Effect of Various Types of Plating on Mechanical Properties of 2017 Aluminum Alloy

Abstract

Effects of various surface treatments on the mechanical properties of the 2017-T4 aluminum alloys were evaluated using Slow Strain Rate Technique（SSRT）tensile tests and rotary bending fatigue tests. For the 2017-T4 alloy, Thermal Desorption Analysis（TDA）analysis revealed that each plating causes hydrogen absorption into the substrate. Effects of the various plating types on the maximum strength, fracture strength, and elongation at breakage of the 2017-T4 alloy in SSRT tensile tests were not found to be significant in any case. However, the fatigue strength of the specimen plated with high-phosphorus-type Ni-P was markedly lower than that of the un-plated specimen. This reduction in fatigue strength might be attributable to hydrogen embrittlement caused by introducing hydrogen into the specimen during plating. Therefore, when repetitive loads are applied, caution is in order when applying Ni-P plated high phosphorus types to 2017-T4 alloy.