Tensile Impact Strength Research Articles

The effect of Ti alloying on the mechanical properties and microstructure of a Zn–Al–Cu–Mg alloy

Abstract The effect of Ti additions (0.01 – 0.20 wt.%) on the hardness, ultimate tensile strength, impact strength and creep properties of the gravity-cast Zn–Al –Cu–Mg alloy ZA-8 has been investigated. The Ti additions have no significant effect on the hardness. The ultimate tensile strength of the standard ZA-8 alloy has not been changed significantly with Ti additions up to 0.15 wt.% and then decreased with further increase in Ti content. The impact strength shows a maximum around 0.05 – 0.15 wt.% Ti. The lowest creep resistance is obtained at 0.01 wt.% Ti, and the highest value of creep resistance is reached for 0.20 wt.% Ti. Metallographic studies indicated that the addition of Ti has a profound effect on the microstructure. Also, Ti forms a complex-shaped intermetallic compound which was identified as TiZn15 by X-ray diffraction. It is suggested that the TiZn15 particles cause the increase in creep resistance and decrease in tensile strength.

Deterioration of Property of Aluminum Alloys (EN AW-1050A, EN AW-5754 and EN AW-6060) by Absorbed Hydrogen

The paper reports the results of research on the effect of hydrogen penetration on the variations in the mechanical properties of selected aluminum alloys. As a result of the study, it can be observed that such variations contribute to the deterioration of mechanical properties, which, in turn, contributes to shortening the reliability time associated with the operation of aluminum alloy structures. The analysis involved structural aluminum alloys: EN AW-1050A, EN AW-5754 and EN AW-6060. Tensile strength and impact strength were measured. It was demonstrated that the absorption of hydrogen by the analyzed alloys led to the deterioration of mechanical properties of aluminum alloys. The performed measurements were compared to the previous research results regarding the influence of hydrogen on the deterioration of corrosion properties. The analysis of the influence of hydrogen on both issues allowed us to notice the reasons for shortening the operational reliability time of aluminum alloy parts. The awareness of the influence of hydrogen on aluminum alloys may contribute to the development of hydrogen systems or installations in which aluminum alloys can be used as a construction material, e.g., fuel cells, hydrogen supply pipes, block of combustion engine powered by hydrogen, etc. In the era of the development of zero-emission vehicles, the use of hydrogen as fuel is gaining more and more importance, where the influence of hydrogen on the properties of materials is an important issue.

Mproving the properties of steels by producing in their structure along with other components of metastable austenite and the following hardening

The relevance. Improving the mechanical properties of steels and their wear resistance makes it possible to increase the service life of machine parts, which is an important task of materials science. One of the promising directions in its solution is combined processing technologies of steels based on the principle of obtaining in them in various ways a structure containing, along with other components (various types of martensite, lower bainite, in some cases carbides) of an increased amount (³ 25 %) of metastable austenite, and subsequent strengthening. In this case, a certain amount of austenite transforms into deformation martensite, and the its remaining part undergoes dynamic deformation martensitic transformation (DDMT) – the effect of self-hardening under loading (SHL). Combined processing technologies include thermal (in some cases, chemical-thermal) and deformation effects on the metal, carried out in various combinations and sequences. Processing technologies for obtaining an increased amount of metastable austenite in the structure of steels can include: holding in the intercritical temperature interval (ICTI) with various hardening methods, plastic deformation stabilizing austenite with respect to the formation of cooling martensite, thermal cycling, etc. Strengthening of steels with an increased amount of metastable austenite is carried out by cold plastic deformation, after which tempering is carried out in some cases. However, the principle is currently being considered and the combined processing technologies that implement it are not used in industry. This excludes the use of metastable austenite, which is an internal resource of the material itself, and its transformation under loading, which increases its ability to self-defense against destruction during testing of properties and operation. In this regard, it is advisable to introduce the proposed combined processing technologies into practice, which will ensure resource saving. In work on a number of steels their effectiveness has been shown.
 Рurpose is to show the possibility of increasing the mechanical properties or wear resistance of the studied steels by using combined processing technologies based on the principle that provides for the production of an increased amount of metastable austenite in their structure and subsequent hardening, which preserves the possibility of DDMT and the implementation of the effect SHL.
 Research methods. Durometric, metallographic and X-ray research methods were used. The tensile properties and impact strength, as well as abrasive wear resistance, were determined. These properties were compared with those obtained for the studied steels after a typical heat treatment.
 Results. It is shown that the proposed combined treatment technologies, including the production of an increased amount of metastable austenite in the structure of the studied steels and subsequent hardening, which retains the possibility of DDMT and the implementation of the effect SHL, increase the mechanical properties or wear resistance in comparison with their level after the commonly used treatment.
 Scientific novelty. To improve the mechanical properties or wear resistance of alloys an innovative principle was proposed, which consists in obtaining in them an increased amount of metastable austenite before strengthening treatments, preserving after them a part of it that can undergo DDMT and, accordingly, realize the effect SHL when testing properties and operation.
 Practical value. For the studied steels, rational modes of combined processing technologies have been determined, including obtaining an increased amount of metastable austenite in their structure and subsequent hardening, which have shown their effectiveness in increasing mechanical properties or wear resistance in comparison with commonly used treatments.

Analysis of mechanical strength of weight fraction variation sugar palm fiber as polypropylene-elastomer matrix reinforcement of hybrid composite

Currently, the availability of polypropylene, elastomer and sugar palm fiber (Arenga pinnata) is very abundant, which has a good impact on the potential for the development of new composite materials that have good properties and characteristics. Composites are generally a new material composed of two or more different materials with the aim of producing a new material that has better properties than the constituent material. In this study, polypropylene (PP) plastic and elastomer were used as a composite matrix reinforced with sugar palm fiber (Arenga pinnata). The purpose of this study was to determine the value of tensile strength, impact strength, and bending strength of composites with a weight fraction of 20 % (80:20), 30 % (70:30), and 40 % (60:40). Based on the results of the research on hybrid composites of polypropylene and fiber-reinforced elastomers, composites with a weight fraction of 20 % (80:20) got the lowest tensile strength value of 1.153 MPa, while composites with a weight fraction of 40 % (60:40) obtained the highest tensile strength value of 2.613 MPa. Composites with a weight fraction of 20 % (80:20) got the lowest tensile strain value of 0.0049 and the highest tensile strain value of 0.0067 was found in composites with a weight fraction of 40 % (60:40). For the impact strength, the 40 % (40:60) weight fraction composite got the lowest value of 45248.234 kJ/mm2, while the 20 % (80:20) weight fraction composite got the highest impact strength of 17649.97 kJ/mm2. For bending strength results, the composite with a weight fraction of 20 % (80:20) obtained the lowest bending strength of 1.7778 MPa, while the composite with a weight fraction of 30 % (70:30) obtained the highest bending strength of 4.8867 MPa. The highest bending strain was found in the composite with a weight fraction of 20 % (80:20), which was 0.0207.

Experimental investigation and optimization of quality characteristics during friction stir welding of Al- and Zn-based magnesium alloy using artificial intelligence

Friction stir welding is successfully used to weld different wrought magnesium alloys. This work investigated the mechanical and microstructural behavior of the friction stir-welded AZ31B magnesium alloy. The experiments were conducted as per experimental runs designed by response surface methodology. An artificial neural network model was developed to produce a relationship between process variables (tool rotational speed, welding speed, and tool shoulder diameter) and characteristics of the friction stir-welded joints (tensile strength, percentage elongation, impact strength, microhardness, and grain size). The acceptable range of statistical parameters validated the adequacy of the model. The multi-objective optimization technique, genetic algorithm was used to obtain a set of Pareto optimal solutions. The best-compromised optimum solution for maximum tensile strength (164.2 MPa), percentage elongation (8%) impact strength (3.5 J), microhardness (85 Hv), and minimum grain size (13.1 μm) was validated by confirmation test with <3 percent absolute error percentage. The fractographical analysis has been performed and dimples and torn edges observed in fracture zones.

Design of hybrid PLA/PBS/POM composite based on In-Situ formation of interpenetrating fiber networks

Hybrid polymer–polymer nanocomposite of polylactide/poly(1,4-butylene succinate)/ polyoxymethylene (PLA/PBS/POM) system with interpenetrating fiber network was manufactured. Hybridization was by combining tough, in situ generated PBS nanofibers with rigid, ready-made electrospun POM nanofibers. The concentration of PBS and POM components was 10 wt% to establish continuous fiber network. Nanoporous surface of POM nanofibers with high specific surface area enabled strong interfacial interaction with PLA matrix. A positive effect of hybridization on mechanical properties was achieved for composite with interpenetrating network of POM and PBS fibers. Compared to PLA/PBS/POM blend, the PLA/PBS/POM composite was characterized by increase in: elastic modulus, yield stress, tensile impact strength and strain at break. Presence of POM fibers caused increase: in crystallinity and in crystallization temperature of PBS due to shear-induced crystallization. Presence of PBS and POM nanofibers caused a change of plastic deformation of PLA matrix from heterogeneous intensive crazing to homogeneous.

Microstructure Effect of Heat Input on Ballistic Performance of Welded High Strength Armor Steel

The effect of two different heat inputs, 1.2 and 0.8 kJ/ mg, on the microstructure associated with a welded high hardness armor (HHA) steel was investigated by ballistic tests. A novel way of comparing the ballistic performance between fusion zone (FZ), heat-affected zone (HAZ), and base metal (BM) of the HHA joint plate was applied by using results of the limit velocity V50. These results of V50 were combined with those of ballistic absorbed impact energy, microhardness, and Charpy and tensile strength revealing that the higher ballistic performance was attained for the lower heat input. Indeed, the lower heat input was associated with a superior performance of the HAZ, by reaching a V50 projectile limit velocity of 668 m/s, as compared to V50 of 622 m/s for higher heat input as well as to both FZ and BM, with 556 and 567 m/s, respectively. Another relevant result, which is for the first time disclosed, refers to the comparative lower microhardness of the HAZ (445 HV) vs. BM (503 HV), in spite of the HAZ superior ballistic performance. This apparent contradiction is attributed to the HAZ bainitic microstructure with a relatively greater toughness, which was found more determinant for the ballistic resistance than the harder microstructure of the BM tempered martensite.

Investigating the Mechanical Behavior of 3D Printed PLA-Coco Coir Composites

It is quite amazing that the use of 3D printing techniques, especially the Fused Deposition Modelling (FDM) has delivered such significance in terms of cost reduction, time saver features where a different variety of thermoplastic and composite materials (Biodegradable and Non-biodegradable) are well developed. Different sectors have continually developed natural organic materials that are also both structurally composite in nature. Similarly, the use of different fibers that are abundantly accessible and considered as renewable resources which can be optionally combined with other biodegradable materials is a great challenge through the use of the FDM printing method. The study aims to determine the effect of different particle size and raster angle at a certain fiber concentration which could affect the mechanical properties of the composite by developing a printable composite filament made of Polylactic Acid (PLA) and Coco Coir materials using a filament maker and FDM printer. The composite filament was fabricated and optimized using a twin-screw extruder and 3D Devo Filament maker. 3D printing of samples for mechanical testing was conducted using three (3) raster angles (45o, 60o, and 75o) and various particle sizes of coco coir fiber reinforcement in the PLA matrix. Results showed that the < 74μm particle size of the coco-coir exhibited a 24% and 175% increase in tensile strength and izod impact strength compared to the pure PLA at 60o and 75o raster angles, respectively. Likewise, the reinforcement of <149μm particle size coco coir at 45o raster angle contributes to an increase of 4.8% flexural and 176% compressive strength compared to pure PLA. The study concludes that there is an improvement in the mechanical properties of the PLA-Coco Coir composite at a certain particle size and raster angle in 3D printing.

Mechanical Characterization and Fracture Analysis of Epoxy Resin Composites Reinforced with Quasi-Unidirectional Salago Fibers

The good environmental effect and possible cost reduction which can be achieved by reinforcing natural fibers in composites while improving some properties led to the development of these materials in various fields. In terms of mechanical properties of composites with natural fibers, both fiber loading and their orientation in the matrices are important factors. In this research work, the effects on the mechanical properties of reinforcing quasi-unidirectional salago fiber in epoxy resin were investigated. Varying alkaline treated fiber contents of 5 %, 10 % and 15 % by weight were characterized through tensile, flexural and impact tests. Fracture analysis after mechanical testing was done with the aid of optical microscopy. As the fiber weight content increases, results revealed enhancements on tensile strength, modulus of elasticity, flexural modulus and impact strength. Overall, the 15 wt. % fiber loading obtained the highest mechanical properties with average tensile and Izod impact strengths of 89.2 MPa and 137 J/m, respectively.

Increasing of the steels properties by an ecological method of isothermal and step quenching

The relevance. Improving the mechanical properties of steels makes it possible to increase the service life of machine parts, which is an important task in materials science. One of the promising directions in its solution is to obtain in steel a multiphase structure, one of the main components of which is metastable austenite, which undergoes a dynamic deformation martensitic transformation (DDMT) - self-hardening effect under loading (SHL). Methods providing the required structure are isothermal and step quenching. However, at present, when they are carried out for cooling from the austenitizing temperature and holding at the constant temperature used non-environmentally friendly substances: heated oil, molten salts or alkalis. In this regard the actual problem is the exclusion of them from the technological process. The possibility of solving this problem on several steels has shown.
 Purpose is to show the possibility of increasing the mechanical properties of the studied steels 30ХГСА, 38ХС, 45Г, 40ХН, 10Г12, 60Х18 by using rational modes of an environmentally friendly method of steels quenching (isothermal - for low-alloyed and step - for high-alloyed) due to obtaining in their structure along with other components of metastable residual austenite and the implementation of the SHL effect.
 Research methods. Samples of the investigated steels after austenitization (in some cases with holding in IСIT) were cooled in water to the temperature of lower bainite formation (isothermal quenching) or stabilization of supercooled austenite to martensitic transformation upon cooling (step quenching), after which they were kept in a furnace and cooled in air to room temperature. Durometric, metallographic and X-ray research methods were used. The tensile properties and impact strength were determined. These properties were compared with those obtained for the studied steels after a typical heat treatment, including quenching in oil and tempering.
 Results. It is shown that isothermal and step quenching of the investigated steels without the use of non-environmentally friendly substances, carried out according to rational modes, makes it possible to increase the mechanical properties in comparison with their level after the commonly used quenching in oil (fire hazard, the vapors are cancerogenic) and tempering. This is achieved by obtaining a multiphase structure with metastable austenite.
 Scientific novelty. It is proposed to obtain a multiphase structure with metastable austenite in them to improve the mechanical properties of the studied steels by conducting isothermal and step quenching in an environmentally friendly way without using heated oil, molten salts or alkalis.
 Practical value. For the studied steels the modes of isothermal and step quenching are determined in an environmentally friendly way, which make it possible to increase the mechanical properties in comparison with the level achieved by quenching and tempering. Wherein in contrast to a similar typical quenching method are excluded the costs of purchasing salts or alkalis, their disposal and washing of products from them. Compared to quenching and tempering, the new method does not require the use of oil and tempering. The latter improves ecology and reduces energy consumption during heat treatment.

Influence of Home Composting on Tensile Properties of Commercial Biodegradable Plastic Films.

In recent years biodegradable plastic films have been increasingly used for various purposes, most often as grocery bags and for collecting bio-waste. Typically, the biodegradation of these films should take place in industrial compost facilities where the biodegradation process occurs under controlled conditions. Nevertheless, many of these films are often disposed of in home composting bins, so the aim of this study was to examine the course of biodegradation of compostable plastic films under uncontrolled conditions in garden composting sites during a period of four months. Mechanical properties were tested on seven different commercially available biodegradable films and bags that were placed in a garden composting bin from February to May. Both tensile properties and tensile-impact strength showed some unexpected results in terms of increase of the properties after the first, second, and third month for some films and bags. The same unpredictability was seen in FTIR and TG analyses.

Mechanical Behaviour of Al7075 Hybrid Composites Developed through Squeeze Casting

The automotive and aerospace sector are behind the development of squeeze casting process, as the squeeze cast components exhibit improved mechanical properties. Squeeze casting is a hybrid metal processing technique that combines the advantage of both casting and forging in one operation. The aluminium alloy 7075 is a futuristic material that is widely used to produce automotive and aerospace components. Cylindrical component of AL 7075 was produced by varying the squeeze pressure at certain level. The specimen was made from the component as per ASTM standard and they were tested for mechanical properties such as tensile hardness and impact strength respectively. It was found that mechanical properties were enhanced with increase in squeeze pressure. The aluminium 7075 hybrid composites developed through squeeze casting is fabricated and experimented upon and found to have adequate potential for wide variety of application. In aerospace industries it can be used in gear components, blade sleeves, guide vanes, wing components etc. Applications in surface transport are brake rotors, automotive engine cylinder, engine exhaust valve, body chassis and connecting rods. This material can be used in light weight applications such as power lines and wind mill fans.

Reuse of polyester-glass laminate waste in polymer composites

Purpose: of this paper is to develop a new generation of polymer composite materials that would ensure the use of residual and serious environmental problems of polyester-glass laminate waste. Design/methodology/approach: The glass reinforced polyester waste was ground and added to produce new composites. Thermoplastic - high impact polystyrene was selected for the composite matrix. Composites containing 10, 20, 30% by weight of the filler of polyester-glass laminate powder were made. The process of extrusion and subsequent injection was used to prepare the test samples. The influence of the filler on selected properties of composites was evaluated. The physical properties of the filler as well as the processing properties of the mixture as well as the mechanical properties - impact strength and tensile strength of the obtained composites were investigated. Findings: A decrease in tensile strength and impact strength was observed along with an increase in the amount of filler. Research limitations/implications: It would be interesting to carry out further analyzes, in particular with a higher volume fraction of the filler or with a different composite structure, e.g. using PVC as a matrix. The developed research topic is a good material for the preparation of publications of a practical and scientific nature, especially useful in the research and industrial environment. Practical implications: The shredded glass-polyester waste can be used as a filler of polystyrene, however, the resulting composite could be used to produce parts with slightly less responsible functions such as artificial jewelery or toy elements. Originality/value: Obtained results are a new solution a global waste management solution for glass reinforced polyester waste, which may contribute to the sustainable development of the composite materials industry through the partial utilization of waste composites with a duroplastic matrix.

Mechanical Properties and Thermal Analysis of Salago and Coir Hybrid Fiber Reinforced Epoxy Resin Composites

The utilization of natural fibers in composites continues to increase due to their advantages over the synthetic fiber materials especially in terms of environmental impact and costs. One of the techniques that can be used to further enhance the properties of these natural fiber reinforced composites is through fiber hybridization. In this study, salago and coir fibers were reinforced in the epoxy resin to form a new hybrid composite. The salago to coir fiber weight ratios considered in the fiber hybridization were 3:1, 1:1 and 1:3. The performance of these hybrid fiber composites were compared to pure coir fiber composite and salago fiber composite in terms of impact strength, tensile properties and flexural properties. Among the hybrid fiber composites, the fiber weight ratio of 3:1 has the highest tensile strength (33.8 MPa), tensile modulus (3.57 GPa), flexural strength (44.2 MPa) and impact strength (42.3 J/m). It was found out that the addition of coir to this hybrid fiber composite improves the tensile strength by about 21.1 % as compared to the salago fiber composite. On the other hand, the addition of salago fiber to this hybrid fiber composite resulted to a higher tensile modulus (43.4 %) and impact strength (25.5 %) than the coir fiber composite. Moreover, the thermal analysis of the composites revealed a peak degradation temperature at around 370 °C which is associated to the decomposition of cellulose, hemicellulose and epoxy resin.

Influence of the Alkali Treatment of Flax and Hemp Fibers on the Properties of PHBV Based Biocomposites.

This study assessed the impact of alkali treatment of hemp and flax fibers on mechanical properties (determined by means of the uniaxial tensile test, impact tensile strength test and hardness test), processing properties (the course of the extrusion and injection process) and usable properties (shrinkage of molded pieces, degree of water absorption) of biocomposites on the base of poly (3-hydroxybutyric-co-3-hydroxyvaleric acid) (PHBV) biopolymer. For this purpose, 1 mm of length flax and hemp fibers was surface-modified by means of aqueous solution of NaOH (sodium hydroxide) with concentrations of 2%, 5% and 10%. The composites were made using the extrusion technology. The test specimens were produced by injection molding technology. In total, eight types of biocomposites with modified and non-modified fibers were produced, and each biocomposite contained the same filler content (15 wt.%). Their properties were compared in some cases with pure PHBV polymer. In the case of biocomposites filled with hemp fibers, it was noted that an increase of the alkalizing solution concentration improved most of the tested properties of the obtained biocomposites. On the other hand, in the case of flax fibers, there was a significant decrease in most of the mechanical properties tested for the composite containing fibers etched by 10% NaOH solution. The obtained results were verified by examining fibers and the destroyed specimens with a scanning electron microscope (SEM) and an optical microscope, which confirmed, especially, the significant geometry changes of the flax fibers etched by 10% NaOH solution. This procedure also resulted in a significant change of processing properties—a composite of this fiber type required about 20 °C lower temperature during the extrusion and injection molding process in order to obtain the right product. These results lead to the important conclusion that for each filler of the plant-origin and polymer matrix, the fiber alkalization method should be selected individually in order to improve the specific properties of biocomposites.

Impact Modified Polyvinyl Chloride Based Thermoplastic Elastomers: Effect of Nitrile Butadiene Rubber and Graphene Oxide Loading

A new thermoplastic elastomer with improved impact and tensile properties was produced through melt blending of graphene oxide filled nitrile butadiene rubber (NBR-GO) and polyvinyl chloride (PVC) without the addition of plasticisers and thermal stabilisers. Nitrile butadiene rubber (NBR) compounds, with and without graphene oxide (GO) are prepared through latex compounding method and cured, prior to blending with PVC. The effect of NBR and NBR-GO loading on the process-ability and physico-mechanical properties of PVC blends were evaluated. The addition of NBR and NBR-GO improved tensile strength (TS), impact strength and swelling resistance of PVC. Addition of NBR also increased the stiffness of PVC due to higher elasticity of NBR as compared to PVC. Optimum impact strength, TS and swelling resistance was achieved with the addition of 10 wt. % NBR-GO. Good miscibility between NBR and PVC, and additional reinforcement by GO is responsible for enhancement of impact and TS. NBR-GO showed greater miscibility in PVC as compared to NBR as proven by morphological observation under scanning electron microscope. Morphological observation reveals that micro-cracks formation on PVC/30NBR surface which is responsible for low impact, tensile and swelling properties as compared to PVC/30NBR-GO composite.

Effect of Wood Filler Concentration on Physical and Mechanical Properties of PLA-Based Composites

This paper presents the findings of experimental studies of the physical and mechanical properties of wood-filled composites based on polylactide (PLA) and vegetable filler in the form of wood flour (WF) thermally modified at 200-240 °C. It also reveals the dependence of the tensile strength, impact strength, bending elastic modulus, and density of composites on the amount of wood filler and the temperature of its thermal pre-modification. We established that an increase in the concentration of the introduced filler and the degree of its heat treatment results in a decrease of the tensile strength, impact strength and density of composite materials, while with a lower binder content, thermal modification at 200 °C has a positive effect on bending elastic modulus. We also found that 40 % content of a wood filler heated to 200 °C is sufficient to maintain relatively high physical and mechanical properties of composite materials. With a higher content of a wood filler, the cost can be reduced but the quality of products made of this material may significantly deteriorate. However, depending on the application and the life cycle of this product, it is possible to develop a formulation that includes a high concentration of filler.

Fabrication of bionanocomposites reinforced with hemp nanocellulose and evaluation of their mechanical, thermal and dynamic mechanical properties

The present study aims to fabricate the epoxy-based bionanocomposites reinforced with hemp nanocellulose and the evaluation of their mechanical, thermal and dynamic mechanical properties. Nanocellulose from hemp fibres was isolated via the chemo-mechanical method and its bionanocomposites were prepared using the in situ polymerization method. Although many researchers have reported studies on the preparation and characterization of bionanocomposites however, studies on the mechanical, thermal, and dynamic mechanical properties of epoxy-based bionanocomposites reinforced with hemp nanocellulose are still unreported. The mechanical properties (i.e. tensile, flexural, hardness, and impact) and dynamic mechanical properties (i.e. glass transition temperature, damping behaviour, storage, and loss modulus) of the developed bionanocomposites were investigated. Further, the crystalline behaviour and thermal stability were also studied using the X-ray diffraction and thermogravimetric analysis techniques, respectively. The results revealed that an addition of nanocellulose considerably improved the mechanical, thermal, and viscoelastic properties of the bionanocomposites. As much as 52.17%, 48.17%, 89.08%, and 15.67% improvements in the tensile strength, flexural strength, impact strength, and hardness, respectively, for the 2 wt.% nanocellulose composites were found over the epoxy matrix.

Study of the performance parameters of friction stir welded magnesium AZ31B alloy at optimized process parameters

The present study is aimed to analyze the effect of process parameters on the qualities of the Friction Stir Welded AZ31B Mg Alloy. Response Surface Methodology based Grey Relation Analysis technique was used to multi-optimization of the response parameters such as tensile strength (TS), percentage elongation (El), microhardness (MH), and impact strength (IMP). The mathematical models for response parameters were developed by considering tool rotational speed (RS), tool shoulder diameter (SD), and welding speed (WS) as process parameters. ANOVA (Analysis of Variance) was performed to check the adequacy of the formulated mathematical model and figure out the significant parameters. The results revealed that RS of 950 rpm, WS of 150 mm/min, and SD of 11 mm are the optimal process parameters for optimum response parameters (TS of 157.8700 MPa, IMP of 4.3001 Joule, MH of 84.1335 Hv, and El of 10.0071%). WS is the most significant factor, followed by RS and SD. The grain growth was observed in thermo-mechanically affected zone (TMAZ). The fracture analysis indicated that crack had initiated from the bottom of the centerline in the welded zone and propagated towards the advancing side.

Improving Rheological and Mechanical Properties of Various Virgin and Recycled Polypropylenes by Blending with Long-Chain Branched Polypropylene.

Blends of two long-chain branched polypropylenes (LCB-PP) and five linear polypropylenes (L-PP) were prepared in a single screw extruder at 240 °C. The two LCB-PPs were self-created via reactive extrusion at 180 °C by using dimyristyl peroxydicarbonate (PODIC C126) and dilauroyl peroxide (LP) as peroxides. For blending two virgin and three recycled PPs like coffee caps, yoghurt cups and buckets with different melt flow rate (MFR) values were used. The influence of using blends was assessed by investigating the rheological (dynamic and extensional rheology) and mechanical properties (tensile test and impact tensile test). The dynamic rheology indicated that the molecular weight as well as the molecular weight distribution could be increased or broadened. Also the melt strength behavior could be improved by using the two peroxide modified LCB-PP blends on the basis of PODIC C126 or PEROXAN LP (dilauroyl peroxide). In addition, the mechanical properties were consistently enhanced or at least kept constant compared to the original material. In particular, the impact tensile strength but also the elongation at break could be increased considerably. This study showed that the blending of LCB-PP can increase the investigated properties and represents a promising option, especially when using recycled PP, which demonstrates a real “up-cycling” process.