日本金属学会誌

J. Japan Inst. Met. Mater, Vol. 79, No. 3 (2015),
pp. 142-145

Effect of Surface Structure and Hydrogen on the Fatigue Strength of Electroless Nickel-Phosphorus Plated Al-2%Cu and Al-2%Zn Alloys

Norihito Nagata1, Teruto Kanadani1, Keitaro Horikawa2, Kouji Murakami3 and Makoto Hino4

1Department of Mechanical Systems Engineering, Faculty of Engineering, Okayama University of Science, Okayama 700-0005
2Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science, Osaka University, Toyonaka 560-8531
3Industrial Technology Research Institute of Okayama Prefecture, Okayama 701-1296
4Department of Mechanical Systems Engineering, Faculty of Engineering, Hiroshima Institute of Technology, Hiroshima 731-5193

Abstract:

In this study, the effect of the surface structure and hydrogen on the fatigue strength of electroless Ni-P plated Al-2%Cu and Al-2%Zn alloys was investigated. As the results, the following points were clarified. (1) Large precipitates (size) were recognized near the specimen surface of the furnace-cooled Al-Cu alloy, but these were not recognized in the furnace-cooled Al-Zn alloy. (2) Fatigue strength of the Al-Cu alloy specimen subjected to Ni-P plating after a furnace cooling treatment was overall reduced rather than one of the non-processed specimens. (3) Fatigue strength of the Al-Zn alloy specimen subjected to Ni-P plating after the furnace cooling treatment showed a clear increase in comparison to one of non-processed materials. (4) In both the Al-2%Cu and Al-2%Zn alloy specimens subjected to Ni-P plating after the furnace cooling treatment, a clear hydrogen desorption was recognized. On the other hand, there was only hydrogen desorption from a few of the non-processed specimens.
It is considered that the poor fatigue strength of the plating materials is mainly due to the interaction between the surface precipitates and hydrogen gas. [doi:10.2320/jinstmet.JC201414]


(Received 2014/11/12)

Keywords:

aluminum-copper alloy, aluminum-zinc alloy, nickel-phosphorus plating, fatigue strength, aging, surface precipitate, hydrogen gas


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