The Effects of Different Gaps on the Weld Morphology, Microstructure and Residual Stress of AH36 Steel were Studied by Laser Arc Hybrid Welding

In this study, laser (TruDisk16002)-arc (MAG) hybrid welding was used to weld a 5mm thick sheet of AH36 steel with a gap of 0mm and 1mm. The results show that when the current of MAG is 205A, the voltage is 31.9V, and the laser power is 7.5KW, the welds of 0mm gap and 1mm gap are well formed, showing a typical nail shape, and the 0mm gap weld is better than 1mm. Under the same welding process parameters, the heat-affected zone of a 0mm gap weld is less than 1mm. Upper bainite is found in the 1mm weld gap structure. In the two gap cases, the residual stress on the lower surface is larger than that on the upper surface, and the residual stress in the 1mm weld gap is larger. The weldability of 0mm weld gap is better than 1mm.

Estimating the parameters of simple models from two-component on-time airborne electromagnetic data

The horizontal and vertical components of the on-time electromagnetic (EM) response can be used to estimate the parameters of simple models like thin sheets, half-spaces, thin sheets over a lower half-space and a two-layer model. The formulae used in these methods are valid in areas where the on-time response is essentially proportional to the conductivity or conductance, the so called "resistive limit". The half-space and thin-sheet over a lower half-space models can be combined to give an estimate of the conductivity for a lower half-space below a thick sheet that might be reasonable for the whole of the survey area. With this estimation an equation solver can be used to estimate the thickness and conductivity of the overlying thick sheet over the whole survey area. This latter approach seemed most appropriate for the Russell South area in the Athabasca Basin, Canada, where GEOTEM data has been collected. The output of the algorithm was generally stable. Although it did not always reliably reproduce the overburden thicknesses as measured in a set of reference drill holes, it did give an estimate that was reasonable in the relatively conductive areas.

Abstract P377: Collagen Remodeling Of Spontaneously Hypertensive Rats Undergoing Quinapril Treatment Measured By Three Dimensional Shape Analysis

Introduction: Myocardial collagen structure is a complex three dimensional (3D) hierarchy, organizing cardiomyocytes and providing structural integrity. Changes in collagen organization have a crucial role in cardiac remodeling. However, quantitative methods for the analysis of collagen structures are still lacking. Herein, we apply our collagen shape analysis framework to compare within-sheetlet collagen (both endomysial collagen surrounding myocytes and perimysial cords) against sheetlet-surface collagen (perimysial meshwork collagen deposited between sheetlets) in spontaneously hypertensive rats undergoing quinapril treatment. Hypothesis: The different functional properties of endomysial and perimysial meshwork collagen are linked to their structure and will have markedly different features quantifiable by 3D shape analysis. Methods: Rat myocardium was stained for collagen (picrosirius red), and the left ventricular free wall imaged using extended volume confocal microscopy (0.4 μm 3 voxel size). The 3D image volumes were segmented into within-sheetlet and sheetlet-surface regions. Shape analysis was performed using eigenanalysis of the inertia matrix to derive 3D morphological (elongation and flatness) parameters, characterizing the collagen shape in the two regions. Results: Shape analysis revealed marked differences between within-sheetlet and sheetlet-surface collagen organization. Long-term quinapril treatment resulted in notable differences in within-sheetlet collagen shape in rats at 14 months of age (mo) compared with 24 mo. At 14 mo, the within-sheetlet collagen is a mix of sheet-, ribbon-, and rod-like structures (elongation: 0.43, flatness: 0.05), but by 24 mo this has remodeled to predominately thin rod-like structures (elongation: 0.03, flatness: 0.35). The sheetlet-surface collagen consisted of thick sheet-like structures in both 14 and 24 mo rats (elongation: 0.83 vs 0.79, flatness: 0.13 vs 0.09). Conclusion: Shape analysis in 3D showed marked differences between within-sheetlet and sheetlet-surface collagen structure, as well as differences between early treatment and late treatment of diseased hearts.

Microstructure and Mechanical Properties of Al-Mg-Si Similar Alloy Laminates Produced by Accumulative Roll Bonding

As the applications of heterogeneous materials expand, aluminum laminates of similar materials have attracted much attention due to their greater bonding strength and easier recycling. In this work, an alloy design strategy was developed based on accumulative roll bonding (ARB) to produce laminates from similar materials. Twin roll casting (TRC) sheets of the same composition but different cooling rates were used as the starting materials, and they were roll bonded up to three cycles at varying temperatures. EBSD showed that the two TRC sheets deformed in distinct ways during ARB processes at 300°C. Major recrystallizations were significant after the first cycle on the thin sheet and after the third cycle on the thick sheet. The sheets were subject to subsequent aging for better mechanical properties. TEM observations showed that the size and distribution of nano-precipitations were different between the two sheet sides. These nano-precipitations were found to significantly promote precipitation strengthening, and such a promotive effect was referred to as hetero-deformation induced (HDI) strengthening. Our work provides a new promising method to prepare laminated heterogeneous materials with similar alloy TRC sheets.

A Novel Test Design for Large Strain Uniaxial Reverse Loading of AZ31B Sheet Out of the Rolling Plane

Understanding a magnesium alloy sheet's response to load reversals is important to accurately simulate and optimize a component's manufacturing process. Through this research, the room temperature compression-tension and tension-compression experiments with strains up to ∼12% are performed on AZ31B-H24 sheet specimens along the normal direction of a 6.35 mm-thick sheet. Miniature specimens machined through thickness are tested using a novel setup designed for large strain reverse loading data generation where specimen size is limited. The reliability of the devised setup is verified by finite element simulation and by reproducing in-plane curves obtained via an anti-buckling fixture. A shot peening process involving prevailing through-thickness deformation is modeled and numerical results indicate that employing only in-plane properties of magnesium sheets for simulating such processes can lead to inaccurate predictions.

Investigation of Temperature-Time Modes of Rolling of Thick-Sheet Steel and Mechanical Properties of Finished Products

The article is devoted to the study of technological modes of hot rolling of tube steel on a thick-sheet mill and mechanical properties of the finished products. Five slabs were rolled under the experimental regime in accordance with the study plan. The temperature conditions of rolling at the final stage of deformation and the modes of accelerated cooling of rolled products were changed. Dependencies between technological parameters and mechanical properties allowed developing recommendations on improvement of technology of rolling and of the subsequent accelerated cooling of metal.

Influence of clinching steps and sheet thickness on the mechanical properties of the clinching joint

In order to reduce the protrusion height and increase the strength of the clinched joint, a two-step clinching method was investigated in the present study. The whole process contains two steps. The first step is used to produce one-step clinched joints, and the second step is used to press the one-step clinched joints to reduce the protrusion height and increase the joining strength. The influences of clinching steps and sheet thicknesses on the mechanical properties of the clinched joint were investigated. The main failure mode of all the clinched joints in the strength tests is the neck fracture mode. The neck thickness can be enlarged by the two-step clinching method, and the protrusion height can be reduced. TCJ2.5-2.0 joint has the highest energy absorption and strength, and OCJ2.0-2.5 joint has the lowest energy absorption and strength. The two-step clinching process can contribute to increasing energy absorption and joining strength. For getting higher strength, the thick sheet should be taken as the top sheet. With higher strength and lower protrusion, the use of two-step clinched joint will be convenient in the mechanical engineering areas.

Influence of Welding Parameters and Filler Material on the Mechanical Properties of HSLA Steel S960MC Welded Joints

This article provides an overview of the influence of welding parameters and filler material on changes in the heat-affected zone (HAZ) of thermo-mechanically controlled processed (TMCP) steel welded joints. The research focused on evaluating the effect of heat input and cooling rate on the width of the soft zone, which significantly affects the mechanical properties of welded joints. The negative effect of the soft zone is more pronounced as the thickness of the material decreases. Therefore, the object of this research was a 3-mm-thick sheet of S960MC steel welded by gas metal arc welding (GMAW) and metal-cored arc welding (MCAW) technology. Variable welding parameters were reflected in different heat input and cooling rate values, which led to a change in the properties of the HAZ and thus the mechanical properties of the welded joints. The changes in the HAZ were analyzed by microscopic analysis and mechanical testing. The measured results showed a significant effect of heat input on the cooling rate, which considerably affected the width of the soft zone in the HAZ and thus the overall mechanical properties of the welded joints.