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Steel HG785D for tower crane and production method

A technology of tower cranes and production methods, which is applied to the improvement of process efficiency, etc., and can solve the problems of increased thickness of extra-thick steel plates, inability to guarantee the strength and toughness of extra-thick steel plates and uniformity of thickness direction performance, and reduced cooling speed.

Active Publication Date: 2013-12-25
NANYANG HANYE SPECIAL STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In general, the maximum thickness of HG785D extra-thick steel and its similar products is mostly 150mm. When producing HG785D extra-thick steel larger than 150mm, the main issues that need to be considered: ①The thickness of the extra-thick plate increases, and the cooling rate decreases greatly. Toughness and performance uniformity in the thickness direction cannot be guaranteed, and a suitable continuous casting cooling method must be selected to ensure uniform cooling of the surface, minimize internal voids in the slab, and reduce linear shrinkage during solidification; The impurity content of medium and thick plates is more strictly controlled; ③Ensure the compactness of steel ingots and the uniformity of composition, and the finished steel plates guarantee the first-level flaw detection

Method used

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  • Steel HG785D for tower crane and production method
  • Steel HG785D for tower crane and production method
  • Steel HG785D for tower crane and production method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035] The present embodiment takes the production of 240mm thick HG785D steel as an example, and according to the above-mentioned production method, the main production process parameters of the present embodiment are determined as follows:

[0036] During converter smelting, 10Kg of lime, 8Kg of ferromanganese alloy, and 0.6Kg of ferrosilicon alloy are added to each ton of ladle; LF furnace refining is heated for 9 minutes for the first time and 10 minutes for the second time, and the steel loading temperature is 1600°C; Start pouring afterward; the pouring time for the ingot body is 18 minutes, the pouring time for the cap is 7 minutes, the holding temperature is 450°C, and the wide side of the ingot is extruded for 20 mm in the later stage of solidification; the overall cooling and solidification time for the ingot is 5 hours, and the air gap between the ingot mold and the ingot is controlled to 14 mm; heat treatment In the process, 250Kg / t of industrial salt is added to th...

Embodiment 2

[0038] Present embodiment is on the basis of embodiment 1, and processing parameter is adjusted as follows:

[0039] During converter smelting, 10Kg of lime, 9Kg of ferromanganese alloy, and 0.6Kg of ferrosilicon alloy are added to each ton of ladle; the LF furnace refining is heated for 11 minutes for the first time and 9 minutes for the second time, and the steel loading temperature is 1610°C; After pouring, the pouring time of the steel ingot body is 19 minutes, the pouring time of the cap mouth is 8 minutes, and the cooling and solidification time of the overall steel ingot is 5.5 hours; in the heat treatment process, the quenching temperature is 935 ° C, the holding time is 2.4 min / mm, the tempering temperature is 650 ° C, the holding time 4.4min / mm.

Embodiment 3

[0041] Present embodiment is on the basis of embodiment 1, and processing parameter is adjusted as follows:

[0042] During converter smelting, 10Kg of lime, 10Kg of ferromanganese alloy, and 0.6Kg of ferrosilicon alloy are added to each ton of ladle; the LF furnace refining is heated for 12 minutes for the first time and 8 minutes for the second time, and the steel loading temperature is 1620°C; the pouring temperature is controlled at 1558°C, and the molten steel arrives at the station After pouring, the pouring time of the steel ingot body is 20 minutes, the pouring time of the cap mouth is 9 minutes, and the cooling and solidification time of the overall steel ingot is 6 hours; in the heat treatment process, the quenching temperature is 940 ° C, the holding time is 2.5 min / mm, the tempering temperature is 660 ° C, and the holding time is 4.5 min / mm.

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Abstract

The invention discloses steel HG785D for a tower crane and a production method. The steel HG785D for the tower crane comprises the following components of, by weight, 0.14-0.17% of C, 0.38-0.42% of Si, 1.29-1.43% of Mn, less than or equal to 0.012% of P, less than or equal to 0.003% of S, 0.11-0.15% of Nb+V+Ti, 1.17-1.24% of Cr and 1.63-1.78% of Ni. The thickness of the steel HG785D is 160-240mm. The main process comprises the steps of LF refining, vacuum degassing processing, water-cooled copper plate crystallizer ingot mould casting, rolling, ACC laminar cooling and heating processing. The steel HG785D for the tower crane is large in strength and high in yield point, first-grade flaw detection can be ensured, the longitudinal impact energy at minus 20DEG C reaches 189-208J, lamellar tearing resisting performance meets the Z35 grade, microtexture comprises 64-72% of martensite and 19-25% of bainite, and the steel HG785D greatly meets the using demands of ultra-large type tower cranes.

Description

technical field [0001] The invention belongs to the technical field of production of high-strength and extra-thick welded structural steel, and in particular relates to steel HG785D for tower cranes and a production method. Background technique [0002] Tower cranes are the most commonly used and most typical large-scale construction machinery in construction, and super-large tower cranes have been almost monopolized by foreign brands for many years due to their complex key technologies and high safety and reliability requirements. Since 2008, China's hoisting machinery industry has successively developed a series of large-tonnage tower cranes. Super-large-tonnage tower cranes require high-strength and extra-thick welded structural steel materials, which require high strength and high yield points. High-strength and extra-thick welded structural steel for flaw detection and mechanical properties such as HG785D. HG785D provides basic materials for the further development of ...

Claims

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Application Information

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IPC IPC(8): C22C38/50C22C38/48C22C38/46B22D7/00B22D7/12C21D8/02C21C7/06
CPCY02P10/20
Inventor 朱书成唐郑磊许少普李忠波崔冠军赵迪康文举
Owner NANYANG HANYE SPECIAL STEEL CO LTD
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