This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
7/28/2019 Variation in Peel Strength and Surface Roughness
Journal of Materials Processing Technology 210 (2010) 560–563
Contents lists available at ScienceDirect
Journal of Materials Processing Technology
j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / j m a t p r o t e c
Effects of processing parameters on the bond strength of Cu/Cu roll-bonded strips
Mohsen Abbasi, Mohammad Reza Toroghinejad ∗
Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran
a r t i c l e i n f o
Article history:
Received 19 July 2009
Received in revised form 26 October 2009
Accepted 8 November 2009
Keywords:
Copper
Cold roll bonding
Peel strength
a b s t r a c t
Roll bonding, widely used in manufacturing large layered composite sheets, is a solid phase method for
bonding similar or dissimilar metals by rolling. In this study, the effects of process parameters such as
rolling reduction, rolling temperature, rolling speed, initial thickness of strip, and surface roughness on
the bond strength between two-layer strips of Cu/Cu were investigated. The strips were subjected tochemical and mechanical cleaningprior to rolling, andafterrolling, bond strengthswere measured using
the peeling test. It was observed that increased reduction, rolling temperature, strip width, and surface
roughness led to an increase in peeling strength while increased rolling speed and initial thickness of
strips caused peeling strength to decrease. Results also showed that increasing the initial thickness of
strength at interfaces. The bond strength is observed to decrease
as the speed is increased, leading to shorter times of contact. The
increased bond strength can further be related to the insufficient
extrusion of virgin metals through cracks resulting from the frac-
ture of the oxide film or from the work-hardening layer in a shorttime; thus, it is difficult to bring two surfaces with large areas into
contact. In addition, high speeds can result in width changes on
the top and in other parts of the specimens. Rolling speed has a
twofold effect on the bond. It affects the interface temperature;
high speed causes high temperature that is good for the bond. It
simultaneously affects the effective time for bonding. The bond
strength is observed to decrease as thespeed increases,leading to a
shorter time of contact. Our results indicate that the time is a more
important parameter for rolling speed effects than is temperature.
3.5. Effect of surface roughness on bond strength
Fig.9 shows theeffect of surface roughnesson thebondstrength
of Cu/Custrips.The initial surface roughness (prior to scratch brush-ing)ofthesampleswasRa = 0.25malongboththerollingdirection
and the transverse direction. Surface roughening by scratch brush-
ing greatly improved the bonding quality, reduced the pressure
required to initiate bonding, and gave some of the highest bond
strengths. By increasing surface roughness of the sheets, the aver-
age peel strength or bond strength increased. This is because work
Fig. 9. Variation in peel strength of two-layer strips of Cu/Cu versus surface rough-
ness.
hardening of the sheets increased and caused a more brittle layer
to form on the surface that could be broken more easily so that the
virgin metal could be extruded more easily as well.
4. Conclusions
The bond strength between two-layered Cu/Cu strips in the roll
bonding process was measured using the peeling test. The follow-
ing conclusions may be drawn from the present work:
1. Bond strength is improved by increasing thickness reductions,
rolling temperature, and surface roughness of the strips.
2. Bond strength in Cu/Cu stripsdecreases by increasing the rolling
speed and the initial thickness of strips.
3. Increasing the initial thickness of strips decreases the value of
threshold deformation to accomplish the bonding between the
layers.
References
Bay, N., 1986. Cold welding: Part I. Characteristic, bonding mechanisms, bondstrength. J. Met. Constr. 18 (6), 369–372.
Bay, N., Zhang, W., 1994. Influence of different surface preparation on the bondformation in cold pressure welding. In: Proceedings of the Second EuropeanConference on Joining Technology, Italy, pp. 88–379.
DaneshManesh, H.,KarimiTaheri, A.,2004.Studyof mechanismsof coldroll weldingof aluminum alloy to steel strip. J. Mater. Sci. Technol. 20 (8), 1064–1068.
Hwang, Y.M., Kiuchi, M., 1992. Analysis of asymmetrical complex rolling of multi-layer sheets by upper bound method. J. Chin. Soc. Mech. Eng. 13 (1), 33–45.
Mohamed, H.A., Washburn, J., 1975. Mechanism of solid state pressure welding.Weld. J., 302–310.
Pan, D.,Gao,K., Yu, J.,1989. Cold roll bonding of bimetallic sheet and strips. J. Mater.Sci. Technol. 5, 934–939.
Parks, J.M., 1953. Recrystallization in welding. Weld. J., 209–221.Peng, X.K., Heness, G., Yeung, W.Y., 1999. Effect of rolling temperature on inter-
face and bond strength development of roll bonded copper/aluminum metal. J.Mater. Sci. 34, 277–281.