A Q690D steel plate with high and low temperature impact toughness and its production method

Abstract

The present invention provides a Q690D steel plate with high and low temperature impact toughness and a production method thereof. The Q690D steel plate with high and low temperature impact toughness is designed with low-C steel, and Nb, V, and Ti elements are added to improve the strength of the steel plate; Cr and Mo elements improve hardenability, and P, S, N, and impurity elements are strictly controlled. The production method of the Q690D steel plate with high and low temperature impact toughness includes the following technological steps: hot metal pretreatment, converter steelmaking, post-furnace argon blowing, LF steel refining treatment, RH steel refining treatment, slab continuous casting, slab heating, descaling, rough rolling, finish rolling, preliminary straightening, ultra-fast cooling process, straightening, cooling bed, tempering, sampling, steel plate inspection, marking and warehousing. The Q690D steel plate produced by the present invention has high strength, excellent comprehensive properties such as plasticity, toughness, bending, and welding, and meets the use requirements of users.

Description

Technical Field

[0001] The present invention relates to the field of steel production and manufacturing, and particularly relates to a Q690D steel plate and a production method thereof, especially a Q690D steel plate with high and low temperature impact toughness and a production method thereof. Background Art

[0002] Q690D high-strength steel is a grade in the national standard GB / T 1591-2008 "Low-alloy High-strength Structural Steel", which requires a yield strength ReL≥690 MPa, a tensile strength Rm of 770-940 MPa, an elongation A≥14%, a -20°C low-temperature impact ≥47 J, and a qualified 180° cold bending performance. It is applied in mining machinery, port machinery, cranes, iron anchors, shield machines, hydraulic supports, tower cranes, and various steel structures. Engineering construction machinery such as excavators and loaders often work in complex environments and often need to bear large impact loads during operation. And with the continuous development of engineering construction machinery manufacturers towards high strength and lightweight, the requirement for the low-temperature impact toughness of steel plate materials is getting higher and higher. While ensuring high strength, it has always been a major difficulty to ensure excellent comprehensive properties such as plasticity, toughness, bending, and welding.

[0003] In summary, the following problems exist in the prior art: how to ensure the low-temperature impact toughness of the Q690D steel plate while ensuring its high strength to meet the user's usage requirements. Summary of the Invention

[0004] The present invention provides a Q690D steel plate and a production method thereof, especially a Q690D steel plate with high and low temperature impact toughness and a production method thereof, to solve the problem of ensuring the low-temperature impact toughness of the Q690D steel plate while ensuring its high strength to meet the user's usage requirements.

[0005] For this purpose, the present invention proposes a production method of a Q690D steel plate with high and low temperature impact toughness. The chemical composition weight percentage of the Q690D steel plate with high and low temperature impact toughness is as follows: C: 0.05-0.10 wt%, Si: 0.40-0.60 wt%, Mn: 1.70-1.90 wt%, P≤0.020 wt%, S≤0.008 wt%, Nb: 0.02-0.10 wt%, V: 0.02-0.10 wt%, Ti: 0.03-0.08 wt%, Cr: 0.10-0.50 wt%, Mo: 0.30-0.50 wt%, Alt: 0.02-0.03 wt%, N≤0.006 wt%;

[0006] The production method of the Q690D steel plate with high and low temperature impact toughness includes the following technological steps carried out in sequence:

[0007] Hot metal pretreatment, converter steelmaking, post-furnace argon blowing, LF steel refining treatment, RH steel refining treatment, slab continuous casting, slab heating, descaling, rough rolling, finish rolling, pre-straightening, ultra-fast cooling process, straightening, cooling bed, tempering, sampling, steel plate inspection, marking and warehousing;

[0008] Among them, the rough rolling starting temperature is 1000 - 1140 °C; the finish rolling starting temperature is 940 - 1000 °C, and the finish rolling ending temperature is 850 - 890 °C.

[0009] Furthermore, the ultra-fast cooling process includes that after the finish rolling of the steel plate, it enters the ultra-fast cooling zone, ensuring that the starting temperature of ultra-fast cooling of the steel plate is ≥ 750 °C, the ultra-fast cooling water pressure is ≥ 0.3 MPa, the cooling rate is 20 - 35 °C / s, and the reheat temperature after cooling is ≤ 230 °C.

[0010] Furthermore, for the tempering: the tempering temperature is 570 ± 10 °C, and the tempering time is the plate thickness + 50 min.

[0011] Furthermore, for the converter steelmaking: desulfurization of hot metal is carried out to ensure that the S content of the hot metal entering the furnace is ≤ 0.010%, and class I scrap is used; the whole process adopts bottom blowing argon gas, and the end-point control of the converter is C ≤ 0.06 wt%, P ≤ 0.015 wt%.

[0012] Furthermore, for the LF steel refining treatment: desulfurization, temperature balancing, alloying treatment and inclusion removal of the molten steel are carried out in the LF furnace; after the last alloying, it is necessary to ensure a medium-intensity or strong argon blowing time of 3 - 20 min; soft argon blowing is carried out for 8 - 10 min before the end of refining.

[0013] Furthermore, for the RH steel refining treatment: the total vacuum circulation time is 15 - 20 min, the ultimate vacuum holding time is more than 10 min, the net circulation time is more than 3 min, and the soft argon blowing time after calcium treatment is 8 - 10 min.

[0014] Furthermore, for the slab continuous casting, the tundish pouring temperature is 1524 - 1543 °C, a low-alloy steel mold powder is used, the casting speed of the slab is 0.80 - 1.42 m / min, and the electromagnetic stirring process is used.

[0015] Furthermore, for the slab heating: the soaking section temperature is above 1200 °C, ensuring that the heating time is ≥ 230 min.

[0016] The present invention also provides a Q690D steel plate with high and low temperature impact toughness, which is made by the method of any one of the foregoing steps. The chemical composition of the Q690D steel plate with high and low temperature impact toughness is as follows by weight percentage: C: 0.05 - 0.10 wt%, Si: 0.40 - 0.60 wt%, Mn: 1.70 - 1.90 wt%, P ≤ 0.020 wt%, S ≤ 0.008 wt%, Nb: 0.02 - 0.10 wt%, V: 0.02 - 0.10 wt%, Ti: 0.03 - 0.08 wt%, Cr: 0.10 - 0.50 wt%, Mo: 0.30 - 0.50 wt%, Alt: 0.02 - 0.03 wt%, N ≤ 0.006 wt%.

[0017] Furthermore, the thickness of the Q690D steel plate with high and low temperature impact toughness is 6 - 50 mm.

[0018] Furthermore, the chemical composition of the Q690D steel plate (6 mm specification) with high and low temperature impact toughness is as follows by weight percentage: C: 0.06 wt%, Si: 0.45 wt%, Mn: 1.72 wt%, P: 0.015 wt%, S: 0.006 wt%, Nb: 0.034 wt%, V: 0.041 wt%, Ti: 0.032 wt%, Cr: 0.18 wt%, Mo: 0.36 wt%, Alt: 0.028 wt%, N: 0.005 wt%; the rough rolling starting temperature is 1070 °C; the finish rolling starting temperature is 990 °C, the finish rolling final temperature is 880 °C. The ultra-fast cooling process ensures that the ultra-fast cooling starting temperature of the steel plate is 765 °C, the ultra-fast cooling water pressure is 0.32 MPa, the cooling rate is 32 °C / s, and the post-cooling red return temperature is 158 °C; the tempering temperature is 575 °C, and the tempering time is 56 min.

[0019] Furthermore, the chemical composition of the Q690D steel plate (20 mm specification) with high and low temperature impact toughness is as follows by weight percentage: C: 0.07 wt%, Si: 0.47 wt%, Mn: 1.77 wt%, P: 0.014 wt%, S: 0.006 wt%, Nb: 0.042 wt%, V: 0.045 wt%, Ti: 0.033 wt%, Cr: 0.20 wt%, Mo: 0.37 wt%, Alt: 0.027 wt%, N: 0.005 wt%; the rough rolling starting temperature is 1066 °C; the finish rolling starting temperature is 982 °C, the finish rolling final temperature is 872 °C. The ultra-fast cooling process ensures that the ultra-fast cooling starting temperature of the steel plate is 756 °C, the ultra-fast cooling water pressure is 0.42 MPa, the cooling rate is 29 °C / s, and the post-cooling red return temperature is 170 °C; the tempering temperature is 572 °C, and the tempering time is 70 min.

[0020] Furthermore, the chemical composition of the Q690D steel plate with high and low temperature impact toughness (30 mm specification) in weight percentage is as follows: C: 0.07 wt%, Si: 0.42 wt%, Mn: 1.76 wt%, P: 0.012 wt%, S: 0.006 wt%, Nb: 0.052 wt%, V: 0.066 wt%, Ti: 0.034 wt%, Cr: 0.20 wt%, Mo: 0.37 wt%, Alt: 0.026 wt%, N: 0.005 wt%; the rough rolling starting temperature is 1053 °C; the finish rolling starting temperature is 975 °C, and the finish rolling ending temperature is 865 °C. The ultra-fast cooling process ensures that the ultra-fast cooling starting temperature of the steel plate is 776 °C, the ultra-fast cooling water pressure is 0.45 MPa, the cooling rate is 28 °C / s, and the temperature after cooling and returning to red is 162 °C; the tempering temperature is 576 °C, and the tempering time is 80 min.

[0021] Furthermore, the chemical composition of the Q690D steel plate with high and low temperature impact toughness (40 mm specification) in weight percentage is as follows: C: 0.09 wt%, Si: 0.41 wt%, Mn: 1.80 wt%, P: 0.013 wt%, S: 0.005 wt%, Nb: 0.062 wt%, V: 0.043 wt%, Ti: 0.033 wt%, Cr: 0.22 wt%, Mo: 0.38 wt%, Alt: 0.028 wt%, N: 0.005 wt%; the rough rolling starting temperature is 1042 °C; the finish rolling starting temperature is 970 °C, and the finish rolling ending temperature is 872 °C. The ultra-fast cooling process ensures that the ultra-fast cooling starting temperature of the steel plate is 780 °C, the ultra-fast cooling water pressure is 0.48 MPa, the cooling rate is 28 °C / s, and the temperature after cooling and returning to red is 201 °C; the tempering temperature is 571 °C, and the tempering time is 90 min.

[0022] Furthermore, the chemical composition of the Q690D steel plate with high and low temperature impact toughness (50 mm specification) in weight percentage is as follows: C: 0.10 wt%, Si: 0.52 wt%, Mn: 1.88 wt%, P: 0.014 wt%, S: 0.006 wt%, Nb: 0.070 wt%, V: 0.052 wt%, Ti: 0.035 wt%, Cr: 0.30 wt%, Mo: 0.40 wt%, Alt: 0.030 wt%, N: 0.005 wt%; the rough rolling starting temperature is 1050 °C; the finish rolling starting temperature is 956 °C, and the finish rolling ending temperature is 860 °C. The ultra-fast cooling process ensures that the ultra-fast cooling starting temperature of the steel plate is 762 °C, the ultra-fast cooling water pressure is 0.50 MPa, the cooling rate is 25 °C / s, and the temperature after cooling and returning to red is 215 °C; the tempering temperature is 576 °C, and the tempering time is 100 min.

[0023] In the present invention, a Q690D steel plate with high and low temperature impact toughness is designed using low-carbon steel, and elements such as Nb, V, and Ti are added to increase the strength of the steel plate. Elements such as Cr and Mo improve hardenability, and P, S, N, and impurity elements are strictly controlled. The chemical composition of the Q690D steel plate with high and low temperature impact toughness is as follows in weight percentage: C: 0.05 - 0.10wt%, Si: 0.40 - 0.60wt%, Mn: 1.70 - 1.90wt%, P ≤ 0.020wt%, S ≤ 0.008wt%, Nb: 0.02 - 0.10wt%, V: 0.02 - 0.10wt%, Ti: 0.03 - 0.08wt%, Cr: 0.10 - 0.50wt%, Mo: 0.30 - 0.50wt%, Alt: 0.02 - 0.03wt%, N ≤ 0.006wt%. In the process steps based on the above reasonable composition design, the rough rolling starting temperature is 1000 - 1140°C; the finish rolling starting temperature is 940 - 1000°C, and the finish rolling ending temperature is 850 - 890°C. The Q690D steel plate produced by the present invention through the above process, while ensuring its high strength and light weight, can also ensure its excellent comprehensive properties such as plasticity, toughness, bending, and welding. The yield strength ReL is 730 - 763MPa, the tensile strength Rm is 820 - 885MPa, the elongation A is 15 - 20%, the 180° cold bending performance is qualified, the comprehensive performance is excellent, there is sufficient margin, and the low-temperature impact at -20°C is stable at 202 - 285J, ensuring its low-temperature impact toughness and well meeting the user's usage requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a -20°C impact fracture photo of the sample of Example 5 of the Q690D steel plate with high and low temperature impact toughness of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] In order to have a clearer understanding of the technical features, objectives, and effects of the present invention, the present invention is now described.

[0026] The objective of the present invention is to provide a Q690D steel plate with high and low temperature impact toughness and its production method through specific composition design, reasonable rolling parameters, ultra-fast cooling process, and heat treatment tempering process.

[0027] I. To achieve the above objective, the technical solution adopted by the present invention is as follows:

[0028] In the present invention, the Q690D steel plate with high and low temperature impact toughness is designed with low-carbon steel, and Nb, V, and Ti elements are added to improve the strength of the steel plate, while Cr and Mo elements improve hardenability. P, S, N, and impurity elements are strictly controlled. The chemical composition of the Q690D steel plate with high and low temperature impact toughness in weight percentage is as follows: C: 0.05 - 0.10 wt%, Si: 0.40 - 0.60 wt%, Mn: 1.70 - 1.90 wt%, P ≤ 0.020 wt%, S ≤ 0.008 wt%, Nb: 0.02 - 0.10 wt%, V: 0.02 - 0.10 wt%, Ti: 0.03 - 0.08 wt%, Cr: 0.10 - 0.50 wt%, Mo: 0.30 - 0.50 wt%, Alt: 0.02 - 0.03 wt%, N ≤ 0.006 wt%.

[0029] The production process route of the Q690D steel plate with high and low temperature impact toughness is as follows: hot metal pretreatment → converter steelmaking → post-furnace argon blowing → LF steel refining (ladle refining) treatment → RH steel refining (molten steel vacuum circulation degassing method steel refining) treatment → slab continuous casting → slab heating → descaling → rough rolling → finish rolling → pre-straightening → ultra-fast cooling process (UFC ultra-fast cooling) → straightening → cooling bed → tempering → sampling → steel plate inspection → marking and warehousing. Among them, the process characteristics of each stage are as follows:

[0030] (1) Converter steelmaking: Desulfurize the hot metal to ensure that the S content of the hot metal entering the furnace is ≤ 0.010%, use grade I scrap steel to reduce the external input of harmful impurity elements; the whole process uses bottom blowing argon gas, and the converter end point controls C ≤ 0.06 wt% and P ≤ 0.015 wt%.

[0031] (2) LF steel refining treatment: Desulfurize, balance the temperature, alloyize, and remove inclusions from the molten steel in the LF furnace; after the last alloying, it is necessary to ensure a medium-strength or strong argon blowing time of 3 - 20 minutes; soft argon blowing for 8 - 10 minutes before the end of refining.

[0032] (3) RH steel refining treatment: The total vacuum circulation time is 15 - 20 minutes, the ultimate vacuum holding time is more than 10 minutes, the net circulation time is more than 3 minutes, and the soft argon blowing time after calcium treatment is 8 - 10 minutes.

[0033] (4) Slab continuous casting: The tundish pouring temperature is 1524 - 1543 °C, use low-alloy steel mold powder, the casting speed of the slab is 0.80 - 1.42 m / min, and use electromagnetic stirring technology to reduce the center segregation of the slab and improve the internal quality of the slab.

[0034] (5) Slab heating: The content of microalloying element Nb is high. To ensure the full solution of the second phase of Nb in the steel so that it can precipitate sufficiently during the subsequent controlled rolling and controlled cooling processes to better play the strengthening role, it is necessary to control the heating temperature, especially the soaking section temperature above 1200 °C, and ensure the heating time ≥ 230 min. The slab thickness is 220 mm, the width is 1810 mm, the finished product thickness is 6 - 50 mm, and the width is 2000 - 2600 mm.

[0035] (6) Rolling process: The rough rolling starting temperature is 1000 - 1140 °C, the finish rolling starting temperature is 940 - 1000 °C, and the finish rolling ending temperature is 850 - 890 °C; High-pressure water descaling is used to reduce defects such as the pressing-in of surface scale and pitting, and ensure the surface quality of the steel plate.

[0036] (7) Ultra-fast cooling process: To avoid the precipitation of a large amount of proeutectoid massive ferrite after finish rolling and before the start of cooling, which weakens the effect of tissue strengthening, it is necessary to enter the ultra-fast cooling zone as soon as possible after finish rolling. Ensure that the ultra-fast cooling starting temperature of the steel plate ≥ 750 °C, the ultra-fast cooling water pressure ≥ 0.3 MPa, the cooling rate is 20 - 35 °C / s, and the return red temperature after cooling ≤ 230 °C.

[0037] (8) Tempering: The steel plate is subjected to tempering heat treatment. To ensure the uniformity of the structure and properties, the tempering temperature is 570 ± 10 °C, and the tempering time is the plate thickness + 50 min.

[0038] II. Embodiment

[0039] (1) The Q690D steel plate with high and low temperature impact toughness and its production method of the present invention adopt the following component ratios. Table 1 shows the chemical compositions of the products of each embodiment (by weight percentage).

[0040] Table 1: Chemical compositions of products (wt%)

[0041] Example C Si Mn P S Nb V Ti Cr Mo Alt N Example 1 0.06 0.45 1.72 0.015 0.006 0.034 0.041 0.032 0.18 0.36 0.028 0.005 Example 2 0.06 0.45 1.72 0.015 0.006 0.034 0.041 0.032 0.18 0.36 0.028 0.005 Example 3 0.07 0.47 1.77 0.014 0.006 0.042 0.045 0.033 0.20 0.37 0.027 0.005 Example 4 0.07 0.47 1.77 0.014 0.006 0.042 0.045 0.033 0.20 0.37 0.027 0.005 Example 5 0.07 0.42 1.76 0.012 0.006 0.052 0.066 0.034 0.20 0.37 0.026 0.005 Example 6 0.07 0.42 1.76 0.012 0.006 0.052 0.066 0.034 0.20 0.37 0.026 0.005 Example 7 0.09 0.41 1.80 0.013 0.005 0.062 0.043 0.033 0.22 0.38 0.028 0.005 Example 8 0.09 0.41 1.80 0.013 0.005 0.062 0.043 0.033 0.22 0.38 0.028 0.005 Example 9 0.10 0.52 1.88 0.014 0.006 0.070 0.052 0.035 0.30 0.40 0.030 0.005 Example 10 0.10 0.52 1.88 0.014 0.006 0.070 0.052 0.035 0.30 0.40 0.030 0.005

[0042] (2) To produce a Q690D steel plate with high and low temperature impact toughness in the thickness specification of 6 - 50 mm, the following specific process is adopted. The corresponding process parameters of the products of each embodiment are shown in Table 2.

[0043] Table 2: Specific process parameters of each embodiment

[0044]

[0045] (3) The Q690D steel plate produced according to the above process technology has a yield strength ReL of 730 - 763 MPa, a tensile strength Rm of 820 - 885 MPa, an elongation A of 15 - 20%, qualified 180° cold bending performance, excellent comprehensive performance, sufficient margin, and the -20°C low-temperature impact is stable at 202 - 285 J. The detailed mechanical properties are shown in Table 3.

[0046] Table 3: Mechanical properties of the products of each example

[0047]

[0048]

[0049] (4) The metallographic structures of the above example products are all mixed structures of lath bainite and a small amount of acicular ferrite. The laths are fine and cross each other. The structure is uniform throughout the thickness section, and there are no obvious segregation, microcracks, and delamination phenomena at the center; various inclusions are ≤ grade 1.0, and the steel quality is pure.

[0050] (5) Figure 1 Figure 16 is a -20°C impact fracture surface photo of the sample of Example 5 with a thickness specification of 30 mm. The fracture surface is dark gray fibrous and dull, which is the macroscopic morphology of a typical ductile fracture. Obvious and relatively deep dimple features can be observed under the scanning electron microscope. The average impact energy is 250 J, and the low-temperature impact toughness performance is excellent. (Remarks: The standard impact specimen thickness is 10 mm, and the thickness of the 6 mm specification impact sample can only be 5 mm, and the corresponding required value only needs to be half of the standard sample).

[0051] The present invention provides a Q690D steel plate with high and low-temperature impact toughness and its production method. The steel plate produced by this process technology has good uniformity of metallographic structure and mechanical properties at different positions of the whole plate. The yield strength ReL is 730 - 763 MPa, the tensile strength Rm is 820 - 885 MPa, the elongation A is 15 - 20%, the 180° cold bending performance is qualified, the comprehensive performance is excellent, and the margin is sufficient. It meets the requirements of the grade Q690D in the national standard GB / T 1591-2008 "Low-alloy high-strength structural steel" and the usage requirements in engineering machinery. Moreover, the -20°C low-temperature impact is stable at 202 - 285 J, far exceeding the standard -20°C impact ≥ 47 J, and well meeting the usage needs of users.

[0052] The above are only the schematic specific embodiments of the present invention and are not intended to limit the scope of the present invention. The various components of the present invention can be combined with each other under the condition of no conflict. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A production method of Q690D steel plate with high and low temperature impact toughness, characterized in that, The chemical composition of the Q690D steel plate with high and low temperature impact toughness is as follows by weight percentage: C: 0.09 - 0.10 wt%, Si: 0.41 - 0.52 wt%, Mn: 1.80 - 1.88 wt%, P ≤ 0.020 wt%, S ≤ 0.008 wt%, Nb: 0.062 - 0.070 wt%, V: 0.043 - 0.052 wt%, Ti: 0.033 - 0.035 wt%, Cr: 0.22 - 0.30 wt%, Mo: 0.38 - 0.40 wt%, Alt: 0.028 - 0.03 wt%, N ≤ 0.006 wt%. The production method of the Q690D steel plate with high and low temperature impact toughness includes the following technological steps carried out in sequence: Hot metal pretreatment, converter steelmaking, post-furnace argon blowing, LF steel refining treatment, RH steel refining treatment, slab continuous casting, slab heating, descaling, rough rolling, finish rolling, pre-straightening, ultra-fast cooling process, straightening, cooling bed, tempering, sampling, steel plate inspection, marking and warehousing; Among them, the rough rolling starting temperature is 1000 - 1140 °C; the finish rolling starting temperature is 940 - 1000 °C, and the finish rolling ending temperature is 850 - 890 °C; The ultra-fast cooling process includes that after the finish rolling of the steel plate, it enters the ultra-fast cooling zone, ensuring that the starting temperature of ultra-fast cooling of the steel plate ≥ 750 °C, the ultra-fast cooling water pressure ≥ 0.3 MPa, the cooling rate is 20 - 35 °C / s, and the return red temperature after cooling ≤ 230 °C; The tempering: the tempering temperature is 570 ± 10 °C, and the tempering time is the plate thickness + 50 min; The thickness of the Q690D steel plate with high and low temperature impact toughness is 40 - 50 mm; The yield strength ReL of the steel plate is 733 - 741 MPa, the tensile strength Rm is 834 - 872 MPa, the elongation A is 16.5 - 18%, the 180° cold bending performance is qualified, the comprehensive performance is excellent, and there is sufficient margin, meeting the requirements of the grade Q690D in the national standard GB / T 1591 - 2008 "Low-alloy high-strength structural steel" and the usage requirements in engineering machinery, and the low-temperature impact at -20 °C is stable at 220 - 266 J, far exceeding the standard -20 °C impact ≥ 47 J.

2. The production method of Q690D steel plate with high and low temperature impact toughness as described in claim 1, characterized in that, The converter steelmaking: desulfurize the hot metal to ensure that the S in the hot metal entering the furnace ≤ 0.010%, and use type I scrap steel; the whole process uses bottom blowing argon gas, and the converter end point controls C ≤ 0.06 wt%, P ≤ 0.015 wt%.

3. The production method of a Q690D steel plate with high and low temperature impact toughness as described in claim 1, characterized in that, The LF steel refining treatment: desulfurize, balance the temperature, alloying treatment and remove inclusions of the molten steel in the LF furnace; it is necessary to ensure a medium-strength argon blowing or strong argon blowing time of 3 - 20 min after the last alloying; soft argon blowing for 8 - 10 min before the end of refining.

4. A production method of Q690D steel plate with high and low temperature impact toughness as described in claim 1, characterized in that, The RH steel refining treatment: the total vacuum circulation time is 15 - 20 min, the ultimate vacuum holding time is more than 10 min, the net circulation time is more than 3 min, and the soft argon blowing time after calcium treatment is 8 - 10 min.

5. The production method of a Q690D steel plate with high and low temperature impact toughness as described in claim 1, characterized in that, The slab continuous casting: the tundish pouring temperature is 1524 - 1543 °C, a low-alloy steel mold powder is used, the casting speed of the slab is 0.80 - 1.42 m / min, and an electromagnetic stirring process is used.

6. The production method of a Q690D steel plate with high and low temperature impact toughness according to claim 1, characterized in that, The slab heating: the soaking section temperature is above 1200 °C, and the heating time is guaranteed to be ≥ 230 min.

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