One of the friction-stir welding (FSW) limitations is joining thin sheets in sheet-metal manufacturing. To solve this limitation, thicker sheets can be welded with FSW and then rolled to a thinner ...thickness. This can improve the mechanical properties and save the weld zone soundly. In this work, 3-mm aluminum sheets were joined with FSW. The microstructure and mechanical properties of the samples were assessed at various rotational speeds (w) and travel speeds (v). Then, the welded samples were cold worked (CW) by rolling them at different percentages so that the samples were 2 mm and 1 mm thick. The effects of welding and post rolling on the mechanical properties and a failure analysis were deliberated. It was shown that welding reduces the transverse ultimate tensile strength (UTS) of FSWed samples by up to 29 % compared to the UTS of the base metal (BM), while rolling FSWed samples increased the UTS of the cold-worked FSWed samples by up to 94.7 % in comparison to the UTS of FSWed samples. Also, during the tensile test of the specimens FSWed at a lower travel speed, a fracture occurred at the stir zone (SZ)/thermo-mechanically affected zone (TMAZ) interface, on the advancing part; however, at a higher travel speed, it occurred at the interface of the heat-affected zone (HAZ) and TMAZ, on the retreating part. Moreover, during the tensile test of the cold-worked FSWed samples, the failure took place at the HAZ and the interface of the SZ and TMAZ, respectively. The UTS was risen by increasing the cold work. The UTS of a specimen FSWed at 50 mm/min and 1200 min–1 went up from 76 MPa to 124 MPa due to 33-% cold work and to 148 MPa due to 66-% cold work; meanwhile, the fracture occurred at the SZ/TMAZ interface or TMAZ of most of the post-rolled FSWed samples.
The objective of this work was to study the suitability of three types of cast iron for the manufacture of a ship engine: EN-GJS-500-7U for the manufacture of the engine block, EN-GJS-400-15U for the ...cylinder head and EN-GJL-200 for the liner. Tensile tests were carried out to obtain the ultimate tensile strength (UTS) of each material. The results for the UTS were: 460 MPa for EN-GJS-500-7U, 390 MPa for EN-GJS-400-15U and 170 MPa for EN-GJL-200. Likewise, Brinell-hardness measurements were carried out and the elements present in the materials were determined with spectrometry. Finally, the size of graphite particles in each sample was determined.
PDF
