Ultimate Tensile Strength Values Research Articles

Design of Experiments to Compare the Mechanical Properties of Polylactic Acid Using Material Extrusion Three-Dimensional-Printing Thermal Parameters Based on a Cyber-Physical Production System.

The material extrusion 3D printing process known as fused deposition modeling (FDM) has recently gained relevance in the additive manufacturing industry for large-scale part production. However, improving the real-time monitoring of the process in terms of its mechanical properties remains important to extend the lifespan of numerous critical applications. To enhance the monitoring of mechanical properties during printing, it is necessary to understand the relationship between temperature profiles and ultimate tensile strength (UTS). This study uses a cyber-physical production system (CPPS) to analyze the impact of four key thermal parameters on the tensile properties of polylactic acid (PLA). Layer thickness, printing speed, and extrusion temperature are the most influential factors, while bed temperature has less impact. The Taguchi L-9 array and the full factorial design of experiments were implemented along with the deposited line's local fused temperature profile analysis. Furthermore, correlations between temperature profiles with the bonding strength during layer adhesion and part solidification can be stated. The results showed that layer thickness is the most important factor, followed by printing speed and extrusion temperature, with very close influence between each other. The lowest impact is attributed to bed temperature. In the experiments, the UTS values varied from 46.38 MPa to 56.19 MPa. This represents an increase in the UTS of around 17% from the same material and printing design conditions but different temperature profiles. Additionally, it was possible to observe that the influence of the parameter variations was not linear in terms of the UTS value or temperature profiles. For example, the increase in the UTS at the 0.6 mm layer thickness was around four times greater than the increase at 0.4 mm. Finally, even when it was found that an increase in the layer temperature led to an increase in the value of the UTS, for some of the parameters, it could be observed that it was not the main factor that caused the UTS to increase. From the monitoring conditions analyzed, it was concluded that the material requires an optimal thermal transition between deposition, adhesion, and layer solidification in order to result in part components with good mechanical properties. A tracking or monitoring system, such as the one designed, can serve as a potential tool for reducing the anisotropy in part production in 3D printing systems.

Evolution of Mechanical Properties of Pb–Sb–Sn–As–Se Grid Alloys for Lead-Acid Batteries During Natural Aging

This study is devoted to the investigation of mechanical properties of a series of low-antimony Pb–Sb–Sn–As–Se grid alloys for lead-acid batteries in as-cast condition and after natural aging during storage. Mechanical properties were characterized by ultimate tensile strength, yield strength, elongation, and Young's modulus determined at room temperature using TIRAtest 2300 and P-0.5 universal testing machines. For most investigated as-cast alloys, an increase in ultimate tensile strength is accompanied by an increase in elongation. Within the temperature range between 70 ºС and 150 ºС, higher heating temperature of a casing mold does not markedly affect average elongation but causes the slight decrease (by ~4 %) in average ultimate tensile strength. When aged during storage for 30–33 days, the Pb–Sb–Sn–As–Se grid alloys, attain higher values of ultimate tensile strength, yield strength, and Young's modulus but lower values of elongation. This is due to precipitation of second-phase particles from lead-based solid solution oversaturated by antimony, arsenic, and selenium. The most noticeable effect of strengthening is observed during first five days of natural aging.

Machine learning aided process design of Fe-Cr-Ni-Al/Ti multi-principal element alloys for excellent mechanical properties

Fe-Cr-Ni-Al/Ti multi-principal element alloys (MPEAs) with the good mechanical properties were designed by utilizing machine learning (ML) methods in our previous work. It can be noted that the post-processing (thermo-mechanical treatments, TMT) can tailor microstructures of the designed MPEAs with an aim to further obtain excellent mechanical properties. However, for a novel MPEA, determining the optimal post-processing parameters often requires time-consuming and laborious experiments due to the absence of existing precedents. In this work, we collected approximately 400 sets of mechanical properties data of MPEAs. The various feature selection methods were employed to train ML models for the process optimization of MPEAs. In addition, two input strategies were compared to offer a simplified approach for model inputs: one considering all process features and the other focusing solely on TMT process. The results showed that the difference in model accuracy between the two input strategies was minimal, indicating a strong possibility to simplify the ML model by disregarding specific processing features. Based on the trained models, we conducted optimization design for the TMTed parameters of Fe-Cr-Ni-Al/Ti MPEAs. The as-TMTed (Fe10Cr35Ni55)95Al5 and (Fe10Cr35Ni55)97Al2Ti1 samples demonstrated a balance between strength and toughness, with yield strength (YS) and ultimate tensile strength (UTS) values of approximately 600 MPa and 900 MPa, respectively, and a fracture elongation (FE) exceeding 30 %. As compared to samples without the TMT process in our previous work, the as-TMTed samples demonstrated a significant increase in YS and UTS, while only a certain loss in FE. This work confirmed the viability of ML-assisted efficient design for post-processing treatment in novel MPEAs.

Carboxymethyl Cellulose-Amuniacum Gum Based Edible Films Enriched with Clove Essential Oil: Optimization Formulation Using Response Surface Methodology (RSM)

Backgraound: Polysaccharides, particularly Carboxymethyl Cellulose (CMC) and Ammoniacum Gum (AMG), are considered valuable due to their thermal stability and non-toxicity. CMC has good film-forming ability but weak mechanical properties, while AMG shows promise with its unique chemical composition. Additionally, essential oils, such as Clove Essential Oil (CEO), are being used to enhance the antimicrobial properties of edible films, offering a natural way to extend the shelf life of food products.
 Methods: This study investigated the combined effect of CMC: 0.5-1.5 wt %, AMG: 1-5 wt %, as well as CEO: 0-30 v/v % on the physical characteristics of the CMC-AMG films by Response Surface Methodology. The optimization was performed with the aim of maximizing Whiteness Index, Ultimate Tensile Strength (UTS), and Strain at Break (SB) and minimizing total color difference (ΔE) values. Fourier-Transform Infrared Spectroscopy, film microstructure, Differential Scanning Calorimeter analysis, and antibacterial activity were investigated. The analysis was conducted using Design Expert software version 10.00 (STAT-EASE Inc., Minneapolis, USA).
 Result: The films with the highest UTS have been obtained through a composition of 5 g CMC, 1.5 g AMG, and 15% CEO. On the contrary, using a composition of 5 g CMC, 1 g AMG, and 30% CEO revealed the highest SB (115.41%). The highest UTS value of 13.17 MPa was obtained with a formulation consisting of 5% AMG, 1.5% CMC, and 15% CEO. Nevertheless, the maximum SB value of 115.41% was achieved with a formulation containing 5% AMG, 1% CMC, and 30% CEO. Moreover, heterogeneous microstructure and more opaque films were obtained as identified by the higher ΔE. The Differential Scanning Calorimeter results demonstrated that incorporating a CEO did not impinge on thermal stability. Furthermore, the addition of CEO led to a rise in antimicrobial activity against Salmonella enterica, Pseudomonas fluorescens, Escherichia coli, and Listeria monocytogenes.
 Conclusion: In conclusion, combination of CMC and AMG in optimum levels, led to the production of a film with acceptable mechanical properties. Also, these films showed significant antimicrobial activity.

Tailoring the brittle phase precipitation and mechanical properties in developing ultra-super ferritic stainless steels by Al modification

An isothermal ageing experiment was carried out to investigate the influence of Al modification on the brittle phase precipitation behaviour, grain coarsening and mechanical properties of newly designed ultra-super ferritic stainless steel. Experimental results demonstrated that the modification of Al significantly inhibited the formation rate of the sigma phase, retarded the induction period of the chi phase, and promoted the growth process of the Laves phase. Meanwhile, the calculated grain growth kinetics of the surface layer and core layer were compared with the measured values. It was found that the Al modification enhanced the effect of Laves phase precipitation pinning and solid solution drag, which slowed the grain coarsening rate. With the modification of Al, the values of ultimate tensile strength, yield strength (0.2% proof stress) and total elongation increased compared to those of the Al-free alloys. The plasticity of the Al-modified alloys was improved with the retardation of sigma and chi phases at the grain boundary. This study provided valuable insights for the development of Al-modified ultra-super ferritic stainless steels with low precipitation brittleness tendency.

Preparation of Mg-6Zn-1Y-0.5Zr alloy sheet with excellent mechanical properties and electromagnetic interference shielding effectiveness by extrusion plus rolling

Magnesium (Mg) alloy sheets with excellent mechanical properties and electromagnetic interference shielding effectiveness (EMI SE) have great application prospects. This study investigates the microstructure, mechanical properties, and EMI SE of extruded and rolled Mg-6Zn-1Y-0.5Zr sheets. In the Mg-6Zn-1Y-0.5Zr alloy subjected to extrusion and rolling, the predominant internal second phases are Mg-Zn-Y and MgZn, with the volume fraction of the second phase increasing with cumulative strain. After the extrusion treatment, the average grain size of the Mg-6Zn-1Y-0.5Zr alloy was 2.7 μm. Increasing the rolling reduction to 37% resulted in an average grain size of 5.27 μm, while a rolling reduction to 75% decreased the grain size to 4.06 μm. The Mg-6Zn-1Y-0.5Zr alloys exhibited consistent trends in ultimate tensile strength (UTS), yield strength (YS), and elongation (EL) under extrusion and various rolling strain treatments. These properties showed a relationship with cumulative strain, initially increasing and then decreasing. However, the EMI SE of the Mg-6Zn-1Y-0.5Zr alloy exhibited a positive correlation with cumulative strain. The sheets obtained through a combination of extrusion plus 37% rolling treatment exhibited excellent mechanical properties and EMI SE. The Mg-6Zn-1Y-0.5Zr alloy demonstrated UTS, YS, and EL values of 331.4 MPa, 251.3 MPa, and 18.7%, respectively. The EMI SE in the frequency range of 30–1500 MHz ranged from 79 dB to 113 dB, satisfying the requirements of the electronic information field regarding the mechanical properties and EMI SE of Mg alloy sheets.

Influence of thermo-mechanical processing on microstructure and properties of bulk metallic glassy alloys-reinforced Al matrix composites prepared by powder metallurgy

Al-matrix composites, reinforced with two different types of glassy particles and prepared by mechanical alloying, were consolidated via Spark Plasma Sintering (SPS) and hot extrusion to produce high-strength Al–5%Al65Cu20Ti15 and Al–5%Al84Ni7Co3Nb6 composites, along with pure Al sample for comparison. TEM observation and XRD analysis were used to investigate the crystal structure of the prepared powders. Metallurgical analysis tools, including SEM, TEM, XRD and EBSD, were used to investigate the effect of consolidation temperature and processing on the amorphous phase and the distribution of reinforcing particles in the composite. Also, the effect of the consolidation process on the grain morphology and size of the prepared composite was studied. Al-5% Al65Cu20Ti15 was fully densified, compared to nearly 98 % relative density for Al-5% Al84Ni7Co3Nb6 and pure Al sample prepared by hot extrusion. Moreover, Al-5% Al65Cu20Ti15 composite showed the highest hardness and ultimate tensile strength values, which are 63Hv and 226 MPa, respectively. An acceptable elongation of 15 % was also achieved. After SPS, hot extrusion process improved the strength of the composite compared with previously reported Al composites containing higher percents of Al-based glassy articles manufactured using various processing techniques. Homogenous reinforcement distribution, grain refinement and improved wettability between matrix and reinforcement are the key factors on improving the strength of Al–5%Al65Cu20Ti15 composite. The coefficient of thermal expansion (CTE) decreased by adding glassy particles to the Al-matrix, while Al-5% Al65Cu20Ti15 had the lowest values.

Microstructure and mechanical properties of 0.2C-3.9Al-1.12Mn-0.3Mo δ-TRIP steel as a function of isothermal bainitic transformation temperature

The present investigation employed a two-stage heat treatment on a δ-transformation-induced plasticity (TRIP) steel comprising 0.2C–4Al–1.2Mn–0.3Mo (wt%). The mechanical and microstructural characteristics that result from varied isothermal bainitic transformation (IBT) temperatures following inter-critical annealing at 820℃ for 10 min are thoroughly analyzed. The microstructure of the steels consisted of δ-ferrite, α-ferrite, bainitic ferrite, retained austenite (RA), and martensite, resulting in an optimum combination of the ultimate tensile strength (UTS) and total elongation (TE). The results of the investigation showed that IBT temperature had an effect on the stability of RA and the martensitic transition. Due to the increased mechanical stability of RA, the study revealed that the TRIP phenomenon was more prominent at lower IBT temperatures. Both tensile and yield strengths, as well as elongation, decreased as a consequence of the increase in IBT temperature. Maximum values of UTS, TE, and the product of these two properties (PSE) are attained (860 MPa, 41%, and 35260 MPa∙%, respectively) under optimal processing conditions (at 350℃ IBT temperature in 10 min).

Weld Line Strength of Polyamide Fiberglass Composite at Different Processing Parameters in Injection Molding Technique.

This study examines the impact of injection parameters on the weld line strength of the polyamide 6 and 30% fiberglass (PA6 + 30% FG) composite samples. The effects of filling time, packing time, packing pressure, melt temperature, and mold temperature on the ultimate tensile strength (UTS) and the elongation value of the weld line are investigated. The results reveal that the filling time factor has the lowest influence rate. On the contrary, the packing pressure has the most considerable value of UTS standard deviation, indicating that this factor has a high impact rate. The melt temperature factor has the highest elongation standard deviation, pointing out the strong impact of melt temperature on the elongation value. In reverse, the filling time factor has the lowest elongation standard deviation, showing the low impact of this factor on the elongation value. Increasing the mold temperature enhances the elongation value greatly because a higher temperature generates a better connection in the weld line area. Although the UTS value improves modestly when the mold temperature control system is used, the elongation result from the mold temperature parameter is better than expected. The UTS result from all parameters presents a minor deviation; therefore, it is lower than expected. The optimal strength result from artificial neural networks with genetic algorithm optimization is 85.1 MPa, which is higher than the best experiment result of 76.8 MPa. Scanning electron microscopy (SEM) results show that the interface between the fiberglass and the PA matrix has high adherence. The fracture surface is smooth, indicating that the PA6 + 30% FG composite sample has a high fragility level. The findings could help to increase the injection sample's weld line strength by optimizing the injection molding conditions.

Dynamic Tensile Behavior of Laser-Directed Energy Deposition and Additive Friction Stir-Deposited AerMet 100

Quasi-static and high-rate tensile experiments were used to examine the strain rate sensitivity of laser-directed energy deposition (L-DED)- and additive friction stir deposition (AFSD)-formed AerMet 100 ultrahigh-strength steel-additive manufactured builds. Electron backscattered diffraction (EBSD) revealed similar as-deposited grain sizes between the two AM processes at approximately 24 μm and 17 μm for the L-DED and AFSD samples, respectively. The strain hardening rate, θ, revealed little change in the overall hardening observed in the L-DED and AFSD materials, with a consistent hardening in the quasi-static samples and three identifiable regions in that of the high-rate tested materials. The L-DED deposited materials displayed average ultimate tensile strength values of 1835 and 2902 MPa for the 0.001 s−1 and 2500 s−1 strain rates, respectively and the AFSD deposited materials displayed ultimate tensile strength values of 1928 and 3080 MPa for the 0.001 s−1 and 2500 s−1 strain rates, respectively. Overall, the strength for both processes displayed a positive strain rate sensitivity, with increases in strength of ~1000 MPa for both processes. Fractography revealed significant solidification voids in the laser DED material and poor layer adhesion in the AFSD material.

Electronic, Thermal and Mechanical Properties of Carbon and Boron Nitride Holey Graphyne Monolayers.

In a recent experimental accomplishment, a two-dimensional holey graphyne semiconducting nanosheet with unusual annulative π-extension has been fabricated. Motivated by the aforementioned advance, herein we theoretically explore the electronic, dynamical stability, thermal and mechanical properties of carbon (C) and boron nitride (BN) holey graphyne (HGY) monolayers. Density functional theory (DFT) results reveal that while the C-HGY monolayer shows an appealing direct gap of 1.00 (0.50) eV according to the HSE06(PBE) functional, the BNHGY monolayer is an indirect insulator with large band gaps of 5.58 (4.20) eV. Furthermore, the elastic modulus (ultimate tensile strength) values of the single-layer C- and BN-HGY are predicted to be 127(41) and 105(29) GPa, respectively. The phononic and thermal properties are further investigated using machine learning interatomic potentials (MLIPs). The predicted phonon spectra confirm the dynamical stability of these novel nanoporous lattices. The room temperature lattice thermal conductivity of the considered monolayers is estimated to be very close, around 14.0 ± 1.5 W/mK. At room temperature, the C-HGY and BN-HGY monolayers are predicted to yield an ultrahigh negative thermal expansion coefficient, by more than one order of magnitude larger than that of the graphene. The presented results reveal decent stability, anomalously low elastic modulus to tensile strength ratio, ultrahigh negative thermal expansion coefficients and moderate lattice thermal conductivity of the semiconducting C-HGY and insulating BN-HGY monolayers.

Functionally graded deposition of dissimilar steel (316LSi and ER70S-6) fabricated through twin-wire arc additive manufacturing

Fabrication of dissimilar steel-based (SS316LSi over ER70S-6 steel) functionally graded deposition (FGD) using twin wire arc additive manufacturing (T-WAAM) via a unique deposition strategy is investigated in this work. Optical, SEM, EDS, X-ray diffraction (XRD), tensile, hardness, and fractography analyses were undertaken for complete microstructural and mechanical characterisation. Microstructural analysis revealed columnar, equiaxed, and cellular dendrites in δ-ferrite and austenitic phases. XRD investigation depicted the anisotropic behaviour of specimen textures in various planes. The estimated value of average ultimate tensile strength is 901 MPa, yield strength (YS) is 634 MPa, and percentage elongation (EL%) is 48 %, respectively. This work offers a novel strategy for producing superior-strength dissimilar steel components with excellent quality and varied structural utility.

Grain size dependent mechanical properties of CoCrFeMnNi high-entropy alloy investigated by shear punch testing

The effect of grain size on the mechanical properties of an equiatomic CoCrFeNiMn high-entropy alloy (HEA) was investigated by shear punch testing (SPT) as a miniature test method and Vickers hardness measurements. A Hall–Petch relationship was developed for the dependency of shear yield stress (SYS) on the average grain size (D). The correlation of the SYS and ultimate shear strength (USS) to the tensile yield stress (TYS) and ultimate tensile strength (UTS) values were also studied. A wide range of grain sizes was obtained by the thermomechanical processing of cold rolling and annealing at hot temperatures, where the primary recrystallization and grain growth phenomena were used for grain refinement and grain coarsening, respectively. Based on the obtained results and literature data, the Hall–Petch relationships of SYS = 88.9 + 301.1/√D and TYS = 167 + 520/√D were proposed, respectively. Moreover, the correlation of tensile test properties with those predicted by the shear punch test was also investigated. Accordingly, the relationships of TYS = 1.76 × SYS and UTS = 1.33 × USS were obtained, where the former is in excellent agreement with the von Mises yield criterion based on the plasticity theory, and the latter is influenced by the work-hardening behavior of the material and dynamic phenomena during plastic deformation.

Optimization on hardening process parameters of alumnium alloy 7075 based composites using gra approach

Aluminum Metal Matrix Composites (AMMCs) play a vital role in various industries, including aerospace, aviation, maritime, transportation, and automotive, owing to their remarkable mechanical strength, resistance to corrosion, and tribological performance. The age-hardening process for AA7075-based Metal Matrix Composites is essential to meet specific performance requirements, improve material properties (enhancing mechanical properties, tailoring material performance, improving wear resistance, reducing weight, enhancing corrosion resistance, extending service life), and enhancing the overall suitability of these materials for a wide range of demanding applications. The objective of this study is to improve the mechanical and tribological characteristics of AA7075-based composites by utilizing the age-hardening process, rather than introducing additional reinforcements to the base material. Aluminium Alloy 7075 (AA7075) is selected as the matrix material due to its significant need for improvement in mechanical, corrosion, and tribological properties. Nano zirconium dioxide (ZrO2) is chosen as the reinforcement to meet the property requirements of AA7075 for various applications The composites comprising AA7075 alloy and varying weight percentages of ZrO2 (x = 0, 5, 10, 15, and 20) are fabricated using the stir casting method. The fabricated composites are subjected to tensile strength and density tests to determine the optimal combination of AA7075-based composites by employing the Archimedes principle and a Universal Testing Machine, respectively. The manufactured AA7075-based composites were subjected to EDAX and SEM tests to determine the wt% presence of elements of reinforcement and matrix material by employing the S 3000 - HITACHI model. The stir-cast AA7075-based composites were further subjected to hardening under different conditions to enhance their required properties. Age hardening was performed with the help of a Muffle furnace. The input parameters for hardening were age-hardening temperature (200, 300, and 300 °C), hardening duration (90, 180, and 270 min), and cooling environments (Furnace, water, and atmosphere). The chosen response parameters were micro hardness and wear loss. The microhardness and wear resistance of these composites were assessed using a Vickers hardness tester and a Pin-on-Disc testing apparatus. The optimization was carried out using Grey Relational Analysis (GRA). The confirmation test was conducted to determine density, Ultimate Tensile Strength (UTS), micro hardness, and wear loss. The AA7075/15 wt% ZrO2 composite exhibited a uniform distribution of zirconium dioxide in the AA7075 matrix material among the other manufactured composites. The AA7075/15 wt% ZrO2 exhibited higher density of 2.889 g cm−13 and UTS of 316 MPa than other combinations of AA7075 composite materials. Increasing the heating temperature and duration enhanced the micro hardness and wear resistance. Higher micro hardness and wear resistance were obtained with furnace cooling compared to other cooling environments. The optimized age-hardening process parameters are hardening temperature (400 °C), hardening duration (270 min), and cooling environment (Furnace cooling). The enhanced mechanical and tribological properties result from precipitate formation and density enhancement. The confirmation test for the combination specimen yielded higher density, UTS, micro hardness, and lower wear loss values, which are 2.896 g/cm3, 325 MPa, 138 HV, and 27 mg, respectively.

Cracking behaviour and its suppression mechanisms with TiB2 additions in the laser additive manufacturing of solid-solution-strengthened Ni-based alloys

This study systematically investigated the cracking mechanisms in the laser powder bed fusion (LPBF) of GH3230 solid-solution-strengthened Ni-based alloy (GH0). The results show that the micro-cracks that formed in GH0 specimens included both solidification and solid-state cracks. The initiation of solidification cracks was associated with the formation of continuous liquid films on high-angle grain boundaries at the final stage of solidification, while the solid-state cracks were found to be ductility-dip cracks, associated with a reduction in the material's plasticity within the heat-affected zone. The study also found that the residual stresses decreased with increasing LSS values, leading to reductions in crack length. The introduction of 1 wt% TiB2 particles to GH3230 (GH1-composite) was found to suppress cracking by promoting grain refinement and generating special high-angle grain boundaries, although residual thermal stresses increased. The ultimate tensile strength values of the GH0 and GH1-composite specimens at 900 °C were found to be 213 and 352 MPa, respectively. These findings provide significant insights into the LPBF of high-performance crack-free Ni-based superalloys.

ANALYSING THE EFFECT OF THERMAL TREATMENT WITH AN AID OF BRINE QUENCHING ON MICROSTRUCTURAL CHARACTERISTICS AND PHYSICAL PROPERTIES OF AISI-304 PLATES

In this work, the effects of brine quenching on the mechanical properties and microstructural attributes of AISI 304 steel have been analysed. For a reference purpose, one sample was kept in ‘as-received’ condition. Three steel plates were treated at 800oC for 1 hour, 1.5 hour and 2 hours respectively. The heated samples were cooled inside brine solution up to room temperature. For mechanical property analysis, all the four plates were cut into standard sized specimens for tensile test, hardness test and toughness test. The microstructural analysis reveals that pitting corrosion has affected the γ-grains as well as δ-boundaries. The ‘as-received’ samples have shown the highest value of ultimate tensile strength (UTS) i.e., 940 MPa with 59.5% of elongation whereas the third heat treated sample, which was heated for 2 hours, has shown a decrement of 13% and 55% in UTS and elongation respectively as compared to these of ‘as received’ sample. As a result of Cr-deterioration and carbide dissolution at grain boundaries, an increase in hardness was recorded in the heat-treated samples. Also, the lowest toughness, 35% lower than as received sample, was recorded in the third sample which are heated for a long period.

The effect of the volume of tests and the number of participants on the assessment of qualification in interlaboratory comparison tests

The results of a comparative analysis of statistical indicators for assessing the proficiency determined during interlaboratory comparison tests (ICT) are presented. The main statistical indicators were selected: the assigned value, standard deviation for assessment the proficiency and standard uncertainty of the assigned value. Statistical indicators were determined in accordance with Algorithm A, GOST R 50779.60. Comparison of the indicators was carried out on the basis of numerical experiment data (random number generation) for the ultimate tensile strength of a D16AT aluminum alloy depending on the number of samples and the number of participants in the ICT qualification program. The calculation and subsequent statistical analysis of the proficiency test scores was based on the values generated by the software. Random number generation is performed for a characteristic that has a normal distribution law with the parameters of the mean equal to 450 MPa and standard deviation equal to 5 MPa. The values of the normal distribution parameters chosen as an example corresponded to the average level of tensile strength values of standard specimens made of D16AT aluminum alloy sheets. The numerical experiment (generation of random values) was carried out for given cases of the number of participants and the number of proficiency testing samples (PTS) independently of each other using separate samples of the appropriate size. A total of 36,000 ultimate tensile strength values were generated for the proficiency testing samples made of D16AT aluminum alloy sheets. As a result of calculations, 48 average values were determined (according to the number of considered implementations of ICT programs, depending on the number of participants and the proficiency testing samples) for each selected statistical indicator of the ICT qualification program. The average value of each statistical indicator was determined on samples with a bulk of 250 to 2000 generated (experimental) values, depending on the number of participants and the number of proficiency testing samples. The analysis thus performed made it possible to evaluate the influence of the volume of tests and the number of participants on the assessment of the proficiency in interlaboratory comparative tests. It is shown that for the selected range of the number of ICT participants (from 5 to 20) and the number of PTS (from 5 to 10), the value of the assigned xpt value does not depend either on the number of tested PTS or the number of ICT participants. The maximum discrepancy between the assigned value and the given level of tensile strength (450 MPa) is 0.13%, which falls within the error (rounding) for this level of values and cannot lead to significant errors in proficiency testing during ICT. The standard deviation for the qualification assessment, regardless of the number of participants, decreases with an increase in the number of proficiency testing samples, but such a decrease is insignificant and does not exceed the standard deviation (SD) value of the ultimate tensile strength (for the selected model for generating experimental values, the SD value is accepted to be 5 MPa). In contrast to the assigned value and the standard deviation for the qualification assessment, it is shown that the standard uncertainty of the assigned value for the ultimate tensile strength of standard samples made of D16AT aluminum alloy sheets depends on the number of participants and the number of proficiency testing samples tested by each participant and decreases with an increase in the number of participants in ICT programs and the number of proficiency testing samples.

The impact of welding heat input on microstructure, micro-texture, and mechanical properties of stir zone in friction stir welded DP600 steel

In this research, the impact of the heat input (HI) used during friction stir welding (FSW) on the microstructure, micro-texture and mechanical properties of DP600 steel was examined. Two different sets of rotational and transverse speeds were utilized to produce robust welds, one with low HI and the other with high. The outcomes demonstrated that various products such as polygonal ferrite (PF), Widmanstatten ferrite (WF), ferrite-carbide aggregate (FCA), and bainite were created in the stir zone (SZ) during the FSW of DP600 steel. After microscopic analysis, it was found that the high HI weld exhibited a greater amount of WF and bainite, resulting in higher hardness and ultimate tensile strength values than the low HI weld. The low HI weld displayed texture components including D1, D2, and E, with a slight cube component. These components were thought to result from the transformation of a strong B texture component and a weaker R texture component of prior austenite, indicating continious dynamic recrystallization during the FSW process. On the other hand, the high HI sample had a strong cube texture component and a weaker D shear component, a result of the transformation of a strong R shear texture component of prior austenite, suggesting discountinious dynamic recrystallization during FSW. The study determined that the welding HI greatly influences the proportion of microconstituents, the development of micro-texture, and the mechanical characteristics of the SZ during the FSW of DP600 steel.

Briquettes Optimization of Palm Shell Waste and LDPE Plastic based on Particle Size and Compressive Strength as Alternative Fuels

The purpose of this study was to find the optimal parameters of the briquette making process (particle size and pressure), where optimization was carried out based on the values of physical properties, namely density, elastic modulus and ultimate tensile strength. The method used in this study was to vary the particle size of palm shell charcoal waste with particle sizes of 40, 60, 80 and 100 mesh mixed with chopped LDPE plastic with a size of 0,5 x 0,5 cm, starch adhesive and water with a predetermined composition, then the briquettes are given varying pressures of 30N/m2, 40N/m2, 50N/m2, 60N/m2, 70N/m2 and 80N/m2. The results of this study found that the highest density value was 808,71 kg/m3, the highest elastic modulus value was 50 MPa, and the highest ultimate strength is 4,81 Mpa. Based on the values of density, elastic modulus and ultimate tensile strength, it can be concluded that the most optimal briquettes are produced from a particle size of 80 mesh and a pressure of 70N/m2 with a density value of 796,08 kg/m3, an elastic modulus of 40 MPa and an ultimate strength of 4,81 MPa.

Effect of asynchronized and synchronized laser shock peening on microstructure and mechanical properties of the Ti–6Al–4V laser joint

Welding processing is an important method to connect precision component, but the internal stress and crystal anisotropy reduce its performance, which are difficult to solve due to the specific demand on regional post-treatment. In the present research, the asynchronized laser shock peening (ALSP) and synchronized laser shock peening (SLSP) processing technologies were applied to treat the laser joined Ti–6Al–4V thin plates. The microstructure and mechanical properties of the as-welded joint, ALSP and SLSP processed joint were investigated. The results revealed that the as-welded joint presents obvious anisotropic characteristics, and high strain level exists on the prior β grain boundary, which causes stress concentration. The ultimate tensile strength (UTS) and elongation (EL) values of as-welded joint just reach the 92.18% and 72.33% of as-received plate, respectively. ALSP processing could result in the deformation with the depth more than ten microns and introduce compress stress in the top layer, but has little effect on decreasing the anisotropy. The grain boundary becomes obscure and the strain distribution is relatively uniform, accompanying with some dynamic recrystallized laths exist along the grain boundary. Its values of UTS and EL are 5.23% and 5.59% higher than as-welded joint, respectively. With the SLSP processing, the deformation depth exceeds twenty microns, and the crystal isotropy could be greatly promoted. Moreover, higher compressive stress is introduced from top layer to center area of joint. The grain boundary becomes obviously obscure, which is completely replaced by recrystallized lath structures. The residual strain in the top layer is partly eliminated, and the stress concentration phenomenon along grain boundary is dramatically decreased. The UTS and EL values are 6.16% and 20.58% higher than as-welded joint, and reach 97.86% and 87.22% of as-received plate, respectively.