Conditions for Sticking Friction between Aluminium Alloy AA6060 and Tool Steel in Hot Forming

Abstract:

The frictional conditions between an aluminium AA6060 alloy and tool steel in hot bulk forming have been investigated. The compressive-rotational method for frictional measurements, presented herein, represents an innovative approach for defining the thermo-mechanical conditions required for sticking friction at the interface between the two metals. Aluminium disks with inserted contrast material were subjected to a variety of pressures and rotated at one end at temperatures ranging from 250 °C to 500 °C. Visual inspection of the surfaces in combination with sectioning of the deformed disks formed a method for studying how different factors affect a stick-slip criterion in metal forming. It was found that the normal contact pressure required for sticking to occur was strongly dependent on the instantaneous temperature. When comparing the normal contact pressure q with the characteristic shear strength k of the aluminium alloy, q/k > 0.6 yielded sticking friction for temperatures above 300 °C, while a ratio of 0.7 was required for the lower temperatures.

• Periodical: Key Engineering Materials (Volume 491)
• Pages: 121-128
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.491.121
• Online since: September 2011
• Authors: F. Widerøe, Togeir Welo
• Keywords: Elevated Temperature, Extrusion, Friction, Pressure

References

[1] P. Saha, Aluminum extrusion technology. Materials Park, OH: ASM International, (2000).

[2] S. Abtahi, Friction and interface reactions on the die land in thin-walled extrusion, doctoral, The Norwegian Institute of Technology, The University of Trondheim, Norway, Trondheim, Norway, (1995).

DOI: 10.15714/scandpsychol.2.e8

[3] T. Welo, et al., Friction in the bearing channel of aluminium extrusion dies, Proceedings of the 15th International Symposium of Deformation Processes, (1994).

[4] E. Orowan, The calculation of roll pressure in hot and cold flat rolling, Proceedings of the Institution of Mechanical Engineers, vol. 150, pp.140-167, (1943).

DOI: 10.1243/pime_proc_1943_150_025_02

[5] H. S. Valberg, Applied metal forming: Including FEM-analysis: Cambridge University Press, (2009).

[6] F. P. Bowden and D. Tabor, The Friction and Lubrification of Solids: Oxford Univ. Press, (1950).

[7] T. Wanheim, Friction at high normal pressures, Wear, vol. 25, pp.225-244, (1973).

DOI: 10.1016/0043-1648(73)90074-4

[8] K. Colligan, Material Flow Behavior during Friction Stir Welding of Aluminum, Welding Journal, vol. July, pp. 229s-237s, (1999).

[9] T. Seidel and A. Reynolds, Visualization of the material flow in AA2195 friction-stir welds using a marker insert technique, Metallurgical and Materials Transactions A, vol. 32, pp.2879-2884, (2001).

DOI: 10.1007/s11661-001-1038-1

[10] V. S. Zhernakov, et al., A numerical modelling and investigations of flow stress and grain refinement during equal-channel angular pressing, Scripta Materialia, vol. 44, pp.1765-1769, (2001).

DOI: 10.1016/s1359-6462(01)00796-5

[11] V. Vazquez and T. Altan, New concepts in die design - physical and computer modeling applications, Journal of Materials Processing Technology, vol. 98, pp.212-223, (2000).

DOI: 10.1016/s0924-0136(99)00202-2