Influence of cold-rolling reduction on retained austenite texture in cold-rolled and intercritically annealed TRIP-assisted steel

The newly developed multiphase transformation-induced plasticity (TRIP) steels are of interest for industrial applications because of their excellent combination of high strength and ductility. Their performance can be successfully controlled by designing an optimum balance in the volume fractions of ferrite, bainite and retained austenite. The characteristics of the retained austenite are considered to be the main key to achieving the desired final properties. Against this background, the effects of retained austenite characteristics, such as volume fraction, carbon concentration, size and shape, on the behaviour of TRIP steels have been studied. The crystallographic orientation of the retained austenite was measured by electron backscattered diffraction (EBSD). The effect of initial cold-rolling reduction on the microtexture development of the retained austenite was studied on an aluminium-containing TRIP steel. The results show that, by increasing the cold-rolling reduction before the final austempering, the main components of the face-centred cubic phase, i.e. copper, brass and Goss, dominate the texture of the retained austenite. In contrast, the copper and Goss components of the retained austenite are absent in the texture of lightly deformed sheets. The features of the preferred orientation of the retained austenite are discussed and explained in terms of the annealing texture of the recrystallized ferrite and bainite

CFD Simulation of CO2 Sorption in a Circulating Fluidized Bed Using Deactivation Kinetic Model

The Computational Fluid Dynamics (CFD) approach was used to simulate sorption of CO2 using solid sorbents in the riser section of a circulating fluidized bed. The simulation results were compared with the experimental data of Korea Institute for Energy Research (KIER) for continuous CO2 sorption using potassium carbonate in a circulating fluidized bed system

Deformation behavior and processing map of ATI 425 with initial lamellar microstructure

The effect of hot compression temperatures and strain rates on deformation behavior and resultant microstructure of ATI 425 alloy with initial lamellar microstructure was investigated in this study. The temperature and strain rate of the hot compression test were chosen to be in the 700-1100 °C and 0.001-1 s-1 ranges, respectively. The stress-strain curve and microstructure evaluation show that the alloy's flow softening is associated with globularization and dynamic recrystallization mechanisms. The constitutive equation calculates the activation energy for the α/β and β regions to be 348 kJ/mol and 201 kJ/mol, respectively. Dynamic recovery and partial recrystallization are the dominant structure modification mechanisms in the beta single-phase region. Bending and fragmentation of alpha plates is the dominant mechanism of microstructure promotion in the α/β region at low temperatures and low strain rates, less than 0.1s-1. Local shear and alpha plate break-up are the main factors in structural modification at high strain rates, greater than 0.1s-1. The extracted process map at 0.5 strain revealed three zones: instability, safe zone, and peak zone, with power dissipation efficiencies of 0 -0.25%, 30-40%, and above 40%

Experimental and numerical evaluation of diesel-hydrogen dual-fuel combustion in a HD single cylinder engine

Climate changes emerging in the last few decades have resulted in accelerated efforts to guarantee a viable global ecosystem. Despite the aim of low-carbon economies to integrate all aspects for the minimal GHG outputs, the transport sector is under severe obligation to abide due to the related substantial contribution of CO2 emissions. Although, in the last few years the electrification of powertrain systems has gained significant attention in the media, it is widely acknowledged by the industry that the internal combustion engine will remain a dominant source of propulsion for decades to come. In recent years, conventional fossil fuels (gasoline and diesel) have been partially replaced with the alternative fuels such as biodiesel, natural gas, ethanol, hydrogen, etc. These substitutions were beneficial in diverse perspectives making significant reductions in exhaust pollutants with maintained performance. The currently reported work was concerned with experimental and numerical evaluation of the potential to partially replace diesel with hydrogen fuel, which continues to attract attention as a potential longer term alternative fuel solution, whether produced on-board or remotely via sustainable methods. The test engine adopted was of a single cylinder HD diesel with typical common rail diesel fuel injection and EGR of a production HGV’s engine. The experimental work was involved with the fumigation of hydrogen and intake air enrichment with oxygen at two particular engine loads (6 and 12 bar net indicated mean effective pressure -IMEPn-) typically visited under real world HGV driving conditions. Highest practical hydrogen substitution ratios could increase indicated efficiency by up to 4.6% and 2.4% while reducing CO2 emissions by 58% and 32% at 6 and 12 bar IMEPn respectively. Soot and CO emissions were reduced as more hydrogen was supplied, particularly at 6bar IMEP. Furthermore, intake air enrichment with oxygen resulted in a faster combustion process. This could restraint soot and minimised CO emissions at the expense of considerably higher NOx emissions. The numerical study was made using the commercial engine simulation package, GT-Power. Initially a reverse-run calculation known as Three Pressure Analysis (TPA) was applied for determining the cylinder trapped conditions in addition to the measured burn rate. Two distinct phenomenological models were used in parallel with aim of modelling the dual-fuel combustion. By comparing the optimised calibration factors in different operating points, in-depth evaluation of the unique dual-fuel combustion phenomenon was possible, including evaluation of burning velocities and the knock-on effects on performance under varied mixture compositions. It was concluded that hydrogen substitution provides a viable method of displacing diesel and the associated carbon emissions with favourable accompanying reductions in soot. The phenomenological “DualFuel” model performed well under ‘conventional’ dual-fuel conditions but was less reliable when a proportion of the diesel was premixed. The arising error was largely associated with lack of dual-fuel burning velocity data, which will remain a key barrier to dual-fuel simulation as the premixing is largely acknowledged to improve the combustion efficiency

Efficient Static Analysis of Assemblies of Beam-Columns Subjected to Continuous Loadings Available as Digitized Records

Beams, beam-columns, columns, and frames, are of major importance in structural engineering, and especially buildings and infrastructures analysis and design. In some cases, these structural members are subjected to static loadings, that though are continuous with respect to the longitudinal axes, are available as digitized records. Finite element analysis of assemblies of these members may be computationally expensive when the loading is digitized densely. In order to reduce this computational effort, attention is paid to a technique originally proposed in 2008 for reduction of the computational effort in time integration analysis. In view of the convergence-based nature of this technique, in this paper, the technique is adapted to static analysis of assemblies of beam-columns subjected to digitized loadings. The good performance of the adapted technique is demonstrated from different points of view, and is compared with the performance of the technique in time integration analysis

Manufacturing of the aluminum metal-matrix composite reinforced with micro- and nanoparticles of TiO₂ through accumulative roll bonding process (ARB)

ABSTRACT: The aluminum metal-matrix composites reinforced with the micro- and nanoparticles of TiO₂ were manufactured in the form of sheets through the accumulative roll bonding (ARB) process which has been lately considered as a novel method under an intense plastic deformation so as to produce particulate-reinforced metal-matrix composites. The microstructural examinations via optic microscopy and scanning electron microscopy (SEM) depict that the distribution of TiO₂ particles in the aluminum matrix is almost uniform and also the dispersion of the microparticles of TiO₂ is more homogeneous than that of the nanoparticles one. Furthermore, the tensile tests demonstrate the noteworthy enhancements in the tensile strengths of the composites, compared to the Al 1100 as the virgin metal, however, by attenuating the size of the particles, i.e. from micron to nano, the composite tensile strengths are augmented. The fractographic analysis of the fracture surfaces revealed that the fracture mode in the ARB-processed Al/TiO₂ composite is the shear ductile rupture type

Mutant Allele of CD44 (rs8193C>T) and Pum2 Regulatory Element as A Prognosis Factor of Prostate Neoplasms: A Case-Control and In Silico Studies

ObjectiveExpression of CD44 variant 6 (CD44v6) as a homing-associated cell adhesion molecule (HCAM), hasproved to change most cancer cells. Aim of the study is the effect of mutant allele of CD44 (rs8193C>T) and Pum2regulatory element as a prognosis factor of prostate neoplasms: a case-control and in silico studies in the Mazandaranprovince-Iran.Materials and MethodsIn a case-control study, CD44-rs8193C>T genotyping of the 420 prostate neoplasms (210benign prostatic hyperplasia (BPH) patients and 210 prostate cancer patients) and 150 healthy samples are performedby the touchdown polymerase chain reaction with confronting two-pair primers (PCR-CTPP) method. The T mutantallele effects on the mRNA structure and cell pathways were also investigated in silico methods.ResultsOur results showed that the increase of T mutant allele frequency was significantly associated with BPHcompared with prostate cancer. Furthermore, results showed TT genotype was significantly associated with BPH[odds ratio (OR)=0.572 and P=0.015], and also influenced the CD44v6 transcript secondary structure, miRNA binding,and regulatory element-binding site for Pum2 protein. Attachment of Pum2 to standard CD44 transcript may lead totranscript isoform-switching and shift-expression to a variety of CD44 isoforms, which can trigger some of the cellsignaling pathways, such as Nanog-Stat, PKC-Nanog, and PKC-Twist.ConclusionBased on this, the presence of the T mutant allele of CD44 (rs8193C>T) in the populations may createa regulatory element-binding site for Pum2. So, it could be known as a prognosis factor and prediction of prostateneoplasms. However, more comprehensive studies in different populations (with various ethnicities and large populationsizes), and also CD44v6 gene expression studies in protein and transcript levels are required to confirm our data