Effects of Water-Cooling on the Mechanical Properties and Microstructure of 5083 Aluminum Alloy during Flame Straightening

Aluminum alloy 5083 is widely used in the fabrication of marine vessels. This paper presents the difference in mechanical properties and microstructure between natural-cooling and water-cooling after flame straightening. Under the synchronous water-cooling process, the peak temperature of the heating center was unchanged, but the peak temperatures of the other areas decreased obviously and the cooling rate increased substantially. The microhardness of the rectified area was lower than that of the base metal. The average microhardness decreased about 4.4 HV when using synchronous water-cooling, whereas the average microhardness of the specimen without using water-cooling was 11.6 HV lower than the base metal. Tensile test results show that the yield strength and the ultimate strength of synchronous water-cooling specimen increased 9.16 MPa and 1.64 MPa on average, but the elongation rate decreased compared with the specimen only under flame straightening. The results of metallographic tests show that the grain growth tendency and precipitation phase size and quantity reduced after using synchronous water-cooling.