TPT-January-2015

Article

Shandong SiFang Technical Development Co Ltd

Figure 8: Average friction coefficient

Figure 9: Volume wearing capacity

Figure 10: Average volume wearing capacity

5 Conclusion The developed high chromium die steel has fully met the service condition requirements of crimping dies. Its testing and usage results have demonstrated that the quality level of the new dies have reached that of the forged alloy steel dies made in Germany and that the new dies can substitute former crimping dies competently, enhancing the manufacture level of Chinese advanced dies used in production of UOE welded pipe. The development and application of new crimping die steel has made Baosteel and Sifang explore a lot in mastering core manufacture technology of crimping dies for UOE welded pipe formation. In future, the study will focus on design of the working surface profile and material improvement in order to enlarge the producible specification range of UOE welded pipe plant, extend the lifespan of dies and boost a controllable level of pipe forming processing. References [1] Wang San-yun, 2000, “Technical development overview of foreign large diameter LSAW pipe production”, Welded Pipe and Tube , Vol. 23, pp. 50-58. [2] Sun Rui-hua, 2000, ”Production and present situation of UOE welded pipe”, Welded Pipe and Tube , Vol. 23, pp. 24-39. [3] Liu Jing-lei, Xie Shi-qiang, Ruan Feng, 2005, “Inverse solution of springback in bending and its application to optimal design for prebending UOE pipe”, Forging & Stamping Technology , Vol. 2, pp. 36-39. [4] Li Hong, 2006, “Crimping processing of LSAW pipe production line”, Welded Pipe and Tube , Vol. 29, pp. 55-57. [5] Yang Qiang, 2012, “Springback analytic and process parameters optimization of plate edge preflex for the forming of large diameter longitudinal seam welded pipe”, Master’s Degree Thesis, Yanshan University, Qinhuangdao, China. [6] Yin Jing, 2011, “Springback theory of small curvature plane bending and experimental verification”, Ph.D. Thesis, Yanshan University, Qinhuangdao, China. [7] Yuan Hou-zhi, 2006, “Roll made of cast high chromium iron or steel in welded steel pipe production”, ZL200610104942.X , Patent , China. [8] “EN 12680-2: 2003, Founding-Ultrasonic examination-Part 2: Steel castings for highly stressed components”, Standard . [9] “EN1369: 1997, Founding Magnetic particle inspection”, Standard . [10] “EN1371-1: 1997, Founding-Liquid penetrant inspection Part 1: Sand, gravity die and low pressure die castings”, Standard .

wearing ring material and size, and testing sample block size. The testing sample blocks have been made of five kinds of materials, three blocks per kind, and the materials are listed as follows:

No.

A

B

C

D

E

Material

German die steel

American D2

Japanese SKD11

High chromium die steel- A

High chromium die steel- B

The test results show that the new crimping dies made of high chromium die steel are almost equivalent to the dies made in Germany in the wear-resisting property.

4 Field application of new crimping dies

After completing die manufacture of high chromium die steel, non-destructive testing has proved that the new crimping dies have satisfied the requirements of ultrasonic testing standards [8] , the Level 2 requirements of magnetic particle inspection standards [9] and the Level 2 requirements of PT inspection standards [10] and that there are no crack defects in the surface or near the surface. After delivery of the new crimping dies, the die manufacturing precision and the physical and chemical properties have met the scheduled requirements in the die assembly and service in Baosteel. In the volume experimental process, the forming quality indexes, the surface quality and the marginal extension after crimping are all in line with the quality control requirements. From January 2014 to July 2014, 3,978 pipes have been formed with the new crimping dies; after off-line inspection, there has been uniform wear in the die surface and no surface defects affecting the quality of welded pipes and the die lifespan, as shown in Figure 11; NDT results have proven to be good.

Shandong Province SiFang Technical Development Co Ltd

University Science & Technology Park of Jinan High-Technology Industrial Development Zone, No 750 of Shunhua Road, Jinan, China Tel : +86 531 88876609, 88876629 Fax : +86 531 88876693 Email : sdsf@vip.163.com Website : www.cnsdsf.com

Figure 11: Surface wear condition of new crimping dies

91

www.read-tpt.com

J anuary 2015