Application of asymmetric roll pass for improving roundness of ultra-thick steel tubes

the aid of commercially available software MSC.SuperForm, a 3-D finite element model has been established to simulate the rolling process of steel tubes on the stretch reducing mill (SRM) with group centralized differential drive in certain factories. A special effort was made to analyze the fluctuation of transverse wall thickness uniformity. It was found that the wall thickness of each stand was accumulated in the original pass 50°~60° along the circumferential direction, which caused the formation of the inner hexagon defects and worsen. In view of this, this paper proposes a modified roll pass design method which uses the interactive technology of CAD graph curve and MATLAB equation. By means of decreasing the lateral curvature of roll pass contour curve to enlarge the contact length between the tube and groove, also the rolling process using the new pass system were simulated and analyzed. The results indicate that the design of such polygonal roll pass can be effective in improving the inner hexagon defects.

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Mechanical Analysis on the Inner Surface Crack of Modified 9Cr-1Mo Seamless Steel Tubes Rolled by Mandrel Mill

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.97-101.3070 ◽

2010 ◽

Vol 97-101 ◽

pp. 3070-3074

Author(s):

Sheng Zhi Li ◽

Jie Xu ◽

Yuan De Yin ◽

Hui Chao Su

Keyword(s):

Surface Crack ◽

Production Efficiency ◽

Circumferential Stress ◽

Rolling Process ◽

Mechanical Analysis ◽

Steel Tube ◽

Roll Pass ◽

Steel Tubes ◽

Inner Surface ◽

Seamless Steel

The inner surface crack (ISC) defect easily occurs in seamless modified 9Cr-1Mo steel tubes rolled by the mandrel mill with high production efficiency. The reason for the formation of the ISC lies in both the properties of deformed material and rolling conditions. With the aid of commercial FE code MSC.SuperForm, the rolling process of modified 9Cr-1Mo seamless steel tube produced by the Mandrel Mill of Bao Steel in China was simulated, focusing on mechanical analysis of deformed metal. It was found from the simulation that the metal on the inner surface of the tube, in the position of 0 or 90 of the roll pass, experiences strong tensile stresses, especially the circumferential stress, which is closely related .to the strain behavior governed by the two-high pass caliber of the mandrel mill. Therefore an optimal design of the roll pass can be realized to decrease the tensile stress so as to relax the tendency to the ISC, which has been confirmed by the tests in Steel Tube & Pipe Company of Bao Steel.

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Pyrolytic carbon filaments and associated catalytic particles formed in steel tubes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100113196 ◽

1984 ◽

Vol 42 ◽

pp. 662-663

Author(s):

Y. L. Chen ◽

J. R. Bradley

Keyword(s):

Stainless Steel ◽

Carbon Steel ◽

Catalyst Particle ◽

Pyrolytic Carbon ◽

Plain Carbon Steel ◽

304 Stainless Steel ◽

Hydrocarbon Gases ◽

Steel Tubes ◽

Filamentous Carbon ◽

Carbon Filaments

Considerable effort has been directed toward an improved understanding of the production of the strong and stiff ∼ 1-20 μm diameter pyrolytic carbon fibers of the type reported by Koyama and, more recently, by Tibbetts. These macroscopic fibers are produced when pyrolytic carbon filaments (∼ 0.1 μm or less in diameter) are thickened by deposition of carbon during thermal decomposition of hydrocarbon gases. Each such precursor filament normally lengthens in association with an attached catalyst particle. The subject of filamentous carbon formation and much of the work on characterization of the catalyst particles have been reviewed thoroughly by Baker and Harris. However, identification of the catalyst particles remains a problem of continuing interest. The purpose of this work was to characterize the microstructure of the pyrolytic carbon filaments and the catalyst particles formed inside stainless steel and plain carbon steel tubes. For the present study, natural gas (∼; 97 % methane) was passed through type 304 stainless steel and SAE 1020 plain carbon steel tubes at 1240°K.

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