TMCP-state Q460ME steel plate with high core impact toughness and preparation method of TMCP-state Q460ME steel plate

Abstract

The invention discloses a TMCP state Q460ME steel plate with high core impact toughness and a preparation method of the TMCP state Q460ME steel plate, and relates to the technical field of steel production, the TMCP state Q460ME steel plate comprises the following chemical components in percentage by mass: 0.05-0.09% of C, 1.45-1.55% of Mn, 0.15-0.25% of Si, 0.030-0.050% of Nb, 0.008-0.015% of Ti, 0.020-0.040% of Alt, 0.15-0.45% of Cr, 0.20-0.60% of Ni, less than or equal to 0.015% of P, less than or equal to 0.004% of S and the balance of iron and inevitable impurities. The TMCP type Q40ME steel plate provided by the invention is reasonable in chemical component design, uniform in internal structure, fine in core structure, less in added noble metal and high in market competitiveness, the grain size of the steel plate reaches more than 8 grades, and the production cost is greatly reduced by adopting TMCP delivery compared with normalizing heat treatment delivery.

Description

Technical Field

[0001] The invention relates to the technical field of steel production, and in particular to a TMCP state Q460ME steel plate with high core impact toughness and a preparation method thereof. Background Art

[0002] Low alloy structural steel is widely used in many fields such as construction, bridges, automobiles and machinery manufacturing. With the development of economy and technological progress, lightweight design and high strength have become important development trends. High-strength Q460 structural steel can still maintain stability when subjected to large loads and complex environments. With the improvement of material performance requirements for key projects such as engineering machinery and marine equipment, core impact toughness has become an important technical indicator.

[0003] At present, the domestically published patents on low-temperature toughness -40℃ impact energy Q460E level mainly include "A high-strength and toughness structural steel Q460E thick plate and its production method" (patent number CN201110176678.1) and "A production method of low yield ratio and high toughness Q460GJ" (patent number CN201911074675.X). The performance of the manufacturing process steel plates in the above patents are all tested according to the standards, and none of them mentions the manufacturing method that guarantees -40℃ core impact. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a TMCP state Q460ME steel plate with high core impact toughness and a preparation method thereof.

[0005] In order to solve the above technical problems, the technical solution of the present invention is as follows: A TMCP state Q460ME steel plate with high core impact toughness, whose chemical composition and mass percentage are as follows: C: 0.05~ 0.09%, Mn: 1.45~ 1.55%, Si: 0.15 ~ 0.25%, Nb: 0.030 ~ 0.050%, Ti: 0.008 ~0.015%, Alt: 0.020 ~ 0.040%, Cr: 0.15~ 0.45%, Ni: 0.20~ 0.60%, P≤0.015%, S≤0.004%, and the balance is iron and unavoidable impurities.

[0006] The present invention also discloses a method for preparing a TMCP state Q460ME steel plate with high core impact toughness, which comprises the following steps in sequence: smelting and continuous casting, heating, and rolling; Among them, the smelting and continuous casting process adopts electromagnetic stirring and light pressure technology, the liquid level of the crystallizer is automatically controlled, the fluctuation range is controlled to ±3mm, the superheat is controlled to 15-20℃, and the strong cooling technology is used at the end of solidification to make the low-multiple center segregation grade of the ingot ≤C grade 1.0.

[0007] As a preferred embodiment of the method for preparing the TMCP state Q460ME steel plate with high core impact toughness described in the present invention, wherein: in the heating process, the ingot is heated in a continuous furnace, and when the furnace temperature T≤580°C, the temperature of the ingot heating soaking section is controlled to be 1230-1250°C, the steel tapping temperature is controlled to be 1190 ~1210°C, and the total heating coefficient is ≥10min / cm.

[0008] As a preferred solution of the method for preparing the TMCP state Q460ME steel plate with high core impact toughness described in the present invention, the rolling process adopts two-stage controlled rolling, including one-stage rolling and two-stage rolling.

[0009] As a preferred solution of the method for preparing the TMCP state Q460ME steel plate with high core impact toughness described in the present invention, wherein: the starting rolling temperature of the one-stage rolling is 1090-1180°C, a high-temperature and high-reduction rolling process is adopted, and the reduction rate in the rough rolling stage is controlled to be greater than 45%.

[0010] As a preferred solution of the method for preparing the TMCP state Q460ME steel plate with high core impact toughness described in the present invention, the starting rolling temperature of the two-stage rolling is 790-850°C, the final rolling temperature is 740-780°C, and the steel plate red-returning temperature is 450-500°C.

[0011] The beneficial effects of the present invention are: (1) The TMCP type Q40ME steel plate provided by the present invention has a reasonable chemical composition design, a uniform internal structure of the steel plate, a fine core structure, a grain size of more than 8 levels, a small amount of precious metals added, and is delivered in the TMCP state, which greatly reduces the production cost compared to delivery by normalizing heat treatment, and has strong market competitiveness.

[0012] (2) The steel plate produced by the present invention has good matching between strength and toughness, with a yield strength of ≥460MPa, a tensile strength of 550-680MPa, and a longitudinal impact energy of -40°C at the V-shaped core of ≥150J.

[0013] (3) The steel plate produced by the present invention has a uniform and dense internal structure, and the thickness specification of the steel plate is 40-60 mm, which meets the technical requirements of -40°C core impact toughness for key projects in the fields of steel structure, construction, engineering machinery, etc., and has broad application prospects. DETAILED DESCRIPTION

[0014] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific implementation methods.

[0015] Example 1: This example provides a TMCP state Q460ME steel plate with high core impact toughness, whose chemical composition and mass percentage are as follows: C: 0.05%, Mn: 1.52%, Si: 0.15%, Nb: 0.037%, Ti: 0.012%, Alt: 0.040%, Cr: 0.45%, Ni: 0.60%, P: 0.015%, S: 0.002%, and the remainder is iron and unavoidable impurities.

[0016] This embodiment also provides a method for preparing a TMCP state Q460ME steel plate with high core impact toughness, which comprises the following steps in sequence: smelting and continuous casting, heating, and rolling.

[0017] Among them, in the smelting and continuous casting stage: a 460mm large-section continuous casting machine is used, the liquid level in the crystallizer is automatically controlled, the liquid level fluctuation is ±3mm, the superheat of the tundish is 18°C, and the strong cooling technology is applied at the end of solidification. The low-multiple center segregation grade of the ingot is Class C 0.5.

[0018] Heating process: The continuous casting billet is heated in a continuous furnace with a furnace temperature of 550°C, a billet soaking zone temperature of 1230°C, a steel tapping temperature of 1198°C, and a total heating coefficient of 12min / cm.

[0019] Rolling process: adopt two-stage controlled rolling process, the first stage rolling temperature is 1095℃, high temperature and large reduction rolling process, the rough rolling stage reduction rate is 48%. The second stage rolling temperature is 790℃, the final rolling temperature is 742℃, and the red-returning temperature is 467℃.

[0020] The thickness of the steel plate obtained in this embodiment is 60 mm. The structure of the steel plate obtained after cooling is bainite + ferrite + a small amount of pearlite, the grain size is 8.5, the yield strength of the steel plate is 469 MPa, the tensile strength is 550 MPa, the longitudinal impact energy of the core at -40°C is 185 J, the comprehensive performance is excellent, it has high toughness impact energy, and stable performance.

[0021] Example 2: This example provides a TMCP state Q460ME steel plate with high core impact toughness, whose chemical composition and mass percentage are as follows: C: 0.09%, Mn: 1.45%, Si: 0.23%, Nb: 0.038%, Ti: 0.015%, Alt: 0.035%, Cr: 0.18%, Ni: 0.28%, P: 0.012%, S: 0.004%, and the remainder is iron and unavoidable impurities.

[0022] This embodiment also provides a method for preparing a TMCP state Q460ME steel plate with high core impact toughness, which comprises the following steps in sequence: smelting and continuous casting, heating, and rolling.

[0023] Among them, in the smelting and continuous casting stage: a 370mm large-section continuous casting machine is used, the liquid level in the crystallizer is automatically controlled, the liquid level fluctuation is ±3mm, the superheat of the tundish is 15°C, and the strong cooling technology is applied at the end of solidification. The low-multiple center segregation grade of the ingot is Class C 1.0.

[0024] Heating process: The continuous casting billet is heated in a continuous furnace with a furnace temperature of 540°C, a billet soaking zone temperature of 1235°C, a steel tapping temperature of 1190°C, and a total heating coefficient of 10 min / cm.

[0025] Rolling process: adopt two-stage controlled rolling process, the first stage rolling temperature is 1180℃, high temperature and large reduction rolling process, the rough rolling stage reduction rate is 45%. The second stage rolling temperature is 850℃, the final rolling temperature is 780℃, and the red-returning temperature is 500℃.

[0026] The steel plate prepared in this embodiment has a thickness of 40 mm. The steel plate structure obtained after cooling is bainite + ferrite + a small amount of pearlite, the grain size is 9.0, the steel plate yield strength is 520 MPa, the tensile strength is 680 MPa, the core longitudinal -40°C impact energy is 176 J, the comprehensive performance is excellent, it has high toughness impact energy, and stable performance.

[0027] Example 3: This example provides a TMCP state Q460ME steel plate with high core impact toughness, whose chemical composition and mass percentage are as follows: C: 0.06%, Mn: 1.55%, Si: 0.25%, Nb: 0.050%, Ti: 0.008%, Alt: 0.020%, Cr: 0.23%, Ni: 0.26%, P: 0.009%, S: 0.001%, and the remainder is iron and unavoidable impurities.

[0028] This embodiment also provides a method for preparing a TMCP state Q460ME steel plate with high core impact toughness, which comprises the following steps in sequence: smelting and continuous casting, heating, and rolling.

[0029] Among them, in the smelting and continuous casting stage: a 370mm large-section continuous casting machine is used, the liquid level in the crystallizer is automatically controlled, the liquid level fluctuation is ±3mm, the superheat of the tundish is 20℃, and the strong cooling technology is applied at the end of solidification. The segregation grade of the low-multiple center of the ingot is Class C 0.5.

[0030] Heating process: The continuous casting billet is heated in a continuous furnace with a furnace temperature of 580°C, a billet soaking section temperature of 1245°C, a steel tapping temperature of 1205°C, and a total heating coefficient of 11min / cm.

[0031] Rolling process: adopt two-stage controlled rolling process, the first stage rolling temperature is 1090℃, high temperature and large reduction rolling process, the rough rolling stage reduction rate is 47%. The second stage rolling temperature is 824℃, the final rolling temperature is 745℃, and the red-returning temperature is 450℃.

[0032] The steel plate prepared in this embodiment has a thickness of 50 mm. The structure of the steel plate obtained after cooling is bainite + ferrite + a small amount of pearlite, the grain size is 8.5, the yield strength of the steel plate is 495 MPa, the tensile strength is 610 MPa, the longitudinal impact energy of the core at -40°C is 244 J, the comprehensive performance is excellent, it has high toughness impact energy, and the performance is stable.

[0033] Example 4: This example provides a TMCP state Q460ME steel plate with high core impact toughness, whose chemical composition and mass percentage are as follows: C: 0.05%, Mn: 1.57%, Si: 0.18%, Nb: 0.030%, Ti: 0.010%, Alt: 0.038%, Cr: 0.15%, Ni: 0.20%, P: 0.011%, S: 0.002%, and the remainder is iron and unavoidable impurities.

[0034] This embodiment also provides a method for preparing a TMCP state Q460ME steel plate with high core impact toughness, which comprises the following steps in sequence: smelting and continuous casting, heating, and rolling.

[0035] Among them, in the smelting and continuous casting stage: a 460mm large-section continuous casting machine is used, the liquid level in the crystallizer is automatically controlled, the liquid level fluctuation is ±3mm, the superheat of the tundish is 17°C, and the strong cooling technology is applied at the end of solidification. The low-multiple center segregation grade of the ingot is Class C 0.5.

[0036] Heating process: The continuous casting billet is heated in a continuous furnace with a furnace temperature of 558°C, a billet soaking zone temperature of 1250°C, a steel tapping temperature of 1210°C, and a total heating coefficient of 13min / cm.

[0037] Rolling process: adopt two-stage controlled rolling process, the first stage rolling temperature is 1180℃, high temperature and large reduction rolling process, the rough rolling stage reduction rate is 47%. The second stage rolling temperature is 815℃, the final rolling temperature is 740℃, and the red-returning temperature is 482℃.

[0038] The thickness of the steel plate obtained in this embodiment is 55 mm. The structure of the steel plate obtained after cooling is bainite + ferrite + a small amount of pearlite, the grain size is 9.5, the yield strength of the steel plate is 502 MPa, the tensile strength is 680 MPa, the longitudinal impact energy of the core at -40°C is 155 J, the comprehensive performance is excellent, it has high toughness impact energy, and stable performance.

[0039] Therefore, the technical solution of the present application has a reasonable chemical composition design, the internal structure of the steel plate is uniform, the core structure is fine, the grain size reaches above level 8, less precious metals are added, and the steel plate is delivered in TMCP state, which greatly reduces the production cost compared with the normalizing heat treatment delivery. The market competitiveness is strong, and the strength and toughness of the steel plate obtained are well matched, the yield strength is ≥460MPa, the tensile strength is 550-680MPa, and the longitudinal -40°C impact energy of the V-shaped core is ≥150J.

[0040] In addition to the above embodiments, the present invention may also have other implementation modes; any technical solutions formed by equivalent replacement or equivalent transformation shall fall within the protection scope required by the present invention.

Claims

1. A TMCP state Q460ME steel plate with high core impact toughness, characterized in that: Its chemical composition and mass percentage are as follows: C: 0.05~ 0.09%, Mn: 1.45~ 1.55%, Si: 0.15 ~ 0.25%, Nb: 0.030 ~ 0.050%, Ti: 0.008~ 0.015%, Alt: 0.020 ~ 0.040%, Cr: 0.15~ 0.45%, Ni: 0.20~ 0.60%, P≤0.015%, S≤0.004%, and the balance is iron and unavoidable impurities.

2. A method for preparing the TMCP state Q460ME steel plate with high core impact toughness according to claim 1, characterized in that: The following processes are included in sequence: smelting and continuous casting, heating, and rolling; Among them, the smelting and continuous casting process adopts electromagnetic stirring and light pressure technology, the liquid level of the crystallizer is automatically controlled, the fluctuation range is controlled to ±3mm, the superheat is controlled to 15-20℃, and the strong cooling technology is used at the end of solidification to make the low-multiple center segregation grade of the ingot ≤C grade 1.

0.

3. The method for preparing the TMCP state Q460ME steel plate with high core impact toughness according to claim 2, characterized in that: In the heating process, the ingot is heated in a continuous furnace. When the furnace temperature T≤580°C, the temperature of the ingot heating soaking section is controlled to be 1230-1250°C, the steel tapping temperature is controlled to be 1190-1210°C, and the total heating coefficient is ≥10min / cm.

4. The method for preparing the TMCP state Q460ME steel plate with high core impact toughness according to claim 2, characterized in that: The rolling process adopts two-stage controlled rolling, including one-stage rolling and two-stage rolling.

5. The method for preparing the TMCP state Q460ME steel plate with high core impact toughness according to claim 4, characterized in that: The starting rolling temperature of the first-stage rolling is 1090-1180° C., and a high-temperature and high-reduction rolling process is adopted, and the reduction rate in the rough rolling stage is controlled to be greater than 45%.

6. The method for preparing the TMCP state Q460ME steel plate with high core impact toughness according to claim 4, characterized in that: The starting rolling temperature of the two-stage rolling is 790-850°C, the final rolling temperature is 740-780°C, and the steel plate red-returning temperature is 450-500°C.