TPT March 2018

AR T I C L E

Shandong Province SiFang Technical Development Co, Ltd

Analysis and selection of material for rolls used to produce welding steel pipe By Yuan Houzhi, Shandong Province SiFang Technical Development Co, Ltd, China

1. Overview of welded pipe roll materials The material used in a traditional welded pipe roll is alloy-forged steel. The USA designs rolls to use D2 and H13; Germany designs rolls to use X155CrVMo12-1 and X40CrMoV5-1; and Japan designs rolls to use SKD11 and SKD61. China first developed the standard YB/T 128-1997 ‘Technical conditions of welded pipe roll’ in 1997, and the materials used adopted GCr15, Cr12, Cr12MoV, 35CrMoV, 40Cr, 4Cr5MoSiV1, 3Cr2W8V and 65Mn. In 2014 China developed the national standards GB/T1299-2014 ‘Tool and die steel’, while the roll material used 9Cr2V, 9Cr2Mo and 9Cr2MoV. Forged steel rolls made from materials D2, X155CrVMo12-1, SKD11 are some of the most advanced in the world, and are equivalent to the forged steel Cr12Mo1V1 of China, rather than the material Cr12MoV. Roll material H13, X40CrMoV5-1, SKD61 is the equivalent to forged steel 4Cr5MoSiV1 used in China. Cr12Mo1V1-D2, X155CrVMo12-1, SKD11 is widely used as high-quality cold work die steel around the world. In the early 21 st century, domestic cold-rolled strip in China using forged Cr12Mo1V1 rolls matched the performance of The China national standard GB/T 31936-2015 ‘Rolls for welding steel pipe’, which was first implemented in June 2016, adapts to recent progress and developments in the welding pipe and roll industry. In accordance with the variable service conditions of rolled material now used for roll classifications, the new standards more accurately meet the requirements of the rolling steel industry and help users to select the correct rolls for the correct task. The standard also adds grades of roll steel that reach the current international advanced level and removes non- applicable material from the list. Continuous deformation rolling technology, characterised by the name ‘roll’, is the key technology used by the modern large-scale, high-speed, continuous automatic rolling steel industry. Rolls are an important large consumption tool for rolling production, which is a prerequisite for the development of a company’s modern rolling technology.

imported products and improved the brightness of the steel plate, but there are no reports regarding production of forged Cr12Mo1V1 welded pipe roll in China – only the production of diameter less than Φ600mm forged Cr12MoV roll. Henan University of Science and Technology and Xinxiang Kaidi Roll Co Ltd tests also proved the difference of the wear resistance between forged Cr12MoV roll and D2, X155CrVMo12-1, SKD11 forged steel roll. At the end of the 20 th century, high chromium alloy roll for welding steel pipe made in China replaced imported forged steel roll competing with the USA, German and Japanese forging steel roll and fully achieved the level of D2, X155CrVMo12-1, SKD11 for forged roll. High chromium alloy rolls have since been exported to a number of countries and successfully applied by dozens of large-scale domestic pipe manufacturing enterprises in China. 2. The type and material of roll for welding steel pipe in China national standard GB/T 31936-2015 2.1 Characteristics of welded pipe roll Welded pipe is a non-cylindrical variable diameter shaped roll. The main feature is that it has a wide variety of specifications and most of the drawings are made using only one or two

185

www.read-tpt.com

MARCH 2018