TPT-January-2015

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January 2015 91
Shandong SiFang Technical Development Co Ltd Article
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.
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 .
Figure 8: Average friction coefficient Figure 9: Volume wearing capacity Figure 10: Average volume wearing capacity
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:
Website:
Figure 11: Surface wear condition of new crimping dies