Microstructure and Mechanical Properties Change with Cold Rolling of New Ti-13Nb-1.5Ta-3Mo Alloy

In this paper, a new metastable Titanium alloy in the Ti-Nb-Ta-Mo system has been successfully produced using both the d-electron and Moeq concept. The influence of cold rolling on the microstructure and hardness was investigated. The alloy was fabricated by arc melting, cold rolled up to 90% reduction in thickness and characterized using X-ray diffraction (XRD), optical microscope and Vickers microhardness. The XRD peaks depicted both β and α′′ phases in all the cold rolled specimens. The hardness of the alloy increased with increasing cold rolling reduction thickness. An excellent plasticity (≥ 65%) and compressive strength up to (2.9 GPa) was achieved with low Young’s modulus (31 GPa) and no failure or crack on the alloy. Also, the alloy demonstrated a high compressive true strength coefficient (k ≈1426 MPa) along with improved strain hardening index (n ≈ 0.41). Based on the XRD, optical microscope and microhardness indentation micrographs, the deformation mechanism of Ti-13Nb-1.5Ta-3Mo was found to be a combination of stress induced transformation, mechanical twinning and slipping.

Investigation of the relationships between the alveograph parameters

Alveograph analysis is an established method for flour characterisation, and several alveograph parameters have been introduced over the years. Typically, ten parameters are found for every analysis from the air pressure curve in the modern versions of the alveograph, but the relationships between the parameters and their potential redundancy are not well described in the literature. In this work, an overview of the parameters is provided, including how they are found and what they may represent, and the integral relationship between the parameters was investigated using Pearson correlation analysis of the parameters from 532 pressure curves. The parameters G (swelling index), Dmax (maximum of first derivative), SH (strain hardening index) and K (strength coefficient) exhibited very strong correlations with other alveograph parameters (r > 0.97), and these parameters do therefore not provide additional information. The parameters P (maximum overpressure), L (abscissa at rupture), W (deformation energy), P/L (configuration ratio), Ie (elasticity index) and Dmin (minimum of first derivative) on the other hand, represent a relatively basic set of parameters that uniquely characterises various parts of the pressure curves and thus the dough rheology/physics during dough inflation. Nevertheless, even between this basic set of parameters relatively strong correlations were found, signifying that they are interrelated, as they all are affected by changes in the dough constituents.

The Self-Enforcing Starch–Gluten System—Strain–Dependent Effects of Yeast Metabolites on the Polymeric Matrix

The rheological behaviour of dough during the breadmaking process is strongly affected by the accumulation of yeast metabolites in the dough matrix. The impact of metabolites in yeasted dough-like concentrations on the rheology of dough has not been characterised yet for process-relevant deformation types and strain rates, nor has the effect of metabolites on strain hardening behaviour of dough been analysed. We used fundamental shear and elongational rheometry to study the impact of fermentation on the dough microstructure and functionality. Evaluating the influence of the main metabolites, the strongest impact was found for the presence of expanding gas cells due to the accumulation of the yeast metabolite CO2, which was shown to have a destabilising impact on the surrounding dough matrix. Throughout the fermentation process, the polymeric and entangled gluten microstructure was found to be degraded (−37.6% average vessel length, +37.5% end point rate). These microstructural changes were successfully linked to the changing rheological behaviour towards a highly mobile polymer system. An accelerated strain hardening behaviour (+32.5% SHI for yeasted dough) was promoted by the pre-extension of the gluten strands within the lamella around the gas cells. Further, a strain rate dependency was shown, as a lower strain hardening index was observed for slow extension processes. Fast extension seemed to influence the disruption of sterically interacting fragments, leading to entanglements and hindered extensibility.

Springback Analysis in Sheet Metal Forming Using Modified Ludwik Stress-Strain Relation

This paper deals with the springback analysis in sheet metal forming using modified Ludwik stress-strain relation. Using the deformation theory of plasticity, formulation of the problem and spring back ratio is derived using modified Ludwik stress strain relationship with Tresca and von Mises yielding criteraia. The results have been representing the effect of different value of or ratio, different values of Strain hardening index (), Poisson’s ratio (), and thickness on spring back ratio (). The main aim of this paper is to study the effects of the thickness, ratio, and Poisson’s ratio in spring back ratio.

Analysis of Microstructure and Textures on Batch Annealed IF Steel with Different Cold Reduction Ratio

Based on the experimental materials of hot rolled Ti+Nb-IF steels and Ti-IF steels produced in the industry, the effects of cold reduction ratios on its microstructures, mechanical properties and textures were investigated. The results show that experimental samples with different cold reduction ratios have been finished recrystallization by batch annealing at 720°C and soaking with 5h. As the cold reduction ratio increases, the grains will be refined and uniform, and the textures trends to be {111} texture. The {223}<110>, {111}, and {114}<110> textures appeared after cold rolling are inherited followed by annealing, whose intensities would be higher as the cold rolling ratio increased. And the textures will transform to the {223}<110>, {111}<110> and {114}<110> textures. With the increasing cold reduction ratio, the values of the yield strength Rp0.2 and tension strength Rm increase, but the Rp0.2 is almost about 100MPa. However, the strain hardening index n90 gradually decreases. The plastic strain ratio r90 which reaches the maximum with cold reduction ratio of 70% increases firstly and then decreases. Thus, the optimal cold reduction ratio of 70% to 80% is determined, which can obtain good deep drawing performances.

Examination of the Strength and Ductility of AA-1050 Material Shaped with the MUlti-Stage Deep Drawing Method

Examination of the Strength and Ductility of AA-1050 Material Shaped with the MUlti-Stage Deep Drawing Method Deep drawing materials are easily shapeable materials, because of their high ductility. Aluminum alloy materials are classified in the deep drawing materials group because they are easily shapeable. In order to increase the strength, materials are made an alloy by adding some chemical additives. They are also provided strength increasing by tempering. Normally, materials harden when reshaped under plastic deformation. Reshape the shaped materials harden while reducing its ductility. In this study, changes in mechanical properties immediately after the AA-1050 (T0) sheet material is shaped by the multi-stage deep drawing method and after storage were investigated. It was calculated that a 4-stage shaping is needed for a tube production at selected sizes. Deep drawing treatments are made in sizes of these stages. Samples were collected from each cold-shaped intermediary form. Mechanical properties of this materials are determined by applying tensile test. Some basic parameters, like tensile stresses, max. uniform strain rates, strain hardenings and strength coefficients, are investigated and compared. Obtained data were explained using graphs. It was observed that tensile strength increased and strain quantities were reduced at every stage. It is also seen an increase in strain hardening index.

Effects of Annealing Treatment on Texture and Stamping Properties of AZ31 Magnesium Alloy

The microstructure, texture and basic stamping properties of AZ31 magnesium sheet are studied in this paper with optical microscopy (OM), scan electron microscopy (SEM), X-ray diffraction (XRD) and MTS universal tester. The results show that the basal texture (0002) is enhanced and the grain size decreases as the thickness of sheet decreases. However the texture depresses in the 0.52mm sheet due to the complete recrystallization under deep rolling reduction. The strength and elongation decreases and the strain hardening index (n value) increases as the thickness increases. The precipitation decreases and the basal texture depresses after annealing treatment. The peak value ratio of crystal plane (0002) of 1.3mm sheet reduces from 67% to 53% when annealing treated at 300°C for 2h. In addition, the strain hardening index (n) value reduces from 0.2535 to 0.2053 and the anisotropic index (r) value increases from 1.966 to 2.108 when the sheet is treated at the same condition.

Sensitivity Analysis on Effect of Parent Materials Parameter on Formability of Tailor Welded Blank

The parent sheet selection in TWB designing is largely dependant on the effect of parent materials parameters on formability of TWBs. Experiments and FE simulations were performed to study the effect of material parameters of TWB’s parent sheets such as t (thickness ratio), k (strength factor of materials), n (strain hardening index), r (anisotropy index) on LDH and weld-line movement of TWB. Orthogonal experiments and range analysis were used to analyze the sensitivity on effect of different parameter on LDH and weld-line movement. The results show that LDH of TWB decreases with increasing ration of stronger sheets parameters to weaker ones, and the rate decreases gradually; in contrary, weld-line movement increases and the increasing rate decreases gradually. Furthermore, different parameters make various contributions to LDH and weld-line movement of TWBs and the effect degree of each parameter changes with different thickness ratios.