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New steel plate with higher impact toughness than P690QL2 steel plate for LPG ship storage tanks and production method thereof

A technology of impact toughness and steel plates, which is applied in the field of steel plate production for marine storage tanks. It can solve the problems of insufficient safety factor and low low-temperature impact toughness, and achieve the effects of reasonable composition design, improved low-temperature impact toughness, and improved strength and toughness.

Active Publication Date: 2020-09-04
NANYANG HANYE SPECIAL STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But the low-temperature impact toughness of the standard P690QL2 is still relatively low, and the safety factor is not high enough

Method used

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  • New steel plate with higher impact toughness than P690QL2 steel plate for LPG ship storage tanks and production method thereof
  • New steel plate with higher impact toughness than P690QL2 steel plate for LPG ship storage tanks and production method thereof
  • New steel plate with higher impact toughness than P690QL2 steel plate for LPG ship storage tanks and production method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0045] This embodiment provides a new type of steel plate with higher impact toughness than the P690QL2 steel plate for LPG ship storage tanks, including the following chemical components in mass percentages: C 0.07, Si 0.15, Mn 1.10, P 0.007, S 0.003, Als 0.035, Nb 0.035, V0.035, Ni 1.2, Cr 0.35, Mo 0.30 and B 0.0009, the balance is Fe and residual elements;

[0046] The welding crack sensitivity index of the P690QL2 steel plate of Example 1: Pcm=C+Si / 30+Mn / 20+Cu / 20+Ni / 60+Cr / 20+Mo / 15+V / 10+5B=0.195<0.26 %.

[0047] The reheat crack sensitivity index of the above P690QL2 steel plate: PSR=Cr+Cu+2Mo+10V+7Nb+5Ti-2=-0.455<0.

[0048] The thickness of the above P690QL2 original steel ingot is 550mm, the thickness of the finished product is 16mm, the compression ratio is 550 / 16=34>6,

[0049] Its production methods include:

[0050] For the KR pretreatment of the molten iron, remove the slag before and after the molten iron arrives at the station. The thickness of the slag layer o...

Embodiment 2

[0059] This embodiment provides a new type of steel plate with higher impact toughness than the P690QL2 steel plate for LPG ship storage tanks, including the following chemical components in mass percentages: C 0.07, Si 0.15, Mn 1.15, P 0.008, S 0.002, Als 0.033, Nb 0.038, V0.040, Ni 1.30, Cr 0.40, Mo 0.40 and B 0.0008, the balance is Fe and residual elements;

[0060] The welding crack sensitivity index of the P690QL2 steel plate of Example 2: Pcm=0.209<0.26%.

[0061] Reheat crack sensitivity index: PSR=Cr+Cu+2Mo+10V+7Nb+5Ti-2=-0.184<0.

[0062] The P690QL2 original steel ingot thickness of embodiment 2 is 680mm, the finished product thickness is 50mm, compression ratio 680 / 50=13.6>6:

[0063] The difference between the production method of the P690QL2 steel plate and that in Example 1 is: the molten iron is pretreated with KR, the sulfur cycle is 25 minutes, and the desulfurization temperature drop is 20°C. After refining and heating, 1350Kg of lime and 130Kg of fluorite ...

Embodiment 3

[0065] This embodiment provides a new type of steel plate with higher impact toughness than the P690QL2 steel plate for LPG ship storage tanks, including the following chemical components in mass percentages: C 0.08, Si 0.13, Mn 1.23, P 0.006, S 0.002, Als 0.032, Nb 0.040, V0.050, Ni 1.40, Cr 0.35, Mo 0.40 and B 0.0010, the balance is Fe and residual elements;

[0066] The welding crack sensitivity index of the P690QL2 steel plate of Example 3: Pcm=0.223<0.26%.

[0067] Reheat crack sensitivity index: PSR=Cr+Cu+2Mo+10V+7Nb+5Ti-2=-0.07<0.

[0068] The thickness of the P690QL2 original steel ingot in Example 3 is 720mm, the thickness of the finished product is 80mm, and the compression ratio is 720 / 80=9>6:

[0069]The difference between the production method of this P690QL2 steel plate and that in Examples 1 and 2 is that in the rolling process, the thickness of the billet is 350mm, the thickness of the rough rolling cold steel is 130mm, the finish rolling is 760°C, the final r...

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Abstract

The invention discloses a new steel plate with higher impact toughness than a P690QL2 steel plate for LPG ship storage tanks and a production method thereof. The new steel plate comprises the following mass percentages of chemical compositions: 0.07-0.12 of C, 0.10-0.20 of Si, 1.00-1.60 of Mn, P less than or equal to 0.010, S less than or equal to 0.003, 0.020-0.050 of Als, 0.030-0.060 of Nb, 0.030-0.070 of V, 0.30-1.50 of Ni, 0.30-0.50 of Cr, 0.20-0.50 of Mo, 0.0008-0.0015 of B, and the balance of Fe and residual elements, wherein the new steel plate has more than 80% of a tempered bainite and less than 20% of a tempered sorbite structure, and the transverse impact value of -60 DEG C is greater than or equal to 120J; and the new steel plate is obtained by production processes including ingot heating, cogging rolling and segmentation, billet heating, controlled rolling and cooling, and heat treatment. Compared with the prior art, through the reasonable design of the steel plate compositions and production method, the new steel plate provided by the invention obtains a reasonable combination of steel plate matrix structure, has high strength, excellent low-temperature impact toughness and good welding performance, and can meet the requirements of industrial manufacturing of large-scale LPG ship storage tanks.

Description

technical field [0001] The invention belongs to the field of manufacturing steel plates for marine storage tanks, in particular to a novel steel plate with higher impact toughness than P690QL2 steel plates for LPG ship storage tanks and a production method thereof. Background technique [0002] At present, more than 30% of the world's liquefied petroleum gas (LPG: Liquefied Petroleum Gas) is mainly shipped by sea. The main components of LPG are propane and butane, its liquefaction temperature is below -40°C, and its expansion coefficient is high. The vaporization volume of 1L of LPG can reach 250L. [0003] In order to ensure greater carrying capacity, LPG marine storage tanks are developing in the direction of large-scale and high-strength, and at the same time, the requirements for low-temperature toughness and weldability of steel plates for storage tanks are increasing. For example, a 5500m3 full-pressure LPG ship is composed of two storage tanks. The nominal volume of ...

Claims

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Application Information

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IPC IPC(8): C22C38/02C22C38/04C22C38/06C22C38/48C22C38/46C22C38/44C22C38/54C21D8/02
CPCC21D8/0205C21D8/0226C21D8/0247C21D2211/002C22C38/02C22C38/04C22C38/06C22C38/44C22C38/46C22C38/48C22C38/54
Inventor 朱书成郑海明许少普李忠波张涛唐郑磊杨阳刘庆波杨东张占杰李亮康文举于飒王英杰符可义薛艳生袁继恒庞百鸣屈晓彬朱先兴袁高俭王希彬任义白艺波杨春
Owner NANYANG HANYE SPECIAL STEEL CO LTD
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