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CN-122012885-A - Preheating-free welded steel plate and production method thereof, and preheating-free welding method

CN122012885ACN 122012885 ACN122012885 ACN 122012885ACN-122012885-A

Abstract

The application discloses a preheating-free welded steel plate, a production method thereof and a preheating-free welding method. The production method comprises the steps of blank making, rolling, cooling, quenching and tempering which are sequentially carried out, wherein in the blank making step, a continuous casting blank is sent into a heat preservation pit for heat preservation, the temperature in the heat preservation pit is 630-670 ℃, the heat preservation time t is larger than or equal to D 2 /40D, D is the thickness of the continuous casting blank, D is the hydrogen diffusion coefficient in the continuous casting blank, in the quenching step, a steel plate is heated and then is kept at the heating temperature of (A c3 -30)℃~(A c3 -10) ° C, the furnace time is (1.5a+20) min to (1.5a+30) min, then the steel plate is rapidly cooled to room temperature, the cooling speed is (V B +15) ℃/s~(V B +20) ° C/s, and in the tempering step, the heating temperature is (Ms-235) ° C to (210) ° C, and the furnace time is (5a+10) min to (5a+30) min.

Inventors

  • ZHAO RONGGUI
  • ZHEN FAN
  • SHAO CHUNJUAN
  • QU JINBO

Assignees

  • 江苏沙钢钢铁有限公司
  • 江苏省沙钢钢铁研究院有限公司

Dates

Publication Date
20260512
Application Date
20260410

Claims (13)

  1. 1. A production method of a steel plate is characterized by comprising the steps of blank making, rolling, cooling, quenching and tempering which are sequentially carried out; In the blank making process, preparing a continuous casting blank, and conveying the continuous casting blank into a heat preservation pit for heat preservation, wherein the temperature in the heat preservation pit is 630-670 ℃, and the heat preservation time t is more than or equal to D 2 /40D in units of s, wherein D is the thickness of the continuous casting blank in units of mm, D is the hydrogen diffusion coefficient in the continuous casting blank in units of mm 2 /s; in the rolling process, the continuous casting billet is heated and rolled into a steel plate; In the cooling step, the steel plate is cooled; In the quenching process, the cooled steel plate is sent into a heating furnace to be heated and then kept at the heating temperature of (A c3 -30)℃~(A c3 -10) DEG C, the furnace time is (1.5a+20) min to (1.5a+30) min, and then the steel plate is quickly cooled to room temperature, wherein the cooling speed is (V B +15) ℃/s~(V B +20) DEG C/s; in the tempering process, the steel plate after the quenching process is sent into a heating furnace to be heated and then kept at the heating temperature of (Ms-235) ° C to (Ms-210) ° C, and the furnace time is (5a+10) min to (5a+30) min; Wherein the austenitizing end temperature a c3 = 912-250C-16mn+48si-2Cr-16ni+95v+96ti+210alt-10Cu; The critical cooling speed V B =e (13.08-8.8C-1.07Mn-0.7Ni-0.57Cr-9.2Mo-366B) /3600 of bainite formation; Martensitic transformation start temperature ms=561-474C-33 Mn-17Cr-17Ni-21Mo; a is the thickness of the steel plate, and the unit is mm.
  2. 2. The method for producing a steel sheet according to claim 1, wherein the chemical composition of the continuous casting slab comprises ：C 0.20~0.23%、Si 0.28~0.36%、Mn 0.90~1.10%、Cr 0.35~0.42%、Ti 0.012~0.019%、Alt 0.021~0.049%、B 0.0016~0.0021%、Zr 0.012~0.019%、Ca 0.0022~0.0052%、N 20~45ppm、O≤15ppm、H≤1.5ppm、P≤0.008%、S≤0.0012%, by mass percent of the balance Fe and unavoidable impurities.
  3. 3. The method for producing the steel plate according to claim 2, wherein the chemical components of the continuous casting blank are as follows in percentage by mass, wherein the carbon equivalent CEV is 0.42-0.52%, the Mn equivalent Sigma Mn is 1.20-1.35%, and the hardenability index J is more than or equal to 2.1; CEV=C+Mn/6+(Cr+Mo+V)/5+(Cu+Ni)/15; ∑Mn=Mn+3.28Mo+0.64Cr+0.5W+0.37Ni+0.23Cu+0.03Si+0.1(Alt+V+Ti+Nb); J=(1.24C-0.95C 2 )×(0.7Si+1)×(3.33Mn+1)×(2.16Cr+1)×(3Mo+1)×(0.36Ni+1)×(0.37Cu+1)×(1.73V+1)×(1.55Alt+1).
  4. 4. the method for producing steel sheet according to claim 1, wherein in the quenching step, water cooling is performed on a quenching machine, the ratio of water to water in the quenching machine is 0.75 to 0.85, and the running speed v of the steel sheet in the quenching machine is 34/a to (34/a+0.4) m/s.
  5. 5. The method for producing steel sheet according to claim 4, wherein in the quenching step, the quenching machine is started 20 to 30 seconds in advance before the steel sheet enters the quenching machine.
  6. 6. The method according to claim 1, wherein in the quenching step, the steel sheet passes through the high-pressure section and the low-pressure section successively, the water pressure in the high-pressure section is 0.79 to 0.81mpa, the water content is 6100 to 6400m 3 /h, the water pressure in the low-pressure section is 0.39 to 0.41mpa, and the water content is 5600 to 5900m 3 /h.
  7. 7. The method according to claim 1, wherein in the rolling step, the continuous casting billet is heated in a heating furnace at a soaking temperature of (T Nb(C,N) +30)℃~(T Nb(C,N) +60) °c for a soaking time of 0.1d to 0.5dmin and a total in-furnace time of 1.1d to 1.5dmin; wherein T Nb(C,N) =6770/(2.26) lg((C+12N/14)×Nb))-273。
  8. 8. The method according to claim 1, wherein in the rolling step, the continuous casting billet is heated and then subjected to rough rolling and finish rolling in this order to obtain the steel sheet, wherein the initial rolling temperature of rough rolling is (T Nb(C,N) -130)℃~(T Nb(C,N) -50) °c, the initial rolling temperature of finish rolling is (T nr -20)℃~(T nr +10) °c, and the final rolling temperature is (a r3 +60)℃~(A r3 +100) °c; wherein T Nb(C,N) =6770/(2.26) lg((C+12N/14)×Nb))-273; Recrystallization temperature T nr =887+464c+6445nb-644 +890Ti+363Alt-357Si; A r3 =910-310C-80Mn-20Cu-15Cr-55Ni-80Mo,A r3 is a temperature at which austenite precipitates ferrite during cooling.
  9. 9. The method according to claim 1, wherein the cooling rate in the cooling step is (V B +5) ℃/s~(V B +10) ° C/s.
  10. 10. A steel sheet, characterized in that the steel sheet is produced by the production method of the steel sheet according to any one of claims 1 to 9.
  11. 11. The steel plate according to claim 10, wherein the thickness a of the steel plate is 6-30 mm, the yield strength is not less than 1100MPa, the tensile strength is not less than 1400MPa, the hardness is not less than 420-460 HBW, the elongation is not less than 12%, the impact energy AKV is not less than 50J at-40 ℃, the bending center diameter D=3a is 180 degrees, the surface of the steel plate is free from cracks, the strength-plastic product of the steel plate is not less than 16.5GPa, and the residual stress is not more than 150MPa.
  12. 12. The steel sheet according to claim 10, wherein the steel sheet is welded without preheating when subjected to a cold crack welding test, and the surface, root and cross section of the steel sheet are crack-free; the steel plate is subjected to gas shielded flux-cored arc welding without preheating, and the welded joint has no delayed cracking.
  13. 13. The preheating-free welding method of the steel plate according to any one of claims 10 to 12, wherein the steel plate is subjected to gas shielded flux-cored arc welding without preheating, the ambient temperature is more than or equal to 15 ℃, 50 kg-grade and lower-grade low-hydrogen welding materials are selected for backing welding, the diffusion H content in the low-hydrogen welding materials is less than or equal to 5mL/100g, the welding current is less than or equal to 200A, the welding voltage is less than or equal to 26V, the welding line energy is less than or equal to 18kJ/cm, 80 kg-grade and lower-grade low-hydrogen welding materials are selected for filling and cover welding, the diffusion H content in the low-hydrogen welding materials is less than or equal to 5mL/100g, the welding current is less than or equal to 260A, the welding voltage is less than or equal to 31V, the welding line energy is less than or equal to 25kJ/cm, and the interlayer temperature is 200 to 250 ℃.

Description

Preheating-free welded steel plate and production method thereof, and preheating-free welding method Technical Field The application belongs to the technical field of steel alloy materials, relates to a steel plate capable of being welded without preheating and a production method thereof, and further relates to a steel plate welding method without preheating. Background Energy development and construction, especially exploitation of oil gas and mineral resources, cannot leave large engineering mechanical equipment. With the increase of energy demand, development areas have been expanded from common temperate regions to extremely low-temperature environments such as the north and south poles, high-altitude frozen soil zones and the like. Energy development operations are performed in these areas, and stringent requirements are placed on the performance of the construction machinery. Due to transportation constraints of large equipment and manufacturing requirements of complex structures, on-site splicing and assembly often do not avoid welding procedures. In the field working condition of extremely cold areas, the welding operation faces great challenges. In order to ensure the low-temperature toughness of the welded joint, complex pre-welding preheating and post-welding heat treatment processes are often required, which are difficult to implement under the field extremely cold condition, have huge energy consumption and are difficult to ensure the process stability. Disclosure of Invention The application aims to provide a steel plate capable of being welded without preheating, a production method thereof and a welding method without preheating. In order to achieve the above object, an embodiment of the present application provides a method for producing a steel sheet, including sequentially performing steps of blanking, rolling, cooling, quenching, and tempering; In the blank making process, preparing a continuous casting blank, and conveying the continuous casting blank into a heat preservation pit for heat preservation, wherein the temperature in the heat preservation pit is 630-670 ℃, and the heat preservation time t is more than or equal to D 2/40D in units of s, wherein D is the thickness of the continuous casting blank in units of mm, D is the hydrogen diffusion coefficient in the continuous casting blank in units of mm 2/s; in the rolling process, the continuous casting billet is heated and rolled into a steel plate; In the cooling step, the steel plate is cooled; In the quenching process, the cooled steel plate is sent into a heating furnace to be heated and then kept at the heating temperature of (A c3-30)℃~(Ac3 -10) DEG C, the furnace time is (1.5a+20) min to (1.5a+30) min, and then the steel plate is quickly cooled to room temperature, wherein the cooling speed is (V B+15) ℃/s~(VB +20) DEG C/s; in the tempering process, the steel plate after the quenching process is sent into a heating furnace to be heated and then kept at the heating temperature of (Ms-235) ° C to (Ms-210) ° C, and the furnace time is (5a+10) min to (5a+30) min; Wherein the austenitizing end temperature a c3 = 912-250C-16mn+48si-2Cr-16ni+95v+96ti+210alt-10Cu; The critical cooling speed V B=e(13.08-8.8C-1.07Mn-0.7Ni-0.57Cr-9.2Mo-366B)/3600 of bainite formation; Martensitic transformation start temperature ms=561-474C-33 Mn-17Cr-17Ni-21Mo; a is the thickness of the steel plate, and the unit is mm. In some embodiments, the chemical composition of the continuous casting billet comprises ：C 0.20~0.23%、Si 0.28~0.36%、Mn 0.90~1.10%、Cr 0.35~0.42%、Ti 0.012~0.019%、Alt 0.021~0.049%、B 0.0016~0.0021%、Zr 0.012~0.019%、Ca 0.0022~0.0052%、N 20~45ppm、O≤15ppm、H≤1.5ppm、P≤0.008%、S≤0.0012%, by mass percent of the balance Fe and unavoidable impurities. In some embodiments, the chemical components of the continuous casting blank are as follows, the carbon equivalent CEV is 0.42-0.52%, the Mn equivalent Sigma Mn is 1.20-1.35%, and the hardenability index J is more than or equal to 2.1; CEV=C+Mn/6+(Cr+Mo+V)/5+(Cu+Ni)/15; ∑Mn=Mn+3.28Mo+0.64Cr+0.5W+0.37Ni+0.23Cu+0.03Si+0.1(Alt+V+Ti+Nb); J=(1.24C-0.95C2)×(0.7Si+1)×(3.33Mn+1)×(2.16Cr+1)×(3Mo+1)×(0.36Ni+1)×(0.37Cu+1)×(1.73V+1)×(1.55Alt+1). In some embodiments, in the quenching process, water cooling is performed on a quenching machine, the water-to-water ratio of the quenching machine is 0.75-0.85, and the running speed v of the steel plate in the quenching machine is 34/a to (34/a+0.4) m/s. In some embodiments, in the quenching process, the quenching machine is started 20-30 seconds in advance before the steel plate enters the quenching machine. In some embodiments, in the quenching process, the steel plate passes through a high-pressure section and a low-pressure section in sequence during water cooling, the water pressure of the high-pressure section is 0.79-0.81 MPa, the water quantity is 6100-6400 m 3/h, the water pressure of the low-pressure section is 0.39-0.41 MPa, and the water quantity is 5600-5900