Determination of plastic deformation rate after solid particle erosion in ductile materials

AA6082-T6 aluminium alloy is a candidate material, specifically in aviation applications, which could be exposed to solid particle erosion. Solid particle erosion occurs due to repetitive high-speed impact of erodent particles on a target material. Every individual impingement of the erodent particle results in elastic/plastic deformations and material removal from the target material. In this study, solid particle erosion investigations were carried out under 1.5 and 3 bar with 60 and 120 mesh alumina particles. Both erosion rates and worn volumes of the samples were calculated and measured. Also, the authors present the plastic deformation rate in this study as a proportion of the actual (measured) worn volume to the equivalent volume of the mass loss. In addition, the average surface roughness of the samples were investigated, which is another parameter for understanding the effect of plastic deformation on surface properties during particle erosion.

Study on the Fatigue Failure Law of Gas Storage Caprock Under Periodic Injection and Production

Whether qualitative or quantitative, whether macroscopic or microscopic, Predecessors' research on the sealing ability of caprocks is concentrated on the static model of the caprock. A few scholars have also proposed the sealability evaluations of the caprock dynamic evolution process, they are all aimed at the dynamic evolution of geological historical periods, and there are few studies on the sealability of gas storage caprocks under periodic injection and production. In this paper, the characteristics of stress and strain under alternating loads of rock and non-rock materials are investigated and experimentally studied to clarify the law of fatigue failure of gas storage caprocks under periodic injection-production. The results show that it is possible that the microcracks may develop and propagate in the rock after the gas storage has experienced many periodic injections and productions, when the stress is far less than the rock strength limit, And then a macroscopic deformation is formed. The accumulated plastic deformation of the rock will increase, and the plastic deformation rate will gradually decrease, as the number of injection and production increases.

Asymmetric accumulative roll bonding of aluminum/copper composite sheets

For the first time in this study, a comprehensive experimental investigation was performed to investigate the effect of different roller diameter ratios ( Rd) on mechanical properties and plastic instability of Al/Cu composite produced by the asymmetric accumulative roll bonding process. For this purpose, Al/Cu composites were produced using three different Rd in three passes. Then, bond strength, mechanical properties, microstructure, and fracture surface of all specimens were determined. The results showed that due to the mechanisms underlying the severe plastic deformation processes, all composites’ mechanical properties sharply increased compared to aluminum and copper. As the Rd increases, the bond strength and hardness of the Al/Cu interface increase due to improved plastic deformation rate, surface expansion, and more extrusion of the material at the boundary of two layers. Besides, the hardness along the thickness was found to be very heterogeneous due to the uneven distribution of strain and strain hardening. Scanning Electron Microscopy (SEM) micrographs depicted a decrease in the layers’ thickness, an increase in the plastic instability of the copper, and improved bonding strength of the layers as Rd rises. However, in all specimens, the layered structure was maintained. Fracture micrographs also revealed that the fracture mechanism is ductile for both aluminum and copper layers at different Rd. However, with increasing the Rd, the number and the depth of the dimples along with micro-pores decrease. Finally, the non-uniform strain distribution of the process caused the micro-dimples to be drawn in different directions.

Classification of pressure welding methods depending on thermal deformation conditions

In this study, a classification of welding methods is proposed, based on the peculiarities of metal gripping under various heat-deformation conditions for the implementation of welding processes. The theoretical basis of the developed classification is the hypothesis of the critical sizes of active centers. The main approaches to the classification of welding methods are considered, and four groups of pressure welding methods are proposed, depending on the mechanism of formation of stable centres of gripping: mechanical welding methods with low plastic deformation rate; mechanical methods of welding with a high plastic deformation rate; thermo-mechanical welding methods, in which, in addition to heating by deformation, additional sources of thermal energy are used to increase the temperature in the zone of joint formation; thermal pressure welding methods that envisage only a thermal activation channel.

Effect of Cyclic Load Amplitude on the Evolving Characteristics of Accumulative Deformation in Subgrade Bed

To investigate the evolving characteristics of plastic deformation for the angular gravels that are used to construct subgrade bed, a laboratory model test is performed with cyclic load applying. Vertical deformation is measured in real time by displacement transducers and further modified to analyze the plastic behavior of model fillings. It can be found that vertical plastic deformation shows quite different developing patterns under the effect of different cyclic amplitudes for a given model. A power function is adopted to describe the relationship between deformation rate and loading times. By analyzing the value of the power exponent and the corresponding developing features of plastic deformation rate, model filling status can be classified into four different zones, i.e., rapid stabilization, tardy stabilization, tardy failure, and rapid failure. Such a classification reveals different developing patterns of plastic deformation and satisfies the design of subgrade bed for ballasted and unballasted railway.

Effect of plastic deformation rate at room temperature on structure and mechanical properties of high-Mn austenitic Mn-Al-Si 25-3-3 type steel

Purpose: The aim of the paper is to determine influence of plastic deformation rate at room temperature on structure and mechanical properties of high-Mn austenitic Mn-Al-Si 25-3-3 type steel tested at room temperature. Design/methodology/approach: Mechanical properties of tested steel was determined using Zwick Z100 static testing machine for testing with the deformation speed equal 0.008 s-1, and RSO rotary hammer for testing with deformation speeds of 250, 500 and 1000s-1. The microstructure evolution samples tested in static and dynamic conditions was determined in metallographic investigations using light microscopy as well as X-ray diffraction. Findings: Based on X-ray phase analysis results, together with observation using metallographic microscope, it was concluded, that the investigated high-Mn X13MnAlSiNbTi25-3-3 steel demonstrates austenitic structure with numerous mechanical twins, what agrees with TWIP effect. It was demonstrated, that raise of plastic deformation rate produces higher tensile strength UTS and higher conventional yield point YS0.2. The UTS strength values for deformation rate 250, 500 and 1000 s-1 grew by: 35, 24 and 31%, appropriately, whereas in case of YS0.2 these were: 7, 74 and 130%, accordingly, in respect to the results for the investigated steel deformed under static conditions, where UTS and YS0.2 values are 1050 MPa and 700 MPa. Opposite tendency was observed for experimentally measured uniform and total relative elongation. Homogeneous austenitic structure was confirmed by X-ray diffractometer tests. Research limitations/implications: To fully describe influence of strain rates on structure and mechanical properties, further investigations specially with using transmission electron microscope are required. Practical implications: Knowledge about obtained microstructures and mechanical properties results of tested X13MnAlSiNbTi25-3-3 steel under static and dynamic conditions can be useful for the appropriate use of this type of engineering material in machines and equipment susceptible to static or dynamic loads. Originality/value: The influence of plastic deformation at room temperature under static and dynamic conditions of new-developed high-manganese austenitic X13MnAlSiNbTi25-3-3 steels were investigated.

Influence of Aging Treatments on the Structural and Mechanical Properties of AGS Alloy Wire Cold Drawn

The scope of this work is to study of microstructural changes and mechanical properties during natural and artificial ageing treatment of AGS Alloy wire cold drawn with different deformation at ENICAB in Biskra. And as well to know the phase formation during different deformation of aluminum alloys wires. as well as the combined influence of the plastic deformation rate and the aging temperature. Wire section reduction shows a change in microstructure and texture. The methods of characterization used in this work are: scanning electron microscope and X-ray diffraction, micro hardness (Hv).

Analysis of Rheological Behavior on Transformation Induced Plasticity Steel

The cupping tests under different rate demonstrated that there was a correlation between the plastic deformation and shaping time of transformation induced plasticity (TRIP) steel, illustrating that there was also the rheology in the process of plastic forming for solid metal materials. The creep experiments were carried out by Gleeble 3500 thermal simulated test machine, and Mises yield rule was used to verify the creep experiments satisfying the visco-plastic conditions when the load was greater than yield strength. The visco-plastic deformation rate of creep experiments was obtained based on Bingham model. The viscous correlation coefficient (γ) was deduced, reaching that the viscosity of TRIP steel shows deformation resistance in the process of plastic shaping. These results provide the theoretical basis for increasing the plate yield and controlling the forming rate.