Stress corrosion cracking behavior of friction-stir-welded Al 6061-T651
- PDF / 281,186 Bytes
- 4 Pages / 612 x 792 pts (letter) Page_size
- 94 Downloads / 152 Views
During the past 10 years, a considerable amount of research effort has been conducted on the friction stir welding (FSW) technique, particularly for the joining of Al alloy plate. The FSW process is at present entering into the initial stage of commercialization, and the corrosion problem with the friction-stir-welded material has become the concern of many researchers.[1–4] Previously, a considerable number of reports have been published on the corrosion behavior of frictionstir-welded Al alloys, demonstrating that the resistance to corrosion in the friction-stir-welded Al alloys is unexpectedly high considering the complex microstructural evolution during the FSW process. Hannour et al. reported that the heat-affected zone (HAZ) was the region susceptible to corrosion of friction-stir-welded Al alloys.[5] At present, the number of studies on stress corrosion cracking (SCC) is, however, relatively limited, compared to the general corrosion behavior of the friction-stir-welded Al alloys. The objective of the present study was therefore to examine the SCC behavior of friction-stir-welded Al 6061-T651 alloy in 3.5 pct NaCl solution using a slow strain rate testing technique.
SUNGGON LIM, Graduate Student, and SANGSHIK KIM, Professor, are with Division of Materials Science and Engineering, Engineering Research Institute, Gyeongsang National University, Chinju 660-701, Korea. Contact e-mail: [email protected] CHANG-GIL LEE, Senior Researcher, and SUNGJOON KIM, Principal Researcher, are with Materials Engineering Department, Korea Institute of Machinery and Materials, Changwon 641-010, Korea. Manuscript submitted March 29, 2004. METALLURGICAL AND MATERIALS TRANSACTIONS A
The 4-mm-thick Al 6061-T651 alloy plates, manufactured at Kaiser Aluminum Co. (Richmond, VA), were used in the present study. The rotating and welding speed, respectively, were 1600 rpm and 0.3 mpm (m/min), respectively. Figure 1 shows the representative microstructure of friction-stir-welded Al 6061-T651 sectioned perpendicular to the traversing direction. As reported previously,[6,7] typical dynamically recrystallized zone (DXZ), thermomechanically affected zone (TMAZ), HAZ, and parent material (PM) were observed. For the study of pitting corrosion behavior of each microstructure, polarization tests were performed in 3.5 pct NaCl aqueous solution without deaeration. The polarization tests were conducted using a PAR (Oak Ridge, TN) model Versa Stat II potentiostat at a scan rate of 1 mV/s using the Ag/AgCl reference electrode and platinum counter electrode. The surface area of the specimen for the polarization test was 0.4 0.6 cm2, which was smaller than the standard size due to the size limitation of the specimen. The round bar tensile specimens were used for the slow strain rate tests, which were prepared with the tensile direction perpendicular to the welding direction, so that the weld zone is located in the middle of the specimen. The in-situ slow strain rate tests were performed either in air or in 3.5 pct NaCl aqueous solution at a nominal str
Data Loading...
