Highest UTS Research Articles

Uterine disease and its effect on subsequent reproductive performance of dairy cattle: a comparison of two cow-side diagnostic methods

The aim of this study was to compare vaginal mucus scoring and ultrasonographic assessment of uterine content as predictors of future reproductive performance of dairy cows. Holstein-Friesian cows (n = 493) from seven commercial dairy farms were enrolled in this study. All cows received one prebreeding examination (PBE) between 21 and 38 days after parturition. During the PBE, vaginal mucus was scored (MS) and the transrectal ultrasonographic examination of the uterus to assess content (UTS) took place. The MS was scored on a scale of 0 to 3 using a Metricheck device and appearance of the uterus on transrectal ultrasound was scored on a scale of 0 to 4 based on the presence and consistency of intraluminal fluid. Other data collected from each cow included the farm ID (F_ID), conception rate to first service, length of breeding window, lactation number, calving month, body condition score (BCS) at calving, BCS loss after calving, BCS at PBE, days in milk at PBE, 305 day milk yield, economic breeding index (EBI), EBI fertility subindex and EBI health subindex. For each cow these parameters were analyzed using univariate Cox proportional hazard model to evaluate the effect of variables on the reproductive performance, measured as positive pregnancy status (PS) at the end of the breeding season. Receiver-operating characteristic analysis of the diagnostic tests compared with each other took place as well. Cows with positive UTS were 7.75 times more likely to have a positive MS as well (P < 0.01). The PS hazard ratios for cows with UTS0, 1, 2, 3, and 4 were 1; 0.84; 0.53; 0.78; 0.28, respectively (P < 0.001). For the cows with MS0, 1, 2, and 3, the PR hazard ratios were 1; 1.02; 0.51; 0.75; respectively (P = 0.01). Conception rate to first service, breeding window, and PS were significantly better for the cows with UTS0, 1 and 2 compared with the cows with UTS3–4 and MS2+3 (68%; 18%, [P = 0.020]; 29; 75 days, [P = 0.001]; 95%; 55%; [P = 0.010], respectively). There was a significant effect of days in milk at PBE in relation to the subsequent PS (P = 0.04). Cows in lactation number 5 or more were less likely (r = 0.69) to get in calf before the end of the breeding season than cows in their first lactation. Cows that calved later in the season were less likely to become pregnant before the end of the breeding season (P < 0.03). Younger cows (lactation <5) and cows with MS and UTS scores of 0 and −1 had significantly better reproductive performance (P < 0.04). Receiver-operating characteristic analysis showed that MS did not always reflect UTS, but cows with positive UTS were 7.75 times more likely to have a positive MS (P < 0.01) and a high UTS had a larger negative effect on time to PS than a high MS (P < 0.05). In conclusion, both prebreeding vaginal mucus evaluation with the Metricheck device and an ultrasound scan of the uterus serve as a good predictor of the subsequent PS. There is overlap between the two systems, but the best predictor for future reproductive outcome of the cow is a combination of both.

Determination of α/β phase boundaries and mechanical characterization of Mg-Sc binary alloys

In this study, α(hcp)/β(bcc) phase boundaries of the Mg-Sc binary phase system were determined by Mg/Sc diffusion couple and conventional equilibrated alloy methods. It was confirmed that α/β phase boundaries exist in regions with a higher Mg content than those in reported diagram. The Mg-Sc alloy with a β single-phase showed tensile strength of 254MPa and elongation of 25.4%. The tensile strength of the Mg-Sc alloy increased with increasing volume fraction of the α phase (fα) and the alloy with a fα of 34% showed high UTS of 310MPa and elongation of 28.8%, properties which are better balanced than those of conventional Mg alloys. This improvement was suggested to be due to isotropic deformation of the β phase, small grain size and small c/a of the α phase.

The effects of Mg2Si(p)on microstructure and mechanical properties of AA332 composite

This paper describes a study on the effects of <TEX>$Mg_2Si_{(p)}$</TEX> addition on the microstructure, porosity, and mechanical properties namely hardness and tensile properties of AA332 composite. Each composite respectively contains 5, 10, 15, and 20 wt% reinforcement particles developed by a stir-casting. The molten composite was stirred at 600 rpm and melted at <TEX>$900^{\circ}C{\pm}5^{\circ}C$</TEX>. The <TEX>$Mg_2Si$</TEX> particles were wrapped in an aluminum foil to keep them from burning when melting. The findings revealed that the microstructure of <TEX>$Mg_2Si_{(p)}/AA332$</TEX> consists of <TEX>${\alpha}$</TEX>-Al, binary eutectic (<TEX>$Al+Mg_2Si$</TEX>), <TEX>$Mg_2Si$</TEX> particles, and intermetallic compound. The intermetallic compound was identified as Fe-rich and Cu-rich, formed as polygonal or blocky, Chinese script, needle-like, and polyhendrons or "skeleton like". The porosity of <TEX>$Mg_2Si_{(p)}/AA332$</TEX> composite increased from 8-10% and the density decreased from 9-12% from as-cast. Mechanical properties such as hardness increased for over 42% from as-cast and the highest UTS, elongation, and maximum Q.I were achieved in the sample of 10% <TEX>$Mg_2Si$</TEX>. The study concludes that combined with AA332, the amount of 10 wt% of<TEX>$Mg_2Si$</TEX> is a suitable reinforcement quantity with the combination ofAA332.

Effect of heat treatment and number of passes on the microstructure and mechanical properties of friction stir processed AZ91C magnesium alloy

In this paper, the effect of heat treatment and number of passes on microstructure and mechanical properties of friction stir processed AZ91C magnesium alloy samples were investigated. From six samples of as-cast AZ91C magnesium alloy, three plates were pre-heated at temperature of 375°C for 3 hours, and then were treated at temperature of 415°C for 18 hours and finally were cooled down in air. Three plates were relinquished without heat treatment. 8 mm thick as-cast AZ91C magnesium alloy plates were friction stir processed at constant traverse speed of 40 mm/min and tool rotation speed of 1250 rpm. After process, microstructural characterization of samples was analyzed using optical microscopy and tensile and Vickers hardness tests were performed. It was found that heat treated samples had finer grains, higher hardness, improved tensile strength and elongation relative to non-heat treated ones. As the number of passes increased, higher UTS and TE were achieved due to finer grains and more dissolution of β phase (Mg17Al12). The micro-hardness characteristics and tensile improvement of the friction stir processed samples depend significantly on grain size, removal of voids and porosities and dissolution of β phase in the stir zone.

The effect of postproduction heat treatment on γ-TiAl alloys produced by the GTAW-based additive manufacturing process

Postproduction heat treatments were carried out on additively manufactured γ-TiAl alloys that were produced by using the gas tungsten arc welding (GTAW) process. The microstructural evolution and mechanical properties of both as-fabricated and heat-treated specimens were investigated to assess the effect of different heat treatment conditions, by using optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Neutron Diffraction and tensile tests.The results indicated that heat treatment promotes the formation of the γ phase in the majority region after heat treatment at 1200°C for 24h, while a fully lamellar structure was formed in the near-substrate zone. The response to heat treatment at 1060°C/24h was markedly different, producing a fine lamellar structure with differing sizes in the majority region and near-substrate zone. These various microstructural characteristics determined the mechanical properties of the heat-treated samples. The heat-treated samples at 1200°C/24h exhibited lower UTS and microhardness values but higher ductility than the as-fabricated samples without heat treatment, while the 1060°C/24h heat treatment resulted in higher UTS and microhardness values but lower ductility. Due to the homogenous microstructure in the majority region after each postproduction heat treatment, the tensile properties were similar for both the build direction (Z) and travel direction (Y), thereby minimising the anisotropy that is exhibited by the as-fabricated alloy prior to heat treatment.

Effects of thermal treatments on microstructure and mechanical properties of a Co–Cr–Mo–W biomedical alloy produced by laser sintering

Direct Metal Laser Sintering (DMLS) technology based on a layer by layer production process was used to produce a Co–Cr–Mo–W alloy specifically developed for biomedical applications. The alloy mechanical response and microstructure were investigated in the as-sintered state and after post-production thermal treatments. Roughness and hardness measurements, and tensile and flexural tests were performed to study the mechanical response of the alloy while X-ray diffraction (XRD), electron microscopy (SEM, TEM, STEM) techniques and microanalysis (EDX) were used to investigate the microstructure in different conditions. Results showed an intricate network of ε-Co (hcp) lamellae in the γ-Co (fcc) matrix responsible of the high UTS and hardness values in the as-sintered state. Thermal treatments increase volume fraction of the ε-Co (hcp) martensite but slightly modify the average size of the lamellar structure. Nevertheless, thermal treatments are capable of producing a sensible increase in UTS and hardness and a strong reduction in ductility. These latter effects were mainly attributed to the massive precipitation of an hcp Co3(Mo,W)2Si phase and the contemporary formation of Si-rich inclusions.

Effect of Welding Conditions on the Mechanical Properties of Friction Stir Welded 1050 Aluminum Alloy

Friction stir welding (FSW) is a relatively new solid-state joining process. This joining technique is energy efficient, environmental friendly, and versatile. In order to demonstrate the friction stir weldability of the 1050-H14 aluminum alloy and determine optimum welding parameters, the mechanical and metallurgical properties of the joints have been studied in this paper. The rational speed was changed from 900 to 1400 rpm while the traverse speed was varied from 25 to 40 mm min-1. The results showed that all the properties studied were significantly affected by the welding process parameters. Optimized welding conditions of 1400 rpm rotational speed and 25 mm min-1 feed rate resulted in the highest UTS of the FSW joint which was equivalent to 86% that of the base material. Also, the combination of 900 rpm rotational speed and 40 mm min-1 traverse speed resulted in the best joint hardness efficiency of about 83% that of the base metal.

Mechanical properties of ultrafine-grained AlZnMg(Cu)-alloys AA7020 and AA7075 processed by accumulative roll bonding

Ultrafine-grained AA7020 (AlZnMg) and AA7075 (AlZnMgCu) were produced by accumulative roll bonding (ARB) with up to 6 cycles. Different pre-heating treatments and their effect on the mechanical performance of the materials were investigated by means of hardness measurements and uniaxial tensile testing. It was found for AA7020 that by pre-heating at 230 °C for 2.5 min prior to each rolling step, an UTS of 550 MPa can be achieved, which is 51 % higher compared to the peak-aged T6 reference. For AA7075, pre-heating at 280 °C for 2.5 min leads to a very high UTS of 720 MPa after four ARB passes. A negative strain rate sensitivity was found for both alloys, which shifts toward zero with increasing number of ARB cycles. Post-ARB heat treatment was performed in order to overcome the reduced ductility after ARB. This leads to an enhanced strain hardening capacity after 4 cycles, resulting in an increase of the uniform elongation from 1.4 to 2.0 % for AA7020 and from 0.9 to 2.1 % for AA7075.

Changes of Mechanical Properties of AlSi7Mg0.3 Cast Alloy through Filtration

Molten aluminium alloy is so active that it an easily chemically react with O2and H2O to form Al2O3 inclusions and H during melting practice. However, some other inclusions form by process. Under turbulent flow conditions, the inclusions are distributed unevenly in molten aluminium alloy. They may associate with crack or by the location of crack initiation in solidified casting. Castings containing these inclusions will probably exhibit poor ductility or toughness. Therefore, the purification of the molten aluminium alloy is one of the most important processes for improving the quality of Al-products. The inclusions in molten secondary AlSi7Mg0.3 cast alloy (without refining or modification; grain refined with 55 ppm AlTi5B1 and modified with 20, 40 and 60 ppm AlSr10) were removed using depth filtration by ceramic foam and pressed filter. The results showed that the mechanical properties through filtration changes. Ductility and UTS of the filtered tensile specimens increases. The better mechanical properties were measured by the using of pressed ceramic filter. Highest UTS and ductility was observed for samples modified with 40 ppm of Sr. Filtration with ceramic filters have very significant influence on the porosity decreasing; in the process the better effect has a pressed filter. In samples modified with 60 ppm of Sr were observed effect of over modification (mechanical properties decreased; porosity increased).

Microstructure, Tensile Properties and Creep Resistance of Sub-rapidly Solidified Mg-Zn-Sn-Al-Ca Alloys

Abstract Microstructures, tensile properties and creep resistances of seven kinds of sub-rapidly solidified Mg-Zn-Sn-Al-Ca alloys were studied. Results show that as for the Mg- x Zn- y Sn-2Al-0.2Ca ( x + y =9, x / y =2, 1 and 0.5, in mass%) alloys, the highest UTS and YTS at RT are obtained with the Zn/Sn mass ratio of 1. The YTS at 150 °C increases but that at 200 °C decreases with the increase of Zn/Sn mass ratio. It is possibly ascribed to the elevated-temperature strengthening of Mg 2 Sn particles since the alloy with the lower Zn/Sn mass ratio contains a higher amount of Mg 2 Sn and a lower fraction of Zn-containing phases. As for the Mg-4.5Zn-4.5Sn-2Al- z Ca ( z =0, 0.2, 0.4 and 0.6) alloys, UTS and YTS increase at first and then decrease with the increase of Ca content at both RT and 200 °C. The strength peaks occur at 0.2% Ca and 0.4% Ca, respectively. Both the initial strain and the steady creep rate decrease with the increase of Ca content below 0.4% Ca at 200 °C under the compression stress of 55 MPa. Minor Ca addition can improve the RT and elevated temperature strength and enhance the compressive creep resistance of the Mg-4.5Zn-4.5Sn-2Al alloy, but reduce the elevated-temperature plasticity. In addition, it also has an obvious influence on the tensile fracture mode, which changes from cleavage to quasi-cleavage at RT and from ductile to quasi-cleavage at 200 °C with the increasing of Ca addition.

A Comprehensive Laboratory Screening of Three-Step Etch-and-Rinse Adhesives

This study evaluated several bonding (microtensile bond strengths [μTBS], nanoleakage [NL], and in situ degree of conversion [ISDC] on dentin) and mechanical properties (ultimate tensile strength [UTS], degree of conversion [DC], water sorption [WS], and solubility [SL] in water) of four three-step etch-and-rinse adhesives in the short term. A total of 28 molars were used in this study. The dentin surfaces were bonded with the following adhesives: All-Bond 3 (ALB3); Fusion Duralink (FSDL); Optibond FL (OBFL), and Scotchbond Multi-Purpose (SBMP). After each adhesive-system application, composite resin build-ups were added. For bonding tests, specimens were sectioned in order to obtain bonded sticks. The sticks were divided to be tested for μTBS (0.5 mm/min), for NL (n=2), and ISDC (n=2). For NL, they were immersed in 50% silver nitrate and analyzed by scanning election microscopy. For ISDC, the hybrid layer was evaluated by micro-Raman spectroscopy. An hourglass-shaped matrix (UTS) or disk-shaped matrix (WS and SL) was filled with primer and adhesive (1:1 ratio) and light-polymerized. For UTS evaluation, the specimens were tested under tension. For WS and SL, specimens were desiccated and stored in distilled water to evaluate water diffusion kinetics over a 28-day period. The DC of the adhesives was evaluated by Fourier transformed infrared spectroscopy. The data from each test were analyzed by appropriate statistical methods. OBFL resulted in the highest μTBS, lower NL, higher ISDC and DC, and higher UTS than other adhesives (p<0.05), as well as lower WS (similar to ALB3 and FSDL) and SL (similar to ALB3 and SBMP) (p>0.05). ALB3 showed a higher NL and the lowest DC value. FSDL showed the highest NL and SL and the lowest ISDC. SBMP showed the lowest pattern of WS (p<0.05)CONCLUSION: OBFL showed the best results in all the properties evaluated, and it can be considered the gold standard of the three-step etch-and-rinse adhesive systems.

Design of lead-free candidate alloys for low-temperature soldering applications based on the hypoeutectic Sn–6.5Zn alloy

The coupling effect of both minor alloying addition and reducing the amount of Zn phase have been proposed as an important strategy to improve the integrity and reliability of eutectic Sn–9Zn solder joints. In this work, the changes in microstructures, thermal behaviors and mechanical properties associated with the alloying of Ni and Sb to eutectic Sn–Zn after reducing the amount of Zn phase were explored. Thermal analysis confirmed that Ni and Sb additions being effective in reducing the amount of undercooling, while the melting temperature and pasty range remained at the hypoeutectic Sn–6.5Zn level. The resulting ultimate (UTS), yield tensile strength (YS) and elongation (El) of Sn–6.5Zn–0.5Ni and Sn–6.5Zn–0.5Sb alloys were experimentally determined and compared with the corresponding results of plain Sn–6.5Zn solder alloy. It was found that the Sn–6.5Zn–0.5Ni and Sn–6.5Zn–0.5Sb alloys examined comply with the compromise between high mechanical strength and ductility. Microstructural analysis revealed that the origin of change in mechanical properties was attributed to the enhanced solid solution effect of Sb and the flower shaped (Ni, Zn)3Sn4 intermetallics (IMC) phase produced by Ni addition. The Sn–6.5Zn–0.5Sb alloy has the highest UTS and appropriate ductility of all alloys examined. This finding indicates the capability of newly developed ternary solder alloys to serve a much wider array of value-added applications.

The Effects of Small Additions Ga and Al on the Microstructure and Tensile Properties of Sn-Zn Based Lead-Free Solders

The melting temperature, microstructures, and mechanical properties of the Sn-Zn-0.5Ag-0.5Ga, Sn-Zn-0.5Ag-0.45Al and Sn-Zn-0.5Ga-0.45Al lead-free solders were investigated. The results indicate that the addition of 0.5 wt% Ag to the Sn-Zn based alloys destroy the eutectic structure and results in the formation of Ag-Zn compound and hypoeutectic structure. The variation in the microstructure lowers the UTS. By the addition of Al the UTS and elongation of the 0.5Ag-0.45Al alloy can be decreased due to the Al diffused to the interface of the Ag-Zn compound/Sn-Zn eutectic structure to form Al-Zn compound. The 0.5Ga-0.45Al alloy shows a typical eutectic structure with the light contract β-Sn and the darker needle-like phase, as well as a small amount of Al-Zn phase with a near diamond shape. Gallium uniformly distributes in the Sn matrix and Zn rich phases. The 0.5Ga-0.45Al solder had the highest UTS and elongation, while 0.5Ag-0.45Al had the lowest UTS and elongation. The results indicate that Ga and Al exhibits prominent influence on the microstructure as well as the mechanical properties of the solders.

Microstructures and Mechanical Properties of a Novel Mg-Gd-Y-Zn-Zr Alloy

The microstructure characteristics and mechanical properties of as-cast and hot extruded Mg-5Gd-4Y-0.5Zn-0.5Zr (GWZ540) alloy were investigated. The results show that coarse the as-cast GWZ540 alloy consisted of α-Mg grain and two second phases, disc-like Mg5(Zn0.2Y0.2Gd0.6) and block-shaped Mg24(Y0.6Gd0.4)5. Hot extrusion resulted in a significant refinement of the α-Mg grains and a uniform distribution of the second phases, but with little effect on the composition and structure of the second phases. It is also shown that GWZ540 alloy exhibits higher UTS and TYS and elongation at both room and elevated temperature than those of WE54 alloy.

Influence of matrix characteristics on tensile properties of in situ synthesized TiC/TA15 composite

In the present paper, in situ synthesized 10vol.% TiC/TA15 composite has been fabricated by induction melting and common casting utilizing the reaction between titanium and C powder. Three types of heat treatment processes were performed on the as-cast composite and, accordingly, fine fully lamellar, bi-modal and near-equiaxed microstructures were obtained. The tensile properties were tested at room temperature, 600°C and 650°C. The results show that heat treatment can evidently enhance UTS below 600°C. The increased UTS is accompanied by the rapid decrease in tensile elongation at room temperature. As tensile temperature increases to 650°C, the discrepancy in UTSs of the composite with different matrix microstructures becomes small. The composite with fine fully lamellar microstructure exhibits a good combination of relatively high UTS and high tensile elongation in comparison with that with bi-modal and near-equiaxed microstructures. Below 650°C, the damage of the composite before and after heat treatment is mainly initiated by the fracture of TiC particles followed by the ductile failure of the matrix.

EFFECT OF FRICTION STIR PROCESSING CONDITION ON TENSILE PROPERTIES OF Al-7Si-0.3Mg CAST ALLOY

Multipass friction stir processing (FSP) of cast Al -7 Si -0.3 Mg alloy was conducted and FS microstructures were related to the fracture paths and tensile properties. It has been found that high rotation speed (ω) FS caused alignments of Si particles, providing easy paths for fracturing during loading and resulting in low elongation and lower UTS values of the processed alloy. The material flow mechanism during FS leading to the alignments is suggested. This suggested mechanism has been verified after conducting FS experiments using a lower ω value which eliminated Si particle alignments and thus allowed high elongation and UTS values to be attained.

Evaluation of Mechanical Properties and Microstructures of Casing-Drilling Steels

An investigation into the mechanical properties of K55，N80 and P110 steels was carried out for casing-drilling technology. The obvious presence of bright facets on broken K55 Charpy V-Notch (CVN) sample surfaces was indicative of the effect of microstructure on the cleavage fracture. The appearing of bright facet surfaces of K55 was attributed to the microstructure of ferrite and pearlite. The fracture surfaces of N80 and P110 CVN samples included quasi-cleavage fracture mechanism and dimple fracture mechanism, respectively. The tensile fracture surface of all three types of casing-drilling steels included dimple fracture mechanism, both the N80 and P110 specimen show higher UTS and impact energy values compared to the K55 specimen.

Effects of Cu content on microstructure and mechanical properties of Al–14.5Si–0.5Mg alloy

This study elucidates how Cu content affects the microstructure and mechanical properties of Al–14.5Si–0.5Mg alloy, by adding 4.65 wt.% and 0.52 wt.% Cu. Different Fe-bearing phases were found in the two alloys. The acicular β-Al 5FeSi was found only in the high-Cu alloy. In the low-Cu alloy, Al 8Mg 3FeSi 6 was the Fe-bearing phase. Tensile testing indicated that the low-Cu alloy containing Al 8Mg 3FeSi 6 had higher UTS and elongation than the high-Cu alloy containing the acicular β-Al 5FeSi. It is believed that the presence of the acicular β-Al 5FeSi in the high-Cu alloy increased the number of crack initiators and brittleness of the alloy. Increasing Cu content in the Al–14.5Si–0.5Mg alloy also promoted solution hardening and precipitation hardening under as-quenched and aging conditions, respectively. The hardness of the high-Cu alloy therefore exceeded that of low-Cu alloy.

An analysis of wrinkling limit diagrams of aluminum alloy 5005 annealed at different temperatures

This paper deals with the wrinkling limit diagrams for Aluminum alloy 5005 sheets having thickness of 2.00 mm annealed at four different temperatures namely 200°C, 300°C, 400°C and 500°C. The study pertains to deep drawing into cylindrical cups through conical die using a flat bottom punch. It is proved by these researchers and others that the onset of wrinkling takes place when the ratio of strain increments (der / deθ) or the ratio of strain (er / eθ) reaches a critical value during the drawing process. These values which could be determined experimentally over which the wrinkling takes place, is shown in the form of wrinkling limit diagrams for the above grade at different annealing temperature. An attempt is also made to develop the wrinkling theory that predicts the wrinkling based on results obtained in the form of wrinkling limit diagrams established for the above grade at different annealed temperature. Further it has been observed from the stress ratio that there is a clear curve, that separates the region from safe and the wrinkling region. Further it was observed that the annealed sheets having high n-value, high R-value and high UTS /σy ratio improve the resistance against wrinkling.

Microstructure and Mechanical Properties of Extruded Mg-Zn-Gd-Based Alloy Reinforced by Quasicrystals and Laves Phase

The microstructure and mechanical properties of Mg95.9Zn3.5Gd0.6 and Mg94.4Zn3.5Gd0.6Cu1.5 alloys reinforced by icosahedral quasicrystalline phase (I-phase) and Laves phase has been studied after extrusion at 573K. Extrusion can significantly refined the I-phase and Laves phase, and the strengthening effect of I-phase and Laves phase has been analyzed. Large volume of icosahedral phase in Mg95.9Zn3.5Gd0.6 has important role in its high UTS and elongation due to strong bonding effect at the I-phase/matrix interface for low interface energy. The Laves phase with cubic topological and close-packed structure in Mg94.4Zn3.5Gd0.6Cu1.5 alloy result in the higher heat resistance at elevated temperatures.