Tensile Elongation Values Research Articles

Mechanical Properties of PVA/Alginate Membranes Fabricated using Electrospinning as A Wound Dressing

Alginate is an interesting natural biopolymer due to its many benefits and good biological properties. Observing the mechanical properties of PVA/Alginate fibers made by electrospinning machines can help predict their behavior and measure their performance under various conditions including applied external forces. Therefore, this study investigated the elastic properties of PVA/Alginate membranes, specifically tensile strength and elongation. The fabrication material used is PVA / Alginate solution with a PVA solution concentration of 20% and alginate solution 2.5%. The electrospinning process is carried out by optimizing at a voltage of 25 kV, the distance between the spinneret end and the collector is 15 cm, the flow rate is 130, and the spinneret diameter variations are 0.4 mm, 0.6 mm, and 0.8 mm. To determine the morphology of the fiber surface, observations were made using ocular microscopes and SEM. From this observation, it is known that the morphology formed using a 0.4 mm spinneret has the tightest structure among the three sizes of spinneret diameter. To determine the effect of spinneret diameter on the value of tensile strength and elongation, tensile strength tests are carried out. The tensile strength and elongation values of the membrane obtained with variations in spinneret diameters of 0.4 mm, 0.6 mm, and 0.8 mm are 1.96 MPa, 3.77 MPa and 6.11 MPa respectively and the elongation values are 17%, 52.7%, and 97%. With medical material standards, it has a tensile strength value between 1 MPa – 24 MPa and an elongation value between 17% – 207%, so that PVA / Alginate fiber membranes have the potential to be applied as wound dressings.

Dissimilar MIG Welding Optimization of C20 and SUS201 by Taguchi Method

This study looks at how welding intensity, speed, voltage, and stick-out affect the structural and mechanical characteristics of metal inert gas (MIG) welding on SUS 201 stainless steel and C20 steel. The Taguchi method is used to optimize the study’s experiment findings. The results show that the welding current has a more significant effect on the tensile test than the welding voltage, stick-out, and welding speed. Welding voltage has the lowest influence. In addition to the base metals’ ferrite, pearlite, and austenite phases, the weld bead area contains martensite and bainite microstructures. The optimal parameters for the ultimate tensile strength (UTS), yield strength, and elongation values are a 110 amp welding current, 15 V of voltage, a 500 mm.min−1 welding speed, and a 10 mm stick-out. The confirmed UTS, yield strength, and elongation values are 452.78 MPa, 374.65 MPa, and 38.55%, respectively, comparable with the expected value derived using the Taguchi method. In the flexural test, the welding current is the most critical element affecting flexural strength. A welding current of 110 amp, an arc voltage of 15 V, a welding speed of 500 mm.min−1, and a stick-out of 12 mm are the ideal values for flexural strength. The flexural strength, confirmed at 1756.78 MPa, is more than that of the other samples. The study’s conclusions can offer more details regarding the dissimilar welding industry.

Elimination of cracks in Al–Zn–Mg–Cu alloy by addition of TiO2 in selective laser melting

7050 aluminium alloy is widely used in aerospace industry due to its excellent mechanical properties. 7050 aluminium alloy belongs to Al–Zn–Mg–Cu alloy. Due to the formation of cracks in selective laser melting (SLM) forming of Al–Zn–Mg–Cu alloys, 7050 aluminium alloy is difficult to be applied to forming and manufacturing in this technological field. In order to solve this critical problem, in this paper, titanium dioxide (TiO2) powder was mixed with 7050 aluminium alloy using ball milling method to achieve the effect of eliminating cracks. The cracks in the specimens completely disappeared when the TiO2 additions were 1.5 wt% and 2 wt%. With the addition of TiO2, the grains gradually changed from coarse columnar crystals to fine equiaxed crystals. Combined with the temperature field simulation, the grain refinement and crack elimination mechanism of TiO2 in SLM forming were analysed. The grain refinement is attributed to the formation of Al3Ti. The crack elimination was attributed to the reduction of the intergranular solid-liquid channel length. The maximum values of tensile strength and elongation of 7050 aluminium alloy formed by SLM are achieved at 2 wt% of TiO2. The values are 389 MPa and 8.8 %. The better mechanical properties were attributed to the synergistic effect of crack elimination, Hall-Petch, and Orowan strengthening. This study provides experimental guidance for the preparation of crack-free 7050 aluminium alloy.

Experimental study of shielding gas concentration on mechanical properties of stainless steel alloy parts using wire and arc additive manufacturing

Wire Arc Additive Manufacturing (WAAM) is an emerging three-dimensional fabrication technology that enables higher deposition rate, material savings, and near net-shape. In this study, various shielding gas concentration (SGC) of argon (Ar) and carbon-di-oxide (CO2) was employed to fabricate 316L using Cold Metal Transfer (CMT) WAAM process. Microstructure characteristics and mechanical properties of thick-walled parts were studied. Microstructure studies show a combination of columnar and equiaxed grains in various regions. Microhardness results exhibit the uneven distribution of hardness value from bottom to top region along the building direction and the values are ranging between185 and 240 HV. Tensile studies indicates the both horizontal and vertical direction samples secures the higher ultimate tensile strength (UTS), yield strength (YS) and elongation (EL) values and confirmed the isotropic properties. Fractography studies prove ductile fracture with the evidence of dimples and enough plastic deformation. From the experimental results, the SGC-2 possesses finer solidification structure and higher mechanical properties than the other samples. The as-fabricated WAAM parts possess higher mechanical properties than the 316L parts fabricated via casting and wrought parts.

Effect of intermetallic compounds on the mechanical properties of Cu/Al clad sheets with an SS304 interlayer

Annealing treatments were conducted on Cu/Al clad sheets incorporating a 304 stainless steel (SS304) interlayer to investigate the impact of intermetallic compounds (IMCs) on the mechanical properties of these clad sheets with an interfacial layer. Additionally, the mechanisms of interfacial strengthening and crack propagation behavior were examined. It was found that the best overall performance was achieved for samples annealed at 200 °C, showing tensile strength, fracture elongation, and peeling strength values of 219 MPa, 7.19 %, and 19.6 N/mm, respectively. For the rolled clad sheet, cracks typically initiated at the edges of the SS304 fragments, accompanied by minor residual holes and stress concentrations. Post-annealing, the Cu and Al layers underwent varying degrees of recovery and recrystallization, and element diffusion increased, leading to improvements in elongation and interfacial bonding strength of the clad sheets. As the thickness of the IMCs grew, the interfacial crack propagation path shifted to the Al2Cu/AlCu interface within the IMC layer, significantly reducing the bonding strength.

Composite cellulose/bismuth/PVA nanocrystal for high-performance X-ray radiation shielding

The strong penetrating power of X-rays causes serious health problems. Longer exposure to radiation that penetrates normal cells can result in gene mutations, cancer, and even death. Protection against radiation exposure is necessary to prevent negative impacts from occurring. This research aims to make apron samples using a simple method based on cellulose as a matrix, bismuth as a filler with concentrations of 1 g, 0.75 g, 0.25 g and PVA acts as a binder that helps bind cellulose and bismuth particles into an effective X-ray radiation shield. The characterization carried out includes Fourier transform infrared (FTIR) to determine the functional groups and chemical composition of the sample, x-ray diffraction (XRD) to analyze the crystal size of the sample, and mobile x-ray with energies of 60, 70, and 80 keV to determine the radiation shielding performance. The findings of this study highlight that the optimal shielding properties were attained by employing a sample with the highest concentration of bismuth filler, specifically at 1 g. This material exhibits outstanding characteristics, including a high linear attenuation coefficient and mass attenuation coefficient of 0.68 cm−1 and 2.24 cm2/g respectively for an energy of 60 keV and especially low HVL (1.01 cm) and TVL (3.36 cm) values. These findings have significant implications for developing high-performance X-ray radiation shielding materials, particularly in industries where radiation exposure is a concern, such as the medical industry, research, and laboratories. The high tensile strength (2.83 N/mm2) and elongation (12.09 %) values as well as the low Young's modulus (0.108 N/mm2) values also indicate the flexibility of the resulting material, which could be beneficial for applications that require flexible shielding materials. The practicality of this research makes the audience feel that the findings are applicable and useful in real-world scenarios.

Study on barrier properties, biodegradability and antimicrobial activity of linear low density polyethylene/starch blends

Purpose The present work aims to prepare biocomposites blend based on linear low density polyethylene/ starch without using harmful chemicals to improve the adhesion between two phases. Also, the efficiency of essential oils as green plasticizers and natural antimicrobial agents were evaluated. Design/methodology/approach Barrier properties and biodegradation behavior of linear low density polyethylene/starch (LLDPE/starch) blends plasticized with different essential oils including moringa oleifera and castor oils wereassessed as a comparison with traditional plasticizer such as glycerol. Biodegradation behavior forLLDPE/starch blends was monitored by soil burial test. The composted samples were recovered then washed followed by drying, and weighting samples after 30, 60, and 90 days to assess the change in weight loss. Also, mechanical properties including retention values of tensile strength and elongation at break were measured before and after composting. Furthermore, scanning electron microscope (SEM) was used to evaluate the change in the morphology of the polymeric blends. In addition to, the antimicrobial activity of plasticized LLDPE/starch blends films was evaluated using a standard plate counting technique. Findings The results illustrate that the water vapor transition rate increases from 2.5 g m−2 24 h−1 for LLDPE/5starch to 4.21 g m−2 24 h−1 and 4.43 g m−2 24 h−1 for castor and moringa oleifera respectively. Also, the retained tensile strength values of all blends decrease gradually with increasing composting period. Unplasticized LLDPE/5starch showed highest tensile strength retention of 91.6% compared to the other blends that were 89.61, 88.49 and 86.91 for the plasticized LLDPE/5starch with glycerol, castor and M. oleifera oils respectively. As well as, the presence of essential oils in LLDPE/ starch blends increase the inhibition growth of escherichia coli, candida albicans and staphylococcus aureus. Originality/value The objective of this work is to develop cost-effective and environmentally-friendly methods for preparing biodegradable polymers suitable for packaging applications.

Effects of Zr and Y additions on microstructure and mechanical properties of cast A356 alloy

In the present work, the effects of Zr and/or Y addition on microstructure and mechanical properties of cast A356 alloy were investigated using X-ray diffractometer (XRD), differential scanning calorimetry (DSC), optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The heterogeneous nucleation effect on Zr-rich phases generated by the peritectic reaction, the increased constitutional undercooling caused by Y addition and serve as surfactant led to the grain refinement. Besides, The average size of eutectic Si reduced from 8.5 μm in the base alloy to 6.2, 1.3, and 1.7 μm with the addition of Zr/Y/Zr + Y, respectively. Zr can slightly refine eutectic Si due to the limited growth space caused by grain refinement, while Y can modify the morphology of eutectic Si from plate-like into fibrous-like through high density twins formed by the IIT mechanism. The optimal mechanical properties are obtained when Zr and Y are added simultaneously with the ultimate tensile strength, yield strength, and elongation values of 104 MPa, 201 MPa, and 7.6%, respectively. The YS and UTS increase was due to grain-refining, Si modification and precipitation strengthening. The enhancement of El was mainly caused by Si modification, which reduced the possibility of crack initiation and propagation at Si/α-Al interfaces.

Hybrid interlayer hot rolling and wire arc additive manufacturing of Al-Mg alloy: Microstructure, mechanical properties and strengthening mechanism

Considering the deformation-strengthening benefits of Al-Mg alloy and the high forming efficiency offered by wire and arc additive manufacturing (WAAM), the microstructure evolution and strengthening mechanism of hybrid interlayer hot rolling and wire arc additive manufacturing (HR-WAAM) samples have been systematically investigated in this study. The results indicate that interlayer hot rolling can effectively reduce the size and number of pores, which diminishes the stress concentration areas. Additionally, rolling deformation significantly enhances the effect of dislocation strengthening. Furthermore, a high density of dislocations can promote recrystallization to refine grain size, while also improving grain orientation, all of which contribute to better stress distribution. Due to these reasons, the strength and toughness of the alloy are notably improved. The average ultimate tensile strength (UTS), yield strength (YS), and elongation (EL) values achieved by HR-WAAM samples were 338 MPa, 276 MPa, and 20.9%, respectively. These values represent increases of 28.5%, 41.5%, and 38.4% compared to conventional WAAM samples. These findings are expected to provide an efficient and cost-effective method for additive manufacturing (AM) of deformation-strengthened aluminum alloys.

Segregation-induced abnormal recrystallization behavior, texture evolution, and effects on mechanical properties in twin-roll casting 2060 Al-Cu-Li alloys

Twin-roll casting (TRC) faces persistent segregation challenges limiting widespread use., Leveraging a comprehensive suite of techniques—electron probe microanalyzer (EPMA), electron back-scattered diffraction (EBSD), and transmission electron microscope (TEM)—and rooted in a thermo-mechanical-solute integrative simulation, this study focus on a detailed exposition of the structural evolution of the 2060 Al-Cu-Li alloy, encompassing its segregation tendencies and textural transformations throughout its processing trajectory. High and low-stress TRC scenarios, TRC-3 and TRC-6, are explored. Empirical observations ascertained that the TRC venture, particularly in TRC-3, cultivates a pronounced segregation gradient, a direct offshoot of the stress gradient, thereby inducing textural disparities. During the homogenization phase, the TRC structure with diminished segregation (TRC-6) manifested signs of recovery and sustained recrystallization, an environment amiable to compositional homogeneity and tempering the pre-existing segregation. In the terminal state, a pioneering discovery elucidated that heightened segregation precipitated the β-fiber textural enhancement mechanism—a phenomenon that deteriorates properties due to the discrepancy in segregation-induced hardness. With astutely managed segregation, TRC-6 recorded tensile strengths and elongation values of 563 MPa and 7.1% respectively, marking an increment by 20.0% and 208.7% in comparison to TRC-3. This research offers vital insights into solute gradients, providing a new perspective on gradient materials.

Manufacturing profiled conical cylinder by a semi-closed isothermal precision die forging technology

An improved semi-closed isothermal precision dies forging process has been used to produce successfully precision profiled conical cylinder forging. The semi-closed die forging significantly improved the forming quality and deformation homogeneity of profiled forgings, and greatly reduced die forging force by isothermal forging with three-stage variable speed. The static recrystallization during solution process was inhibited, and fine and even dynamic recrystallized grains and abundant sub-grains were obtained. In addition, the difference of the microstructure at each position was small and the distribution of grains and second phase particles was uniform. This significantly improved the mechanical properties and homogeneity of forgings, and the average values of tensile strength, yield strength and elongation reached 480.9 MPa, 387.8 MPa and 8.75%, respectively.

Movement Strategy Influences on the Characteristics of Low-Carbon Steel Generated by the Lamination Object Manufacturing Method

This paper investigates the effects of heating movement techniques on the properties of low-carbon steel samples that are 3D printed using S20C lamination object manufacturing (LOM). A Tungsten iner gas (TIG) machine and a computer numerical control (CNC) machine were used together to join the steel sheet. The LOM samples were created with a straight-profile, short-profile, cross-profile, and curved-profile. The results indicate that the majority of the samples had a grain size number of 7–9. The samples exhibited an isotropy grain shape. The LOM samples exhibited dimples, which suggests ductility fractures. Pore flaws showed up in the microstructure of the cross-profile and short-profile samples during the LOM process. The samples with curved- and straight-profiles had a better microstructure. In comparison to samples with a short profile and a cross-profile, the samples with a straight-profile and a curved-profile had a superior combination of ultimate tensile strengths (UTSs) and elongation value. The straight- and curved-profiles’ greater elongation and tensile strength can be attributed to their improved microstructure and finer grain size. A straight-profile sample with an elongation value of 25.6% and a UTS value of 430 MPa was the ideal LOM sample. Conversely, the weakest sample was the LOM sample with a cross-profile, which had an elongation value of 10.8% and a UTS value of 332.5 MPa. This research could provide further information about the LOM method and the best straight-profile movement strategy. A suitable TIG gun movement strategy could produce a good LOM sample with a good microstructure, tensile strength, and ductility. Further research should incorporate more movement strategies and techniques that completely prevent the formation of pore defects.

Effects of Process Parameters in Thermoforming of Unidirectional Fibre-Reinforced Thermoplastics.

Process-induced defects during thermoforming are widespread problems in laminate manufacturing. The aim of this study is to describe the effects of holding time and pressure on several properties of the manufactured laminate. A design of experiments is performed, followed by an analysis of variance to examine significant effects. Subsequently, a regression model is created to predict the laminate's properties, which is also validated. A significant interaction between holding time and pressure is determined for the resulting tensile strength and elongation at break with a p-value of 1.52·10-16 and 0.02, respectively. The highest values of tensile strength and elongation at break are found for low settings of holding time and pressure. The fibre volume fraction is not affected by the process parameters. As holding time and pressure increase, significant fibre misalignment takes place, leading to a decrease of the mechanical properties. The regression model corresponds well with the validation and a tensile strength of 1049 MPa with an elongation at break of 2.3% is reached.

Effect of Vanadium Addition on Solidification Microstructure and Mechanical Properties of Al-4Ni Alloy.

The effects of vanadium addition on the solidification microstructure and mechanical properties of Al-4Ni alloy were investigated via thermodynamic computation, thermal analysis, microstructural observations, and mechanical properties testing. The results show that the nucleation temperature of primary α-Al increased with increased vanadium addition. A transition from columnar to equiaxed growth took place when adding vanadium to Al-4Ni alloys, and the average grain size of primary α-Al was reduced from 1105 μm to 252 μm. When the vanadium addition was 0.2 wt%, the eutectic nucleation temperature increased from 636.2 °C for the Al-4Ni alloy to 640.5 °C, and the eutectic solidification time decreased from 310 s to 282 s. The average diameter of the eutectic Al3Ni phases in the Al-4Ni-0.2V alloy reduced to 0.14 μm from 0.26 μm for the Al-4Ni alloy. As the vanadium additions exceeded 0.2 wt%, the eutectic nucleation temperature had no obvious change and the eutectic solidification time increased. The eutectic Al3Ni phases began to coarsen, and the number of lamellar eutectic boundaries increased. The mechanical properties of Al-4Ni alloys gradually increased with vanadium addition (0-0.4 wt%). The Al-4Ni-0.4V alloy obtained the maximum tensile strength and elongation values, which were 136.4 MPa and 23.5%, respectively. As the vanadium addition exceeded 0.4 wt%, the strength and elongation decreased, while the hardness continued to increase. Fracture in the Al-4Ni-0.4V alloy exhibited ductile fracture, while fracture in the Al-4Ni-0.6V alloy was composed of dimples, tear edges, and cleavage planes, demonstrating mixed ductile-brittle fracture. The cleavage planes were caused by the primary Al10V and coarse Al3Ni phases at the boundary of eutectic cells.

External gas-assisted mold temperature control and optimization molding parameters for improving weld line strength in polyamide plastics.

In this study, we present a novel approach to injection molding, focusing on the strength of weld lines in polyamide 6 (PA6) composite samples. By implementing a mold temperature significantly higher than the typical molding practice, which rarely exceeds 100°C, we assess the effects of advanced mold temperature management. The research introduces a newly engineered mold structure specifically designed for localized mold heating, distinguishing it as the 'novel cavity.' This innovative design is compared against traditional molding methods to highlight the improvements in weld line strength at elevated mold temperatures. To optimize the molding parameters, we apply an Artificial Neural Network (ANN) in conjunction with a Genetic Algorithm (GA). Our findings reveal that the optimal ultimate tensile strength (UTS) and elongation values are achieved with a filling time of 3.4 seconds, packing time of 0.8 seconds, melt temperature of 246°C, and a novel high mold temperature of 173°C. A specific sample demonstrated the best molding parameters at a filling time of 3.4 seconds, packing time of 0.4 seconds, melt temperature of 244°C, and mold temperature of 173°C, resulting in an elongation value of 582.6% and a UTS of 62.3 MPa. The most influential factor on the PA6 sample's UTS and elongation at the weld line was found to be the melt temperature, while the filling time had the least impact. SEM analysis of the fracture surfaces revealed ductile fractures with rough surfaces and grooves, indicative of the weld line areas' bonding quality. These insights pave the way for significant improvements in injection molding conditions, potentially revolutionizing the manufacturing process by enhancing the structural integrity of the weld lines in molded PA6 samples.

BAZI MEKANIKSEL DERI VE TEKSTIL STANDART METOTLARININ UYGULAMALI OLARAK KARŞILAŞTIRILMASI

Fabrics, leathers and artificial materials show structurally different properties. For example, if a fabric material is woven, it is formed by connecting the threads at a right angle to each other with a certain system; on the other hand, leather is formed by naturally binding complex collagen fibers with specific and different angles depending on their area. Also, artificial materials are produced disparately using PVC and PU. These structural differences directly affect the mechanical properties of materials and therefore Turkish Standards Institute (TSE) offers different test methods for textile and leather materials. There are some differences between these standards according to the shape/size of test samples, jaw length, speed, etc. Since leather is an expensive material and has a limited area, sample sizes of leather standards are smaller than the dimensions specified in the textile standard; however, sample sizes in textile standards can be a problem for some expensive textile materials e.g., silk, silver-added fabrics, vicuna, etc. The aim of this study is to examine the differences between the results obtained from the textile and leather standard methods. In this scope, the tensile strength, elongation and tear load values of the two different tanned garment leathers, artificial material, and two different kinds of woven fabrics were obtained by applying both leather and textile standard methods. While there was a statistical difference between the two methods in tensile strength and elongation values for all materials, no difference was observed in tear load values.

Investigation on the Attainment of High-Density 316L Stainless Steel with Selective Laser Sintering.

Due to the low density of the green part produced by selective laser sintering (SLS), previous reports mainly improve the sample's density through the infiltration of low-melting metals or using isostatic pressing technology. In this study, the feasibility of preparing high-density 316L stainless steel using 316L and epoxy resin E-12 as raw materials for SLS combined with debinding and sintering was investigated. The results indicated that in an argon atmosphere, high carbon and oxygen contents, along with the uneven distribution of oxygen, led to the formation of impurity phases such as metal oxides, including Cr2O3 and FeO, preventing the effective densification of the sintered samples. Hydrogen-sintered samples can achieve a high relative density exceeding 98% without losing their original design shape. This can be attributed to hydrogen's strong reducibility (effectively reducing the carbon and oxygen contents in the samples, improving their distribution uniformity, and eliminating impurity phases) and hydrogen's higher thermal conductivity (about 10 times that of argon, reducing temperature gradients in the sintered samples and promoting better sintering). The microstructure of the hydrogen-sintered samples consisted of equiaxed austenite and ferrite phases. The samples exhibited the highest values of tensile strength, yield strength, and elongation at 1440 °C, reaching 513.5 MPa, 187.4 MPa, and 76.1%, respectively.

A novel film based on a cellulose/sodium alginate/gelatin composite activated with an ethanolic fraction of Boswellia sacra oleo gum resin.

Boswellia sacra and its derivatives exhibit notable bioactive properties, which have been the subject of extensive scientific research; however, their potential applications in food packaging remain largely untapped. In the current study, cellulose, sodium alginate, and gelatin composite edible films were fabricated with the addition of different concentrations (0.2% and 0.3%) of the ethanolic fraction of Boswellia sacra oleo gum resin (BSOR). The resultant films were examined for their physical, chemical, mechanical, barrier, optical, and antioxidant properties. Moreover, the films were characterized using Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) to study the impact of incorporating BSOR on the morphological, crystalline, and chemical properties of the films. The addition of BSOR increased the film thickness (0.026-0.08 mm), water vapor permeability (0.210-0.619 (g.mm)/(m2.h.kPa), and the intensity of the yellow color (3.01-7.20) while reducing the values of both tensile strength (6.67-1.03 MPa) and elongation at break (83.50%-48.81%). SEM and FTIR analysis confirmed the interaction between the BSOR and film-forming components. The antioxidant properties of the edible films were significantly increased with the addition of BSOR. The comprehensive findings of the study demonstrated that BSOR possesses the potential to serve as an efficient natural antioxidant agent in the fabrication of edible films.

Synthesis and Characterization of Biodegradable Plastic from Tropical Marine Microalgae Navicula sp. TAD01

The use of plastics made from petrochemicals has a bad environmental impact. One of the efforts to overcome this is using microalgae Navicula sp. as a raw material for making biodegradable plastics. Navicula sp. TAD01 is a type of marine microalgae that is spread Inner Bay of Ambon and can be used to manufacture biodegradable plastics. In this study, biodegradable plastic was synthesized from the biomass of Navicula sp. TAD01, characterization and degradation test. The method used in this research includes three stages. Navicula sp. TAD01 cells were grown in the first stage to obtain biomass. The second stage is making biodegradable plastic from the biomass of Navicula sp. TAD01. The last step is to characterize biodegradable plastics and perform a degradation test. Cultivation of Navicula sp. TAD01 obtained dry biomass of 6.4398 grams, with a productivity value of 0.0524 gL-1h-1. The biodegradable plastic made has a slippery texture and a greenish opaque color with a thickness of 0.05 mm. It has tensile strength and elongation values at break of 1.36 MPa and 30.7%, respectively. The results of the analysis of the biodegradation test on this biodegradable plastic film have a mass loss percentage value of 85.27% with an immersion time of 10 days. This shows that Navicula sp TAD01 has the potential to be used as an ingredient in the manufacture of biodegradable plastics that can degrade well

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.