Southwest Wisconsin Technical College

About: Southwest Wisconsin Technical College is a education organization based out in Fennimore, Wisconsin, United States. It is known for research contribution in the topics: Microstructure & Alloy. The organization has 240 authors who have published 219 publications receiving 2667 citations. The organization is also known as: Southwest Tech.

Formability and interface structure of Al/Mg/Al composite sheet rolled by hard-plate rolling (HPR)

Abstract: How to improve the bonding ability and quality performance of heterogeneous plates has always been one of the difficult problems in the field of high-performance heterogeneous composite sheet forming and manufacturing. In this paper, a new manufacturing method of heterogeneous clad plate, hard plate rolling clad plate, is proposed. The hot rolling process of Al/Mg/Al composite slab with or without hard plate was studied. The results show that the shear stress in the rolling direction (RD) can be transformed into the compressive stress in the normal direction (ND), and then the welding pressure between different composite layers can be increased. This method can suppress the bending and edge crack defects and significantly improve the shape quality and forming ability. At the same time, through the study of the interface structure of the composite plate, it can be known that the metallurgical bonding can be achieved with a small reduction after adding the hard plate. Two clear layers of Al3Mg2 and Al17Mg12 intermetallic compounds appear at the Al/Mg interface. The thickness of the diffusion layer is significantly larger than that of the traditional hot-rolled clad plate, and the thickness of the diffusion layer can reach 38 μm when the reduction is 60%. The yield strength is 172.3 MPa and the elongation is 21.5%. To sum up, the hot rolling of hard-plate provides a new idea for the forming and manufacturing of high performance heterogeneous composite plate.

Influence of Annealing Treatments on Microstructure and Mechanical Properties of an Extruded Mg AZ31/Al 7050 Laminate

Abstract: Mg AZ31/Al 7050 laminate was fabricated by co-extrusion directly from the as-cast Mg AZ31 and Al 7050 billets. The influence of annealing temperature and annealing time on microstructure and mechanical behavior of the extruded Mg/Al laminate was systematically studied. Results show that annealing treatments at 250 °C for 3 h or at 350 °C for 3 h do not result in an obvious grain coarsening of Mg layer and cannot remove the heterogeneous structure. Annealing does not vary texture in the Mg layer, a large fraction of //ND and a small fraction of //TD, but the intensity of component //ND weakens to some extent. Lamellar microstructure in the Al layer remains after annealing at 250 °C for 3 h or at 350 °C for 3 h. High fractions of the texture components S and cube exist in the extruded sample, and annealing treatment hardly changes their fractions. Post-annealing treatment will largely reduce yield strength of extruded plate and increase plasticity slightly. The yield strength drops from 302 MPa to 206 MPa after annealing at 250 °C for 3 h and to 141 MPa after annealing at 350 °C for 3 h. The elongation to fracture increases from 1.5% to 5.4% after annealing at 250 °C for 3 h and to 4.8% at 350 °C for 3 h. The corresponding mechanism was discussed.

Evaluation of hybrid power system alternatives: a case study

Abstract: Pursuant to executive and statutory policies, the National Park Service (NPS) has been evaluating the use of photovoltaic (PV) hybrid power systems for many of its remote, off-grid areas. This paper reports the results of a detailed technical and economic evaluation for one such area: the Needles District of Canyonlands National Park. The study evaluates the present power system and five alternative power generation configurations, four of which utilize PV. Projections are provided for the generator run-time and fuel use associated with each configuration as well as all initial and future costs. Included in the study are specific recommendations for energy efficiency improvements at the site. Results show that the generation system presently in use, two full-time diesel generators, has the lowest conventional20-year life cycle cost (LCC) of the six systems evaluated. However, when emissions costs are included (per NPS guidelines), several of the PV hybrid alternatives attain a lower LCC than the diesel-only system. General discussion of the effects of initial versus future costs for PV hybrids as they compare with engine generator systems is presented. Copyright © 1999 John Wiley & Sons, Ltd.

Fracture mechanism of an Al/AlN/CrAlN gradient coating on nitrogen implanted magnesium alloy

Abstract: The fracture behavior of an Al/AlN/CrAlN gradient coating on nitrogen implanted magnesium alloy was investigated using in-situ compression in a transmission electron microscopy (TEM) and finite element analysis. Results showed that the ductile Al layer was subjected to the highest interfacial stress due to the significant difference between the mechanical properties of Al and AlN. The high interfacial stress induced severe plastic deformation that led to fracture failure in the Al layer near the Al/AlN interface. The experimental results provide clue for the structural design of gradient coatings.