Simulated heat treatment process of super-thick Q345R end socket plate

Abstract

The invention discloses a simulated heat treatment process of an ultra-thick Q345R end socket plate, which comprises the following steps: (1) thermal forming: heating a steel plate to 900-930 DEG C, keeping the temperature for 1.5-2.0 min / mm, and air-cooling the steel plate after the steel plate is discharged from a furnace; (2) quenching is conducted, specifically, the steel plate is heated to 890-910 DEG C, the heat preservation time is 1.0-1.5 min / mm, and water cooling is conducted after the steel plate is discharged out of the furnace; (3) tempering is conducted, specifically, the steel plate is heated to 650-670 DEG C, the heat preservation time is 2.0-2.5 min / mm, and air cooling is conducted after the steel plate is discharged out of the furnace; and (4) post-weld heat treatment: charging the steel plate at the temperature of below 400 DEG C, heating to 600-630 DEG C at the speed of less than or equal to 55 DEG C / h, preserving heat for 10-12 hours, then cooling to 400 DEG C along with the furnace at the speed of less than or equal to 55 DEG C / h, and discharging and air cooling. The method can be used for guiding the setting of process parameters in the thermal forming process of the actual end socket by controlling the simulated heat treatment process, so that the ideal end socket performance is achieved, the simple manufacturing of the high-quality end socket is realized, and the mass production can be realized.

Description

Technical Field

[0001] The invention belongs to the technical field of steel production and relates to a simulated heat treatment process of an ultra-thick Q345R head plate. Background Art

[0002] With the extreme service environment of cryogenic pressure vessels and the high-end equipment, the market has more diverse and stringent requirements on the physical properties and chemical composition of Q345R low alloy steel for heads and cylinders, especially the thick Q345R head plates. The head is a component used to seal the end of the pressure vessel equipment to isolate the internal and external media. It is the main pressure-bearing component in the pressure vessel. During the manufacturing process of pressure vessel equipment, this component needs to undergo repeated stamping, high-temperature deformation, shear stress, welding and other processes, which have a great impact on the organization and mechanical properties. Therefore, the hot forming process and the recovery performance heat treatment process of the head plate during the processing are crucial. Summary of the invention

[0003] The purpose of the present invention is to provide a simulated heat treatment process for ultra-thick Q345R head plate, including hot forming, recovery performance quenching and tempering heat treatment and post-weld heat treatment. After heat treatment, the 130~150mm thick Q345R head plate has excellent mechanical properties, which can meet the mechanical properties of the steel plate core, namely, yield strength ReL≥330Mpa, tensile strength Rm=500~540Mpa, elongation A≥30%, and steel plate -20℃ low temperature impact KV2≥80J.

[0004] The technical solution of the present invention: A simulated heat treatment process for an ultra-thick Q345R head plate includes the following process steps: (1) Hot forming: Heat the steel plate to 900~930℃, keep it warm for 1.5~2.0 min / mm according to the thickness of the steel plate. Air cool the steel plate after it leaves the furnace. (2) Quenching: Heat the steel plate to 890~910℃, keep it warm for 1.0~1.5 min / mm (mm) according to the thickness of the steel plate, and water cool the steel plate after it leaves the furnace; (3) Tempering: Heat the steel plate to 650~670℃, keep it warm for 2.0~2.5 min / mm (mm / mm) according to the thickness of the steel plate, and air cool the steel plate after it leaves the furnace; (4) Post-weld heat treatment: The steel plate is loaded into the furnace at a temperature below 400°C, heated to 600-630°C at a rate of ≤55°C / h, kept at this temperature for 10-12h, then cooled to 400°C at a rate of ≤55°C / h, and air-cooled after being taken out of the furnace.

[0005] Furthermore, the chemical composition mass percentage of the steel plate applicable to the above heat treatment process is C=0.13%~0.16%, Si=0.25%~0.30%, Mn=1.40%~1.50%, P≤0.012%, S≤0.003%, Alt=0.020%~0.050%, Nb=0.015%~0.02%, V=0.025%~0.030%, Ni=0.20%~0.25%, Cu=0.20%~0.25%, and the others are Fe and essential residual elements.

[0006] After the simulated heat treatment process described above, the mechanical properties of the steel plate core are yield strength R eL ≥330Mpa, tensile strength R m =500~540Mpa, elongation A≥30%, low temperature impact of steel plate -20℃ KV2≥80J.

[0007] The beneficial effects of the present invention are as follows: by controlling the simulated heat treatment process, the performance of the ultra-thick Q345R head plate can be effectively guaranteed, and the simple manufacture of high-quality heads can be realized, and mass production can be realized. The simulated heat treatment process described in the present invention can meet the mechanical properties of the steel plate core: yield strength R eL ≥330Mpa, tensile strength R m =500~540Mpa, elongation A≥30%, low temperature impact of steel plate -20℃ KV2≥80J. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a 500-fold microstructure photograph of 1 / 2 the thickness of the steel plate produced in Example 1. DETAILED DESCRIPTION

[0009] The specific implementation manner of the present invention is described in detail below in conjunction with the embodiments, but the specific implementation manner of the present invention is not limited to the following embodiments. Example 1

[0010] The simulated heat treatment of Q345R steel plate has a thickness of 130 mm and its chemical composition by mass percentage is: C0.14%, Si0.26%, Mn1.42%, P0.011%, S0.003%, Alt0.036%, Nb0.017%, V0.026%, Ni0.23%, Cu0.21%, and the others are Fe and essential residual elements. The simulated heat treatment process is as follows: (1) Hot forming: Heat the steel plate to 900°C, keep it at this temperature for 210 minutes, and air cool it after it leaves the furnace; (2) Quenching: Heat the steel plate to 890°C, keep it at this temperature for 145 min, and water cool it after it leaves the furnace; (3) Tempering: Heat the steel plate to 670°C, keep it at this temperature for 270 min, and air cool the steel plate after it leaves the furnace; (4) Post-weld heat treatment: The steel plate is loaded into the furnace at a temperature below 400°C, heated to 620°C at a rate of 55°C / h, kept at this temperature for 11 hours, then cooled to 400°C at a rate of 55°C / h, and air-cooled after being taken out of the furnace.

[0011] The performance test results of the steel plate core after hot forming, quenching, tempering and post-weld heat treatment in this embodiment are as follows: yield strength R eL 335Mpa, tensile strength R m 522Mpa, elongation A 32%, steel plate -20℃ low temperature impact KV2187J, 167J, 175J. Example 2

[0012] The simulated heat treatment of Q345R steel plate has a thickness of 140 mm and its chemical composition by mass percentage is: C=0.15%, Si=0.28%, Mn=1.45%, P=0.010%, S=0.003%, Alt=0.039%, Nb=0.016%, V=0.028%, Ni=0.24%, Cu=0.23%, and the others are Fe and essential residual elements. The simulated heat treatment process is as follows: (1) Hot forming: Heat the steel plate to 920°C, keep it at this temperature for 230 minutes, and air cool it after it leaves the furnace; (2) Quenching: Heat the steel plate to 900°C, keep it at this temperature for 180 min, and water cool it after it comes out of the furnace; (3) Tempering: Heat the steel plate to 660°C, keep it at this temperature for 300 min, and air cool it after it leaves the furnace; (4) Post-weld heat treatment: The steel plate is loaded into the furnace at a temperature below 400°C, heated to 610°C at a rate of 55°C / h, kept at this temperature for 12 hours, then cooled to 400°C at a rate of 55°C / h, and air-cooled after being taken out of the furnace.

[0013] The performance test results of the steel plate core after hot forming, quenching, tempering and post-weld heat treatment in this embodiment are as follows: yield strength R eL 342Mpa, tensile strength R m 528Mpa, elongation A 33%, steel plate -20℃ low temperature impact KV2164J, 153J, 171J. Example 3

[0014] The simulated heat treatment of Q345R steel plate has a thickness of 150 mm and its chemical composition by mass percentage is: C=0.16%, Si=0.29%, Mn=1.48%, P=0.010%, S=0.002%, Alt=0.041%, Nb=0.017%, V=0.027%, Ni=0.23%, Cu=0.22%, and the others are Fe and essential residual elements. The simulated heat treatment process is as follows: (1) Hot forming: Heat the steel plate to 930°C, keep it at this temperature for 280 minutes, and air cool the steel plate after it leaves the furnace; (2) Quenching: Heat the steel plate to 910°C, keep it at this temperature for 190 min, and water cool it after it leaves the furnace; (3) Tempering: Heat the steel plate to 650°C, keep it at this temperature for 320 min, and air cool it after it leaves the furnace; (4) Post-weld heat treatment: The steel plate is loaded into the furnace at a temperature below 400°C, heated to 630°C at a rate of 55°C / h, kept at this temperature for 10 hours, then cooled to 400°C at a rate of 55°C / h, and air-cooled after being taken out of the furnace.

[0015] The performance test results of the steel plate core after hot forming, quenching, tempering and post-weld heat treatment in this embodiment are as follows: yield strength R eL 340Mpa, tensile strength R m 533Mpa, elongation A 32%, steel plate -20℃ low temperature impact KV2176J, 193J, 188J.

Claims

1. A simulated heat treatment process for ultra-thick Q345R head plate, characterized in that: The process steps include: (1) Hot forming: Heat the steel plate to 900~930℃, keep it warm for 1.5~2.0 min / mm according to the thickness of the steel plate. Air cool the steel plate after it leaves the furnace. (2) Quenching: Heat the steel plate to 890~910℃, keep it warm for 1.0~1.5 min / mm (mm) according to the thickness of the steel plate, and water cool the steel plate after it leaves the furnace; (3) Tempering: Heat the steel plate to 650~670℃, keep it warm for 2.0~2.5 min / mm (mm / mm) according to the thickness of the steel plate, and air cool the steel plate after it leaves the furnace; (4) Post-weld heat treatment: The steel plate is loaded into the furnace at a temperature below 400°C, heated to 600-630°C at a rate of ≤55°C / h, kept at this temperature for 10-12h, then cooled to 400°C at a rate of ≤55°C / h, and air-cooled after being taken out of the furnace.

2. The simulated heat treatment process for hot forming of ultra-thick Q345R head plate according to claim 1 is characterized in that: The chemical composition mass percentage of the applicable steel plate is C=0.13%~0.16%, Si=0.25%~0.30%, Mn=1.40%~1.50%, P≤0.012%, S≤0.003%, Alt=0.020%~0.050%, Nb=0.015%~0.02%, V=0.025%~0.030%, Ni=0.20%~0.25%, Cu=0.20%~0.25%, and the others are Fe and essential residual elements.

3. The simulated heat treatment process of the ultra-thick Q345R head plate according to claim 1 is characterized in that: After the simulated heat treatment process, the mechanical properties of the steel plate core are yield strength R eL ≥330Mpa, tensile strength R m =500~540Mpa, elongation A≥30%, low temperature impact of steel plate -20℃ KV2≥80J.

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