Shear Punch Test Research Articles

Work hardening under shear and tensile deformation modes

The flow and work hardening behaviour of pure copper (FCC), interstitial-free steel (BCC) and AZ31 magnesium (HCP) sheets were investigated under tensile and shear deformation modes. The sheets were deformed via tensile and shear punch testing (SPT) at room and 0.4Tm temperatures. The work hardening rate of sheet metals quantified by the Kocks–Mecking modelling approach was found to be significantly lower in the shear mode than in tension. Taylor factor values for the deformed samples were computed from the measured textures after tensile and shear tests to reveal the role of textural evolution on the work hardening rate. The difference in the work hardening under two strain paths was proposed to be associated with the lower Taylor factor values.

Effects of Sr additions on the microstructural stability and mechanical properties of a cast Mg–4Zn alloy

The effects of Sr additions (0.3, 0.6 and 0.9 wt%) on the microstructural evolution, thermal stability, and mechanical properties of a cast Mg–4Zn alloy were investigated. The extent of grain growth and stability of the intermetallic compounds were studied by optical and scanning electron microscopy (SEM), respectively. Mechanical properties of the studied alloys were evaluated by shear punch testing (SPT) method and also the hardness test. Hardness and shear strength of the base alloy were increased by Sr additions in the as-cast condition, due to the grain refinement effect of Sr and also presence of the Sr-containing Mg17Sr2 and Mg70Zn25Sr5 precipitates. However, the optimum amount of Sr was determined to be 0.3 wt%, above which no further improvement in the shear strength of the as-cast alloys was observed, due to the coarsening of the precipitates. The obtained microstructural results indicated that while both of the base and Sr-containing alloys have appropriate thermal stability at 330 °C, the grain size of the base alloy increased significantly and also the Mg4Zn7 particles were dissolved in the matrix after annealing treatment at 400 °C for 96 h, resulting in considerable decrease in the shear strength. However, grain growth was trivial in the Sr-containing alloys, due to the presence of thermally stable Mg17Sr2 particles. Accordingly, the Sr addition was found to be beneficial to improve the stability of the microstructure and mechanical properties of the Mg–4Zn alloy.

Derivation of material properties using small punch and shear punch test methods

The Small Punch (SP) and Shear Punch (ShP) tests are well established mechanical test approaches that have found application in several industrial sectors for material ranking and mechanical property estimation, particularly where more conventional approaches are inhibited. Despite the advantages that the two test methodologies have to offer, the main drawback is the complex understanding of the mechanical data generated from the experiments and how it can be correlated to more recognised properties. Typically, the most desired properties relate to the uniaxial properties of yield stress, ultimate tensile strength and ductility, but to date, there is no single robust and overarching approach for correlating such properties for a wide array of metallic materials that exhibit varying levels of ductility. This paper will for the first time directly compare properties obtained from a series of uniaxial tensile, SP and ShP tests across several metallic materials, and look to establish and correlate equivalent properties across the different test types. The materials investigated range from commercially pure entities to more advanced alloy systems. The generated results, empirical relationships and numerical simulations will inform which materials can be correlated across the different test regimes, and identify why the relationship in certain materials breaks down.

Investigation on the microstructure and mechanical properties of Ti6Al4V titanium alloy electron beam welding joint

Electron beam welding (EBW) is a fusion joining process particularly suitable for welding titanium plates. In the present work, 2.5 mm thickness Ti6Al4V titanium alloy plates were butt-welded together with backing plates by EBW. The detailed procedures of experiments were used to investigate the microstructure and mechanical properties of welded joints. The optimum welding speed was determined by microstructure examinations, microhardness tests, X-Ray diffraction tests, shear punch tests (SPT) and stress simulation calculations. The results showed that all microstructure of welded metal (WM) was martensite phase under the different welding speeds. In the heat-affected zone (HAZ), the martensite phase gradually evolved to be small and equiaxed. It can be seen that the microstructure of each region in welded joints did not change significantly. When the welding speed is between 8 mm/s and 14 mm/s, it can be seen from the macroscopic appearance of the joints that there was no utterly fused penetration between the butt plate and substrate. Finite element simulation was carried out for the no-penetration depth under different welding conditions, and it was found that the stress suffered by the small no-penetration depth was the smallest. Using different welding parameters shows that the engineering stress in WM was higher than other areas, and BM was the lowest. As welding speed increases from 8 mm/s to 14 mm/s, the variation of microhardness distribution was not evident.

Tribological and mechanical properties of surface nanocomposite AlCoCrFeNi2.1 high-entropy alloy produced by FSP

In the present work, the nanocomposite AlCoCrFeNi2.1 high-entropy alloy was produced using friction stir processing (FSP) with the addition of TiO2 nanoparticles. The size and weight percent of added nanoparticles were 30 ± 5 nm and 3 wt%, respectively. The applied rotating and transvers speeds were 800 rpm and 50 mm/min, respectively. The microstructural evolutions, the hardness changes, the shear properties and the tribological behavior were evaluated after applying FSP. These studies were carried out using X-ray fluorescence (XRF), optical microscopy, scanning electron microscopy (SEM), energy dispersive X-Ray analysis (EDX), X-Ray diffraction (XRD), Rockwell C and Vickers hardness testing, shear punch testing (SPT) and pin-on-disk wear test. After the FSP, the hard B2 phases, which were formed during casting, were broken and along with the TiO2 nanoparticles distributed uniformly in the matrix. These changes resulted in increase in hardness and shear strength from 301 HV to 485 HV and 332–411 MPa amounts, respectively for initial and FSPed cases; however, the wear resistance of the FSPed specimen decreased by approximately 60% compared to the initial condition.

Characterization of galling during dry and lubricated punching of AA5754 sheet

When sheets of aluminum alloys are pierced or trimmed, tool failure occurs by the transfer of material from the sheet to the surface of the tool. This phenomenon referred to as galling adversely affects sheared edge quality and increases energy consumption. An instrumented pneumatic press was designed and built to conduct shear–punch tests on 2 mm-thick AA5754-O sheets and to investigate the progression of galling to AISI M2 steel punching tools during dry and lubricated punching. The punching tests were performed using a clearance of 2.0% of the lower die diameter. Cumulative galling volumes were measured using a non-contact optical surface profilometer, and the rate of material transfer (the galling rate) was estimated for both dry and lubricated punching. The galling initially occurred at a high rate, and for dry punching, it was reduced to 74.6×104μm3/stroke between 20th and 125th strokes. Lubricating the aluminum sheet with an oil-based lubricant mitigated the material transfer, and the galling rate after the 20th stroke was reduced to 3.1×104μm3/stroke. Punching force-displacement curves indicated a higher amount of energy expended to shear AA5754-O sheets in the dry punching compared to the lubricated punching that is suggested to be due to the higher galling resulting in higher friction forces at the interface.

Evolution of mechanical properties, microstructure and texture and of various brass alloys processed by multi-directional forging

This study investigated mechanical properties and texture evolution of Cu-xZn alloys (x = 5, 15, 20, 30) processed by multi-directional forging (MDF) up to 6 passes at ambient temperature. Mechanical properties were examined via shear punch and hardness tests. Optical microscopy and high-resolution scanning electron microscopy (HR-SEM), equipped with electron backscattered diffraction (EBSD) detector were also utilized to characterize the detailed microstructures and texture evolutions. The MDFed Cu-xZn alloys after 6 passes showed superior mechanical properties without the reduction of electrical conductivity. Hardness, ultimate shear strength and shear yield strength of Cu-30Zn alloy improved by 213%, 83% and 85%, respectively after 6 passes of MDF. Enhancement of mechanical properties can be attributed to grain refinement. The MDFed Cu-5Zn alloy presented a predominantly Copper-type texture due to the higher activity of shear bands. By increasing Zn to Cu-15Zn and Cu-20Zn, Brass and Goss texture components were observed. Finally, Cu-30Zn alloy possessed a Brass texture which could be attributed to a higher amount of twinings.

Investigation of shear and tensile mechanical properties of ZK60 Mg alloy sheet processed by rolling and sheet extrusion

The microstructure, texture and mechanical behavior of two wrought ZK60 magnesium alloys were investigated by tensile test and shear punch test (SPT). The samples processed by hot rolling and the combination of hot rolling and sheet extrusion techniques. The mechanical properties of the alloys correlated to the microstructural characteristics and the texture. Microstructural analysis showed that extrusion transformed the equiaxed coarse grain structure of the rolled sample with an average grain size of 68 μm to a bimodal structure including very fine dynamically recrystallized (DRX) grains, having an average grain size of ∼2.8, and large elongated deformed grains. The sheet extrusion process improved the tensile yield stress, the ultimate tensile strength, the shear strength, and the tensile elongation to failure. The strength enhancement was attributed to the finer grain size and the change of the volume fraction of the secondary phase particles. It was demonstrated that extrusion could improve both strength and ductility at room temperature in wrought ZK60 alloy. Although the tensile ductility improved after extrusion, it was shown that deformability in SPT remains unchanged after extrusion. Microstructural observations show that in SPT the positive effect of the grain refinement on the ductility was compensated by the hindering effect of Mg4Zn7 particles on the glide of <c+a> pyramidal dislocations. This slip is a dominant mechanism of deformation during SPT due to the basal texture.

Effects of processing parameters on the fracture behaviour of cold roll bonded and accumulative roll bonded Al–Cu lamellar composites

Al–Cu composites were fabricated by cold roll bonding (CRB) and accumulative roll bonding (ARB) processes. The effects of different parameters were investigated on the failure mechanism of the composites. A scanning electron microscope (SEM) and an optical microscope (OM) were used to characterise the microstructures of the resulting composites. The peeled surfaces of the CRBed material revealed that micro-cracks were formed almost perpendicular to the rolling direction and caused the premature failure of the bonding during the peeling test. Also, tensile, microhardness and shear punch tests were conducted on the Al–Cu composites produced under different conditions. Failure analysis of the non-heat-treated composites revealed that the layers separated from the middle of ARBed specimens. However, these centre-line separations were alleviated in composites subjected to heat treatment, even though the initiation of inter-lamellar micro-cracks were observed due to the formation of intermetallic compounds for heat-treated specimens.

Influence of high pressure torsion on microstructure evolution and mechanical properties of AZ80/SiC magnesium matrix composites

The effect of applying 1, 5 and 10 turns of high pressure torsion (HPT) as a severe plastic deformation technique on the microstructural evolution, hardness, tensile and shear strength of an as-cast AZ80-SiC magnesium matrix composite is investigated in the present study. The results show that HPT at room temperature refines the microstructure of the as-cast material having an average grain size of 176 ± 58.9 μm to a fine grain structure with average grain sizes of 4.2 ± 4.1 μm and 2.5 ± 2.1 μm in 5 and 10 turns HPT samples, respectively. In addition, ultra-fine grained regions (grain size <1 μm) with volume fractions of about 12, 27 and 31 vol% are obtained in the samples processed by 1, 5 and 10 turns of HPT, respectively. Based on microstructural observations, it is concluded that 5 and 10 turns HPT samples are almost similar in terms of grain size, recrystallized fraction, low-angle grain boundary fraction, and recovered parts. The ultimate tensile and shear (achieved from shear punch tests) strengths of the as-cast sample are improved by applying HPT due to grain size and texture hardening mechanisms. The highest strength values are obtained after performing the first HPT turn due to the more significant effect of texture hardening in comparison to the 5 and 10 turns HPT-processed samples. Similar to the strength results, the hardness of the as-cast material is also enhanced from 66 ± 6 HV to about 123 ± 3 HV through HPT processing.

The micro/macro mechanical approach of reinforced braid composite used in tribology

Self-lubricant composite is a flourish scope of technology that merits academic and industry attention, as it is a specific part which essentially employed in acute operation conditions. In the present study, the mechanical properties of the self-lubricating composite of two-dimensional (2D) and three-dimensional (3D) braid were investigated. The composites contained Polytetrafluoroethylene (PTFE) fibers as a lubricant and glass, carbon, and Kevlar as a reinforcement, hierarchically incorporated into the structure. In order to study the composite behavior as well as to determine the modulus and hardness of the sample, an indentation test, which is very similar in loading to abrasion tests, was applied. A microband test was also conducted to assess the adhesion between the resin and the PTFE fiber. Shear punch tests were performed to evaluate the total shear strength and impact test to estimate energy absorption and impact strength. The results showed that PTFE/epoxy matrix has poor adhesion. Composites with higher PTFE volume fraction had good energy absorption and, at the same time, low shear strength. The higher modulus of carbon composites was concerned.

Characterization of AA6111 aluminum alloy thin strips produced via the horizontal single belt casting process

ABSTRACT In this research, AA6111 aluminum alloy strips, 250 mm wide and ~6 mm thick, were produced via the horizontal single belt casting process. The strip microstructure was analyzed using optical and scanning electron microscopy, and the measured average grain size was 90 μm. This is significantly smaller than the average grain size of the products produced via direct chill (DC) casting route (i.e., 231 μm). An analysis of intermetallic compounds was also conducted using energy dispersive spectroscopy. These were observed to be distributed within and along the grain boundaries and are enriched in Mg, Si, and Cu. The shear punch test was performed to determine the ultimate tensile strength of the cast strip, which was observed to be 280 MPa. This value is significantly higher than the strength documented in the literature for DC cast products. A 3D profilometer was used to determine the top and bottom surface roughness of the as-cast AA6111 strips. The strip top surface was found to lie within 120 μm range, whilst the bottom surface roughness was less than 30 μm.

Effect of Mn addition on the microstructure, mechanical properties and corrosion resistance of a biodegradable Mg–Gd–Zn alloy

The effect of 0.5 and 1 wt% Mn additions on the microstructure, mechanical properties, and biocorrosion resistance of an extruded Mg–3Gd–1Zn (GZ31) alloy was investigated. Mn addition refined the grain structure so that the grain size decreased from 3.7 μm for the GZ31 alloy, to 2.3 μm for GZ31–1Mn alloy. Hardness measurements and shear punch tests (SPT) revealed that by adding 1 wt% Mn, the hardness, shear yield stress (SYS) and ultimate shear strength (USS) increased from 61 to 66 Hv, 102.0 to 128.5 MPa, and 142.8 to 152.4 MPa, respectively. The main mechanisms responsible for the improvement of mechanical properties were grain refinement and higher volume fraction of the second phase particles formed by Mn addition. Electrochemical impedance spectroscopy showed that the addition of 1 wt% Mn increased the overall corrosion resistance from about 515.4 Ω cm2 to 5883.6 Ω cm2. In addition, initiation of the inductive loop in the Nyquist diagrams of the Mn-containing alloys, in the lower frequencies in comparison to the base alloy, can be a sign of retarding the onset of pitting corrosion. The improved corrosion resistance of these alloys was due to the refined microstructure and formation of a more stable protective layer on the surface.

Microstructure, texture, and mechanical properties of the extruded and multi-directionally forged Mg–xGd alloys

The microstructural and textural evolutions as well as room-temperature mechanical properties of three binary Mg–Gd alloys with 1, 2, and 3 wt% of Gd were studied in the as-extruded condition and after two, four, and six passes of multi-directional forging (MDF). Microstructural observations of the extruded samples were indicative of partial dynamic recrystallization resulting in bimodal grain structures comprised of elongated un-recrystallized patches and fine recrystallized grains. After six passes of the MDF process, the fraction of the un-recrystallized regions decreased because of dynamic recrystallization, and thus, relatively uniform microstructures were achieved in all alloys. The greater fraction of the un-recrystallized patches and the finer grains in the recrystallized regions of the Mg–3Gd alloy confirmed the more pronounced retardation of recrystallization via solute drag mechanism at the higher Gd concentrations. Evaluation of crystallographic texture revealed that by applying the MDF process, the conventional fiber texture of the extruded condition was replaced with a new randomized texture, in which the basal planes had a tendency to rotate at angles of lower than 90° to the transverse direction. Mechanical properties were evaluated using shear punch testing (SPT) and the results showed that with increasing the number of MDF passes in each alloy, the achieved finer grain structure was responsible for improving the shear strength. In addition, increasing the Gd content of the alloys resulted in finer grain size, more solute atoms, and higher fraction of Mg 5 Gd second phase particles, all of which led to the enhancement in shear strength.

Evaluation of the Mechanical Properties of Precipitation-Hardened Martensitic Steel 17-4PH using Small and Shear Punch Testing

Evaluation of the Mechanical Properties of Precipitation-Hardened Martensitic Steel 17-4PH using Small and Shear Punch Testing

Insight into the effect of weld pitch on the microstructure-properties relationships of St 37/AISI 316 steels dissimilar welds processed by friction stir welding

This research aims to evaluate the effect of weld pitch on the microstructure and properties of St 37/AISI 316 steels friction stir welds. The microstructure and microtexture of the samples were studied by means of electron backscatter diffraction analysis. The mechanical behaviors of the weldments were also investigated by microhardness, shear punch testing, and uniaxial tensile testing. In addition, the corrosion behavior of the welds was also evaluated. It was observed that the weld pitch of 0.0830 or 0.0625 mm/rotation resulted in producing defect-free welds with acceptable tensile strength level. Moreover, hardness and shear strength of the weld zone were improved up to 57% and 74%, respectively as compared to the base metals. It was due to the grain refinement which occurred within the stir zones by activating the dynamic recrystallization mechanism. Initial texture components of the base metals were replaced by recrystallized texture components in the stir zones. Orientation of grains in the stir zones was found to be highly dependent on the weld pitch. Regarding the corrosion resistance, the obtained results revealed that stir zone of St 37 steel was the weakest part of the weldments. Overall, the weldment employing the weld pitch of 0.0625 mm/rotation was found to achieve superior microstructural features and optimum properties.

Microstructure and Mechanical Properties of Spark Plasma Sintered Nanocrystalline TiAl-xB Composites (0.0 &lt;x&lt;1.5 at.%) Containing Carbon Nanotubes

This paper investigates the effects of minor additions of carbon nanotubes (CNTs) and boron on the structure and mechanical properties of nanocrystalline TiAl intermetallic compound. Nanocrystalline TiAl-xB(0.0 < x < 1.5 at.%) composites containing 1 wt.% CNT were synthesized by mechanical alloying and spark plasma sintering. Microstructure and mechanical properties of samples were evaluated using a scanning electron microscopy, energy-dispersive x-ray spectroscopy, elemental mapping, differential scanning calorimetry, Vickers hardness measurement, and shear–punch test. The findings of the current study show that milling up to 40 h results in the formation of Ti(Al) solid solution. Further milling up to 60 h is associated with a complete amorphization of the structure. Results also show that spark plasma sintering leads to the transformation of Ti(Al) solid solution into a mixture of Ti3Al, Ti2Al, and TiAl intermetallic compounds. Minor additions of boron and CNTs cause a significant grain refinement. The addition of the latter significantly improves the elongation as well. The implications of boron/CNT additions for the microstructure of TiAl and how it correlates with the mechanical properties are thoroughly discussed in this paper.

Microstructure and superplasticity of Mg–2Gd–xZn alloys processed by equal channel angular pressing

Abstract Microstructure, mechanical properties and superplastic behavior of Mg–2Gd–xZn (x = 0, 1, 2 and 3 wt%) alloys were investigated after extrusion and equal channel angular pressing (ECAP). After only 2 passes of ECAP, a homogenous fine-grained microstructure with a grain size of 2.33 μm and a high fraction of high-angle grain boundaries of 84% were formed in the Mg–2Gd–3Zn (GZ23) alloy, while 4 ECAP passes were necessary to create such a structure in the other alloys. This was attributed to the higher solute drag effect in the other alloys, retarding dynamic recrystallization (DRX). Although DRX occurred more easily in the GZ23 alloy, the final DRX grain size was slightly coarser compared to the other alloys. Shear punch testing (SPT) showed that grain refinement during ECAP leads to a slight increase in the shear yield strength of all studied materials after 2 ECAP passes, which was mostly balanced by texture softening caused by the shear texture component and grain growth after 4 ECAP passes. Contrary to the other alloys, the GZ23 alloy exhibited superplastic behavior after a lower number of ECAP passes. In addition, the superplastic temperature for GZ23 was 648 K, which was lower than the 673 K observed for the other alloys. The m-values of ~0.45–0.5 and activation energies of 98–114 kJ/mol suggested grain boundary sliding (GBS) controlled by grain boundary diffusion as the dominant deformation mechanism in the superplastic regime. This was confirmed by microstructural observations.

Effects of pre-heat treatment of the consumable rod on the microstructural and mechanical properties of the friction surfaced Al-Cu-Mg alloy over pure aluminum

In this study, the effects of the traverse speed and the pre-heat treatment of the AA2024 consumable rod on the mechanical and microstructural properties of the friction surfaced coating over AA1050 aluminum are investigated. The mechanical and microstructural properties of the coatings are characterized using optical and scanning electron microscopy, macrotexture measurement using X-ray diffraction, and the shear punch test. The results show that in both coatings fabricated by solid solutionized and T3-treated consumable rods, by increasing the traverse speed, the deposition rate decreases, leading to a reduction in the volume of the deposited material. Moreover, the T3 heat treatment of the consumable rod results in a smaller grain size in the coating. Regardless of the consumable rod's pre-heat treatment conditions, the size of the Al2CuMg precipitates in the coating increases by increasing the traverse speed. Friction surfacing using a solid solutionized consumable rod increased and decreased the shear and recrystallization texture in the coating, respectively. The smaller grains, fine precipitates, and a stronger recrystallization texture in the coatings fabricated by T3-treated consumable rod led to higher levels of strength and hardness in these coatings.

Microstructural evolution and superplastic behavior of a fine-grained Mg−Gd−Y−Ag alloy processed by simple shear extrusion

Abstract Two magnesium alloys with the nominal compositions of Mg−6Gd−3Y (GW63) and Mg−6Gd−3Y−1Ag (GW63−1Ag) were hot extruded and then processed by 6 passes of the simple shear extrusion (SSE) process at 553 K. Both SEM and EBSD studies confirmed the mean grain size reduction of the extruded base GW63 alloy from 10.1 to 2.9 μm by adding 1 wt% Ag. This decrease in the grain size was due to the formation of the Ag-containing precipitates with network-type morphology at the grain boundaries of the extruded GW63−1Ag alloy. Further grain refinement was achieved after SSE through the occurrence of DRX in both Ag-free and Ag-containing alloys. However, the GW63−1Ag alloy showed a higher fraction of DRX grains and HAGBs after SSE processing compared to the Ag-free alloy. The enhanced DRX behavior was attributed to the smaller initial grain size of the Ag-containing alloy in the as-extruded condition and the role of Ag addition in suppressing the solute drag effect of the segregated Gd and Y elements at the grain boundaries. The superplastic behavior of the alloys was assessed via the shear punch testing (SPT) method performed in the temperature ranges of 623–723 K for the extruded specimens and 573–673 K for the SSE processed alloys. It was revealed that none of the extruded alloys exhibited superplastic flow, because of their large grain sizes. The GW63 alloy processed by 6 passes of SSE displayed a maximum m-value of 0.38 at 648 K, while the high strain rate sensitivity (SRS) index of 0.5 was measured at 623 K for the Ag-containing alloy after SSE. This was accompanied with a superplastic deformation behavior of the latter alloy, for which an activation energy of 105 kJ mol−1 that is close to that of the grain boundary diffusion of pure Mg was obtained. Therefore, grain boundary sliding (GBS) associated with grain boundary diffusion was introduced as the dominant deformation mechanism during the superplastic flow of the Ag-containing alloy processed by SSE.