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Bearing roller of 4200 mm or above wide and thick plate rolling mill and manufacturing process of bearing roller

A technology of back-up rolls and plate rolling mills, which is applied in the direction of manufacturing tools, rolls, metal rolling, etc., can solve the problems of white spots on back-up rolls, reduced toughness at the center of back-up rolls, and short service life, and achieve good wear resistance and resistance Fatigue performance, reduce the risk of fatigue spalling, and improve the feasibility of the process

Active Publication Date: 2018-07-13
CHINA ERZHONG GRP DEYANG HEAVY IND
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  • Abstract
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AI Technical Summary

Problems solved by technology

[0005] At present, there are very few manufacturers of extra-large backup rolls in the world. The carbon content of the traditional steel materials used is 0.70% to 1%, the chromium content is 0.9 to 1.6, and it does not contain vanadium. There is no requirement for the hydrogen content in the steel. Therefore, there are the following defects: (1) Since the steel ingot used for the extra-large backup roll is 340t to 450t, the carbon content of this material is very high. With the increase in size of the steel ingot, the segregation of carbon elements is quite serious. The carbon content can reach more than 1.5%, and large block carbides and severe network carbides are formed in the material, which are not easy to eliminate, so that the back-up roll often breaks during heat treatment and use; (2) Due to the low content of alloy elements in the material, The microstructure is pearlite, the hardness of the surface of the roller body and the working layer is low, HS45~HS50, the wear resistance is poor, pits and early peeling often appear on the roller surface, the consumption of the backup roller is large, and the service life is short; (3) due to the Large block carbides and severe network carbides are formed, the toughness is poor, and fatigue cracks often appear on the surface during use; (4) Due to the relatively low strength and hardness of pearlite materials, lower hardness must be used in heat treatment for performance. Tempering at a high temperature increases the residual stress of the back-up roll, and there is no requirement for the hydrogen content in the steel, often resulting in white spots or fractures in the back-up roll due to excessive stress and high hydrogen content
[0006] Wang Lidi. Analysis on the manufacturing of back-up rolls for wide and heavy plate mills[J]. Yizhong Technology, 2008(4):56-58 disclosed that the material 70Cr3Mo and 70Cr3NiMo steel ingots are seriously segregated, which reduces the toughness of the center of the back-up rolls and the ability to resist accidents.

Method used

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  • Bearing roller of 4200 mm or above wide and thick plate rolling mill and manufacturing process of bearing roller
  • Bearing roller of 4200 mm or above wide and thick plate rolling mill and manufacturing process of bearing roller

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preparation example Construction

[0056] Further, the preparation method of the backup roll includes the following steps:

[0057] (1) Smelting and ingot casting: molten steel is roughly smelted, refined, alloyed, and vacuum cast into ingots; wherein, the chemical composition of the steel is as above.

[0058] Preferably, the preparation method of the backup roll also includes the following steps:

[0059] (2) Forging: heating the vacuum steel ingot, cutting off the harmful part of the ingot tail, upsetting and elongating, cutting off the harmful part of the riser, and forging a back-up roll blank;

[0060] (3) Heat treatment after forging: normalizing + spheroidizing annealing + tempering;

[0061] (4) Rough machining: rough machining of the forging blank;

[0062] (5) Final heat treatment: the process form is quenching + tempering.

[0063] Preferably, the rough refining of the molten steel in step (1) adopts an electric furnace, the alloying and refining of the molten steel adopts a ladle refining furnac...

Embodiment 1

[0074] (1) Smelting and ingot casting: molten steel is initially smelted in an electric arc furnace, then poured into a ladle refining furnace for refining and alloying, and then poured into a 450t large steel ingot by dripping and degassing in a vacuum ingot casting chamber, and the hydrogen content in the steel Reduced to below 1ppm.

[0075] The mass percent of its chemical composition is as follows: C=0.59, Si=0.43, Mn=1.24, Ni=0.34, Cr=2.06, Mo=0.54, V=0.25, P=0.15, S=0.008, Cu=0.10, H= 0.8ppm, the balance is iron and other unavoidable impurities.

[0076] (2) Forging: After heating the steel ingot, cut off the harmful part of the ingot tail, upsetting and elongating, cut off the harmful part of the riser, and forge the back-up roll blank;

[0077] (3) Heat treatment after forging: normalizing + spheroidizing annealing + tempering;

[0078] (4) Rough machining and ultrasonic flaw detection: process the forging blank according to the rough machining drawing, see the roug...

Embodiment 2

[0081] (1) Smelting and ingot casting: The molten steel is initially smelted in an electric arc furnace, then poured into a ladle refining furnace for refining and alloying, and then poured into a 340t large steel ingot by dripping and degassing in a vacuum ingot casting chamber, and the hydrogen content in the steel Reduced to below 1ppm, its chemical composition (mass percentage) is as follows: C=0.62, Si=0.38, Mn=1.18, Ni=0.34, Cr=1.96, Mo=0.49, V=0.20, P=0.016, S=0.006, Cu = 0.008, H = 0.9ppm, and the balance is other trace elements in iron and steel scrap.

[0082] (2) Forging: After heating the steel ingot, cut off the harmful part of the ingot tail, upsetting and elongating, cut off the harmful part of the riser, and forge the back-up roll blank;

[0083] (3) Heat treatment after forging: normalizing + spheroidizing annealing + tempering;

[0084] (4) Rough machining and ultrasonic flaw detection: process the forging blank according to the rough machining drawing, see ...

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Abstract

The invention relates to a bearing roller of a 4200 mm or above wide and thick plate rolling mill and a manufacturing process of the bearing roller, and belongs to the technical field of forging. Thebearing roller comprises, by mass percent, 0.50 to 0.65% of C, 0.17 to 0.50% of Si, 0.80 to 2.0% of Mn, 0.30 to 0.70% of Ni, 1.60 to 2.5% of Cr, 0.30 to 1.00% of Mo, 0.10 to 0.35% of V, not larger than 0.020% of P, not larger than 0.010% of S, not larger than 0.15% of Cu, not large than 1.0 ppm of H, and the balance iron and inevitable impurities. The carton content of a new material of the super-huge type forged steel bearing roller is low, alloy elements of chromium, nickel and vanadium are added, the microstructure comprises bainite and pearlite, the strength and toughness of the material are improved, the solidification segregation of a large steel ingot is reduced, the comprehensive performance is good, and the service life is long.

Description

technical field [0001] The invention relates to a back-up roll and its manufacturing process, in particular to a back-up roll of a 4200mm thick plate rolling mill and its manufacturing process, and belongs to the technical field of forging. Background technique [0002] Wide and thick plates are important strategic materials, widely used in large ships over 100,000 tons, large-diameter oil and gas longitudinal welded pipes, and weapon armor, structural steel for giant bridges, structural steel for offshore drilling platforms, containment shells for nuclear power plants, large dam gates, and high-pressure boilers Steel plates, steelmaking blast furnace shells, large oil and gas storage tanks, large mechanical structural steels, die steels, super high-rise buildings and other fields, especially in the field of military shipbuilding, large single-weight wide and thick plates are indispensable. [0003] Back-up rolls are key stress-bearing parts and consumable spare parts on wid...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/44C22C38/46C22C38/02C22C38/04C22C38/42B21B27/03B21J5/00B21J5/08C21D8/00
CPCB21B27/03B21J5/00B21J5/002B21J5/08C21D8/005C22C38/02C22C38/04C22C38/42C22C38/44C22C38/46
Inventor 蒋新亮赵欣杨萍陈先毅李英赵秀清
Owner CHINA ERZHONG GRP DEYANG HEAVY IND
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