters, and the control is executed according to the requirements of the following table;

；

3) And the parameters of a mill with the specification of phi 18mm,

by using HRB400 for reference, and based on C strengthening, V-N alloy is added into the components for microalloying to meet the mechanical property requirement of MG 400Y; and (3) considering subsequent processing requirements, designing accurate appearance size parameters, determining a hot rolling process by referring to HRB400, designing secondary hole pattern parameters of each frame of the small continuous rolling line, and producing the right-handed and equal-strength anchor rod steel bar with the yield strength of 400MPa which meets the requirements of MT 146.2-2011.

The theoretical basis of the invention is as follows: the strength of hot-rolled steel increases as the content of C in the steel composition increases, and C is the most effective element for improving the strength of steel. The right-handed equal-strength anchor rod reinforcing steel bar MG400Y is the same as the hot-rolled ribbed reinforcing steel bar, and the nominal size is used as the calculation basis when the strength detection is performed. The base circle of the steel has small size, and components contributing to the strength must be higher than HRB400 so as to ensure that the performance of the steel is qualified. HRB400 needs welding in subsequent use, so there is an upper limit requirement for carbon equivalent in component design, MG400Y mainly bears axial force, does not need welding, and strength can be realized by carbon extraction. However, MG400Y, as a safety assurance member, requires a certain plasticity. The plasticity of the steel decreases with increasing carbon content, so the carbon content cannot be too high. In the component design, V-N alloy is added, V microalloying production technology is adopted, and V precipitation and fine grain strengthening effects are utilized to improve the strength and reduce the plasticity reduced by carbon extraction. The cold bending property can reflect the toughness and the internal quality of steel, MT146.2-2011 does not stipulate cold bending detection on the right-handed equi-strength anchor rod steel, and cold bending detection indexes are increased for ensuring safety in the invention.

The difference between the design content and HRB400 and YB/T4364-2014 MG400 in GB/T499.2-2018

The components are as follows:

the difference is as follows: (1) The content ranges of Si and Mn of the MG400Y anchor rod steel are within two standard ranges, but the content ranges are more accurate; the content of C is higher than HRB400 and lower than MG400, which can not only exert the contribution of C to strength, but also improve the ductility and toughness together with V; the contents of P and S are higher than the MG400 requirement in YB/T4364-2014, so that the smelting difficulty is reduced; (2) The V-N alloy is added to improve the strength and plasticity through V microalloying, so that the use safety of the anchor rod is met.

The dimensions and tolerances are shown in table 2:

TABLE 2

The main differences are as follows: (1) The YB/T4364 thread rib anchor rod steel bar does not have the requirement of phi 16mm and does not have the requirement of thread turning angle (namely, the lead angle in the table 2); (2) The YB/T4364 threaded rib anchor rod reinforcing steel bar requires that the sum of the gaps of the tail ends of transverse ribs is not more than 20 percent of the nominal perimeter; the bearing efficiency coefficient of an anchor rod nut assembly part is considered to ensure the requirement of the height of the transverse rib, and the requirement on the tail end gap is not provided; (3) The internal diameter of MG400Y is smaller than the requirement of YB/T4364, the allowable deviation range of the internal diameter is narrower than the requirement of YB/T4364, and the screwing of the nut is more favorably ensured when the anchor rod is used; (4) The allowable deviation range of the height of the MG400Y transverse rib and the allowable deviation range of the bottom width of the transverse rib are narrower than the requirements of YB/T4364, the size is more accurate, and the use safety of the anchor rod is facilitated; (5) The MG400Y pitch deviation is symmetrical deviation, and the YB/T4364 pitch deviation is unidirectional negative deviation; (6) The root of the MG400Y transverse rib of the invention stipulates the arc radius, requires the arc transition of the thread root, can lighten the stress concentration of the thread root when in use and improves the safety;

the mechanical properties are designed and shown in Table 3

TABLE 3 mechanical Properties

Description of the drawings: YB/T4364 stipulates the requirements of mechanical property and bending property of the reinforcing steel bar for the anchor rod reinforcing steel bar, and the mark is MG400. The composition and meaning of the designations defined in this standard should not include MG400Y. Even compared with the standard MG400, the tensile strength and yield strength indexes of the MG400Y of the invention are 20MPa higher than those of the MG400 off-line, and the use is safer. Compared with MT146.2-2011, the elongation index is higher, the bending property is improved, and the requirement on the plastic toughness of the steel bar is improved, so that the anchor rod can bear impact load more favorably.

Drawings

Fig. 1 is a design drawing of the external dimensions of the steel bar of the present invention.

Detailed Description

The invention is realized by the following modes: a production method of right-handed equal-strength anchor rod reinforcing steel bar MG400Y,

1) And the process flow is as follows: smelting in an electric furnace or a converter, LF refining, continuous casting, 150mm multiplied by 150mm continuous casting square billets meeting the following component requirements, rolling by a small continuous rolling mill set, and inspecting, wherein the component comprises the following components in percentage by mass: 0.22-0.26, si:0.40-0.60, mn:1.35-1.55, P: less than or equal to 0.045, S: less than or equal to 0.045 and V:0.035-0.050;

2) And the rolling requirements of the small continuous rolling mill group are as follows: the initial rolling temperature is 1020-1060 ℃, the temperature of the upper cooling bed is less than or equal to 980 ℃, and the metallographic structure of the steel is mainly ferrite and pearlite; the appearance size is controlled by the hole type of each rolling mill and related parameters, and the control is executed according to the requirements of the following table 5;

the invention provides three rolling mill parameters of phi 18mm, phi 20mm and phi 22mm, and phi 16mm and phi 25mm can be determined according to the invention.

TABLE 6 rolling mill parameters of 18mm phi

Table 7 mill parameters of 20mm phi;

TABLE 8 phi 22mm rolling mill parameters

The produced product has a diameter of 18mm, 20mm and 22mm, and the appearance sizes of the performance components meet the design requirements, as shown in figure 1. The data of each specification sampling test are shown in tables 9, 10 and 11,

the invention is suitable for producing the right-handed equistrength anchor rod steel MG400Y with the yield strength of 400MPa grade by using a 150mm multiplied by 150mm continuous casting square billet smelted by an electric furnace or a converter and a small continuous rolling mill set.

Claims

1. A production method of right-handed equal-strength anchor rod reinforcing steel bars MG400Y is characterized in that:

1) And the process flow is as follows: smelting in an electric furnace or a converter, LF refining, continuous casting, 150mm multiplied by 150mm continuous casting square billets meeting the following component requirements, rolling by a small continuous rolling mill set, and inspecting, wherein the continuous casting square billets comprise the following components in percentage by mass percent: 0.22-0.26, si:0.40-0.60, mn:1.35-1.55, P: less than or equal to 0.045, S: less than or equal to 0.045 and V:0.035 to 0.050; the balance of iron and impurities;

2) And the rolling requirements of the small continuous rolling mill group are as follows: the initial rolling temperature is 1020-1060 ℃, the temperature of the upper cooling bed is less than or equal to 980 ℃, and the metallographic structure of the steel is mainly ferrite and pearlite; the appearance size is controlled by the hole type of each rolling mill and related parameters, and the control is executed according to the requirements of the following table;

3) And the parameters of a mill with the specification of phi 18mm,

。