TPT July 2011

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(4) Surface engineering option: the ways included plating, seeping, spraying, coating and so on are used in difference piece and the result is successful, the surface layer is too thin so the application limit is restricted. References [1] Yang Xiuqin ‘Actuality, Problems and Developing Foreground of China’s Steel Pipe Industry’ Xi An: colloquia for third annual meeting of 5 th session of pipe science committee steel rolling academy of China metallurgy academy. [2] Fu Hanguang, Xing Jiandong ‘High Speed Steel Roll Manufacture Technique’ Beijing: metallurgy industry publishing house. 2007.6 [3] Lin Huiguo ‘Pocket World Steel Grade Manual’ Beijing: mechanical industry publishing house 2003.6 [4] Chen Huahui, Xing Jiandong, Li Wei ‘Wear Resistance Material Applying Manual’ Beijing: mechanical industry publishing house 2006.8 [5] Association of iron and steel engineers ‘The Making, Shaping and Treating of Steel’ Printed in USA by Herbick & Held Pittsburgh, Pennsylvania, 1985 [6] Li Jionghui, Lin Decheng ‘Metallograph of Metal Material’ Beijing: mechanical industry publishing house 2006.6

high chromium alloy casting rolls have advantages in method and cost of manufacture. The effects of saving energy and material are remarkable through utilising high chromium alloy casting roll.

6. The discussion on development trend 6.1 Casting roll and forging roll Casting roll and forging roll separately have advantages and disadvantages. For special-shaped roll, which have the features of complex shape, more sizes, small batch, the casting high chromium alloy roll process have notable results for saving energy and saving raw material. Certainly the high chromium alloy-casting roll is still to require further perfection. 6.2 Centrifugal casting method and conventional casting method The roll with centrifugal casting method has a lot of advantages over the roll with convention casting method in the qualities. After the 1990s the roll with centrifugal casting method had a bigger development used in plate and strip steel production at home, but it is difficult to popularise in the production of welding pipe roll. The main cause is that the structure and shape are different between roll used in welding pipe production and roll used in plate and strip steel production, one piece of drawing of welding pipe roll is only to produce one or two pieces, so it is not economic to do a centrifugal casting mould. If utilising conventional casting methods it is too difficult to do high chromium alloy casting and is easy to produce a defect. If utilising a centrifugal casting method it is requested to utilise special centrifugal casting methods. If utilising conventional casting methods a series of technical methods must be used to ensure quality of casting piece. 6.3 Bimetal complex method and single metal method Whether utilising a bimetal complex method or single metal method it is important to think about the shape, working condition and the working layer thickness of rolls. The aim of utilising bimetal complex method is to save the noble metal and to increase the whole strength and toughness of the roll, this is as a principle. The bimetal complex method also has many ways that are better to accord with the production requirement of steel pipe roll and cold forming steel roll, but which need further research and practice. The options are as follows: (1) The metallurgical combining option: the centrifugal and non- centrifugal complex casting. At the present a lot of roll for steel plate and steel strip are produced by centrifugal complex casting. Now this technology has been perfected day by day, but the material for working layer is gradually developed towards high alloying, high wear resistance and so on. (2) Inlay complex casting option: the way has also got success under the condition of lower load. (3) Machine combining option: now the most of straightening roll for steel pipe has been changed from whole forging structure of roll and axle to dividing structure of roll sleeve and axle. Through interference fit and differential temperature mounting the application result is better. The roll for PQF steel pipe mill is also changed from whole body structure to dividing structure of roll sleeve and axle, and the result is successful.

Shandong Province Sifang Technical Development Co Ltd – China

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