Search

In the present study, a combination of cold rolling and subsequent annealing was used to produce an AISI 304L stainless steel with different grain sizes (650 nm, 3 μm and 12 μm). Wear behavior of the steel was subsequently examined using dry sliding wear test under different loads of 10 N, 20 N and 30 N. Different microstructural characterizations were conducted on the samples. The results demonstrated that the ultra-fine grained steel (650 nm grain size) had better wear resistance under normal loads of 10 N and 20 N, whereas under the normal load of 30 N, it showed weak wear resistance as compared to the steel with larger grain size (3 μm and 12 μm). This behavior can be attributed to the amount of induced martensitic transformation formed during the wear test. This transformation was evaluated using XRD analysis and quantified by Ferritescope measurements. Wear mechanism was recognized as delamination in the early stages of the wear test and the mixture of delamination and abrasion for higher distances.

In this study, an aluminium–zinc composite was produced for the first time by using a continual annealing and roll-bonding (CAR) process. A composite with homogeneous distribution of fragmented zinc layers in aluminium matrix was produced after ten CAR cycles. The results demonstrate that tensile strength of the final composites increases up to 410 MPa, which is about 4 times higher than those of initial aluminium and zinc sheets. However, elongation of the composite reduced down to 4% after ten CAR cycles. The fracture surfaces of the tensile samples were observed by scanning electron microscope (SEM) to evaluate the failure mode. Observations reveal that the failure mode in CAR-processed composites is a typical ductile fracture which shows deep dimples in samples with few CAR cycles, while the failure mode was shear ductile fracture with shallow and elongated dimples in samples with ten CAR cycles.

In this study, Al–Zn composite was produced for the first time by using of Al 1050 and commercial Zn alloy sheets through accumulative roll bonding (ARB) process at ambient temperature. In this process after sandwich preparation, in per cycle applied 50% reduction in thickness. It was observed that by increasing ARB cycles, thickness of individual Al and Zn sheets decreased; finally, zinc layers were necked, fractured and dispersed in the aluminum matrix. After ten ARB passes, an Al–Zn composite with homogeneously distribution of fragmented zinc layers with thickness of less than 3 μm in aluminum matrix was produced. Structure and mechanical properties of this composite were evaluated at different cycles of ARB process. During ARB cycles, it was observed that with increase of number of ARB cycles, the strength and microhardness increased while elongation at the first cycles increased and then decreased.

Vegetation on river banks and bed roughness are important factors affecting flow structure, sediment transport, erosion and geomorphology in rivers. In this experimental study, the impacts of vegetation on flume walls, grain size of bed gravels and aspect ratio on characteristics of shear stress distribution, Coles' wake parameter, the kinematic energy correction factor (α) and the momentum correction factor (β) have been assessed. Reynolds stress distribution illustrates a three-layer pattern when the aspect ratio is smaller than 2. In addition, the aspect ratio and changes of vegetation affect α, β as well as the Coles' wake parameter Π.