Impact Strength Tests Research Articles

On the role of microstructural properties on mechanical behavior of API-X46 steel

Abstract: The dependence of the mechanical properties respect to the microstructural orientation of a low carbon steel API-5L grade X46 pipe was assessed by Charpy impact and tensile strength tests, through the use of samples oriented in the longitudinal (L) and circumferential (C) directions. Also, a thorough microstructural and EBSD analysis were made. The steel presented anisotropic mechanical behavior, associated with the material forming process. The specimens oriented in the L direction, which is parallel to the microstructural banding, had a lower fracture resistance (KIC-CV) and tensile properties (YS) than the C oriented specimens. According to obtained results, it is concluded that the influence of microstructural banding and crystallographic texture varies the fracture toughness of a material at least 10% between the L and the C directions. Hence, the anisotropy coefficient “rrv” was introduced to correlate quantitatively the microstructural properties to the anisotropic behavior of the API-5L X46 steel. The fracture resistance and tensile strength are mainly influenced by crystallographic texture, while the tensile ductility is associated to the microstructural banding.

Peroxide dynamic crosslinking in impact modification of polypropylene with polybutadiene

Polypropylene was blended with polybutadiene in an internal mixer in order to improve its toughness. The rubber content ranged from 10 to 20 wt. % and dicumyl peroxide (DCP) was added to provide required radicals for dynamic crosslinking of polybutadiene, and for in-situ compatibilization of the phases. This was done using two sequences of mixing. In addition, zinc dimethacrylate was utilized as a co-agent to control chain scission of PP, enhance the interfacial reactions and increase compatibility of the components. In obtaining the optimum blend, the Taguchi orthogonal experimental design was applied and results of Izod impact strength test were concordantly related to crystallinity of the polypropylene, morphology of the blends and reactions that may occur. The impact strength was increased about four times at best in comparison to the neat polypropylene, showing versatility of this way of toughening which may be improved further.

Comparative Evaluation of Impact Strength of Dissimilar Metal Weld between T91 and 304SS Prepared by SMAW and GTAW Techniques

Objectives: The main objective was to evaluate the better joint between dissimilar metals T91 (ferritic) and 304SS (austenitic) prepared by SMAW and GTAW in accordance to their impact strength. Methods/Statistical Analysis: Welding joints between T91 and 304SS were developed using two welding consumables 308L and 309L by SMAW and GTAW respectively. 4 plates of dimension 175mm x 100mm x 6mm were used for welding each of 304SS and T91. Total 9 specimens were prepared according to ASTM A370 standards (55mmX10mmX6mm) for Charpy impact testing, three each from weld bead, HAZ 304SS and HAZ T91 each from SMAW and GTAW welded plates. Findings: Impact strength testing was done with help of Charpy V-notch toughness machine. The standard specimens for Charpy impact testing was placed in the machine and values of impact strength were recorded one after another. As per results, the average impact strength of the weldment prepared by GTAW technique is marginally more as compared to SMAW technique for all sections. The impact strength of the GTAW specimen increases from 304SS HAZ to T91 HAZ passing through the weld metal. The best impact strength is obtained at T91 HAZ of GTAW joint which is 232.67 joules. This increased value of impact strength may be due to movement of carbon particles and formation of carbides and intermetallic. The enhancement in the impact strength is encountered due to increase in micro-hardness which is also published by various authors in the characterization of the weldments. The average impact strength of the weldment prepared by GTAW technique is more as compared to SMAW technique. The dissimilar metal joint prepared by GTAW technique is better joint in accordance to its impact strength. Improvement/Applications: Dissimilar metal joints between austenitic stainless steel and ferritic stainless steel are widely used in various fields like nuclear power plants, steam generators of power plants etc.Keywords: Dissimilar Metal Welding, Gas Tungsten Arc Welding (GTAW), Impact Toughness Comparison, Shielded Metal Arc Welding (SMAW)

Preparation and Test of Conventional Composite Abrasives Using Recycled Alumina Grains

In this work we report the preparation and evaluation of the mechanical characteristics of resin-bond composite abrasives using virgin and recycled alumina grains. The composite abrasives were made with phenolic resin as binder and as-received virgin and recycled alumina grains. Three different recycled alumina grains were studied: i) alumina from wood firing resin-bond abrasive tools; ii) alumina from wood firing vitrified-matrix abrasive tools; and iii) ground alumina from vitrified-matrix abrasive tools. The virgin alumina grains were employed in order to compare the mechanical performance of the prepared composite abrasive. The composition of alumina grains, analyzed by X-ray fluorescence spectroscopy revealed the recycled alumina grains have lower alumina content and higher concentration of silica in vitrified-matrix abrasives samples. The sand blast penetration tests have shown lower penetration depth in the virgin and the ground vitrified-matrix grains composites. The impact strength test results revealed its dependence on the alumina and silica content: samples with higher alumina content present the higher impact resistance whereas samples with higher silica content present lower impact strength.

TO THE ISSUE OF EXTENDING THE SERVICE LIFE OF CARS FOR TRANSPORTATION OF PELLETS

Purpose. Freight rolling stock of «Ukrzaliznytsia» primarily has cars that are overaged. The same situation is observed in the park of specialized cars. So the car fleet for the transport of pellets consists of about 50% of cars that served one-and-a-half and more lifetimes. However, the volume of shipments of iron ore is constant for a number of years. In this regard, there is a need to find methods to justify continuing useful life of cars and to assess the conformity of residual life of the car body structure to operating load for an extended period of use. Methodology. When selecting the cars for the test their condition underwent technical diagnosis in order to identify the level of corrosion and mechanical damage. The next stages of the tests included the experimental determination of the loading level and the stress state of car body carcass based on strength and endurance tests and the evaluation of the possible values of the extended period of operation. Findings. Pre-test diagnosing of cars showed that the technical condition of cars for transportation of pellets, as a whole, is in satisfactory condition. Carried out static and impact strength tests with subsequent evaluation of strength of the car structural elements showed that the strength of the latter is provided in accordance with regulations and such cars do not threaten the traffic safety. Shock endurance tests have shown that all the cars have passed endurance tests with no damage that would impede testing and could not be removed during scheduled repairs. The cars had lifelength that allows prolong their useful life after one-and-a-half lifetime. Originality. The work presents the estimate of the residual life of bodies of pellet transportation cars, which spent one-and-a-half of the set lifetime. Practical value. The experimental results confirm the possibility of extending the service life of cars after one-and-a-half life of their lifetime. The results of the work can be used to extend the service life of cars for transportation of pellets. Part of the rolling stock, which had to be written off in connection with the expiration of the set one-and-a-half lifetime without additional measures can continue its lifetime.

Biocomposite of a multilayer film scrap and curauá fibers

An important material for making composites is the scrap of multilayer films. Using plant fibers in these composites can further contribute to reduce their environmental impact. We prepared, by extrusion and injection molding, composites of this scrap reinforced with 20 wt% of curauá fibers. These were characterized using scanning electron microscopy (SEM); optical microscopy; tensile, flexural, and notched impact strength tests; differential scanning calorimetry; carbonyl index (CI) by Fourier transform infrared spectroscopy; reflectance ultraviolet–visible spectroscopy; and water absorption measurements. The fiber promoted an increase in the flexural and tensile moduli strengths. SEM showed good fiber/matrix adhesion, dispersion of the fibers in the matrix and their fibrillation. Weathering of the surface of the composite during environmental aging was evidenced by CI, degree of crystallinity, melting temperature, and the formation of cracks caused by chemi-crystallization. Despite the environmental degradation of the exposed composite surface, the mechanical properties and interfacial adhesion did not change significantly.

Study on fatigue resistance of low alloy steels with Mo and Cr

This paper presents, based on a case study, the analysis of the factors that influence the mechanical cyclic fatigue resistance of two grades of low alloy steel with Mo and Cr. It was studied the fatigue behavior in real operating conditions of some active elements manufactured from the two low-alloyed steel grades, elements that are equipping some farm implements. Using the fractographic analysis, optical microscopy and scanning electron microscopy, were analyzed the samples that carried away because of the fatigue fracture. On samples taken from the two brands of low alloy steels with Mo and Cr were performed tempering thermal treatments that modified the structure, in order to improve the operating characteristics. The effect of those thermal treatments was initially observed by microstructural analysis of metallographic prepared samples (by polishing and chemical attack using nital reagent), that revealed a troostite type structure. On the heat-treated samples were determined a number of mechanical properties: hardness, impact strength and tensile test. There was observed an improvement of the impact bending strength for both alloys and a tensile behavior that favors increasing resistance to fatigue.

Enhancing the potential of employing thermosetting powder recyclates as filler in LLDPE by structural modifications

Abstract Potential of using powder coating recyclates as filler material for polyethylene compounds was investigated. Due to their strong adhesion to the metal surface during compounding at extrusion temperatures higher than 100°C, the coating powder recyclates were chemically modified to facilitate its processing by extrusion and injection molding at higher temperatures. For this purpose, the coating powder recyclates were first hydrolyzed with addition of an alcohol as swelling agent. The deactivated recyclates were mixed at different ratios with the matrix polymer, a linear low-density polyethylene (LLDPE). The mixtures obtained were then compounded by extrusion and subsequently injection molded to plates to produce specimens for testing. The resulting samples were characterized mechanically by tensile, bending, and impact strength tests. In summary, the powder coatings recyclates can be processed as filler for thermoplastic material, without any adhesion problems up to 160°C and 180°C in the extruder and in the injection molding machine, respectively.

The influence of welding heat input on the microstructure of joints of S1100QL steel in one-pass welding

Microstructure transformations of a welded joint of the of quenched and tempered advanced high-strength S1100QL steel in relation to the heat input and its effect on the strength of the joint. The gas metal arc welding method was used with varying values of the heat input in the range from 5.5 to 7.1kJ/cm. Metallographic examination, hardness, impact strength, and tensile strength tests were carried out. Innovative methodology of welding impact test using drop tower impact resistance tester, has been applied.Joints with strength higher than that of welded steel were created. The amount of heat input necessary to produce joints of S1100QL steel whose strength would be higher than that of parent material was determined. The advantages of using S1100QL steel were indicated and a method of one-pass welding that allows for production of joints of optimum strength parameters with the use of mismatched filler metals was presented.As the result of detailed weld cracking dynamics analysis of the S1100QL steel the course of joint deformation was determined as a function of time, loading force and impact energy. It was found that the dynamically loaded samples welded with lower heat input display higher limit of elasticity, which is manifested by higher loading forces and longer deformation time.

Advanced biocomposite from highly functional methacrylated epoxidized sucrose soyate (MAESS) resin derived from vegetable oil and fiberglass fabric for composite applications

For the two last decades, the depletion of petrochemical resources and the increased global environmental awareness have led to a growing interest in polymers derived from renewable resources. Among the possible technical approaches, using plant-based polymers seems to be the most promising solutions. However, most of the bio-based polymers yield low glass transition temperature (Tg) and low mechanical properties such as modulus and hardness. In this paper, the development of a new generation of highly functional polyester-like polymers for using in composite applications was investigated. These materials were synthesized by mixing methacrylated epoxidized sucrose soyate (MAESS) with styrene as a reactive diluent and using a mixture of Luperox P and Trigonox 239A as a high temperature and room temperature initiators, respectively. E-glass fibers were also used as reinforcements. The prepared bio-based composites were characterized by tensile, flexural, and impact strength testing. Scanning electron microscopy and interlaminar shear strength (ILSS) were examined to study the fiber–matrix interface behavior. To highlight the performance of bio-based MAESS resin in composites, the results of E-glass/MAESS composite were compared against E-glass/VE as a control. The tensile strength and modules of MAESS and VE resins reinforced with E-glass fibers are 532MPa, 36.79GPa and 536MPa, 36.40GPa, respectively. The impact strength of the composites with MAESS resin reinforced with E-glass fibers was 237kJ/m2, whereas that of the vinyl ester resin reinforced with same E-glass fiber was 191kJ/m2. The composites using MAESS were hard and ductile with high modulus and exhibit excellent interface and mechanical properties due to high functionality, rigid and compact chemical structures of MAESS oligomers in the thermoset resin. These bio-based composites have potential uses in variety of composite applications both at low and high temperatures.

THE MAIN GAS PIPELINES MECHANICAL DAMAGE INFLUENCE ON SAFE OPERATION / MAGISTRALINIO DUJOTIEKIO MECHANINIŲ PAŽEIDIMŲ ĮTAKA SAUGIAM EKSPLOATAVIMUI

The influence of mechanical damage of the gas transmission pipelines on safe pipelines operation was researched in the article. The paper presents the main pipelines damage types with actual parameters and influence on operational parameters. The main pipeline Kaunas – Kaliningrad part, which was removed as no longer usable, was analysed. This damaged part was removed and changed to a new part by a responsible company. The hardness measurement and micro hardness measurement, chemical analysis, impact strength test, metallography analysis with an optical microscope were used in experiments. The analysed pipeline part was also regenerated by the computer software ANSYS, which works by the finite elements method. Straipsnyje nagrinėjama magistralinių dujotiekių mechaninių pažeidimų įtaka saugiam jų eksploatavimui. Darbe pateikti pagrindiniai vamzdynų pažeidimo tipai su jiems būdingais bruožais ir įtaka eksploataciniams parametrams. Ištirta magistralinio dujotiekio Kaunas – Kaliningradas dalis, kuri buvo pašalinta, kaip nebetinkama naudojimui. Tyrimams pasitelktas kietumo ir mikrokietumo matavimas, cheminės analizės tyrimas, smūginio tąsumo bandymas. Mikrostruktūros tyrimams naudotas optinis mikroskopas. Tiriamasis objektas buvo atkurtas kompiuterinės programos, veikiančios baigtinių elementų metodu, ANSYS erdvėje.

A COMPARATIVE INVESTIGATION ON PHYSICAL AND MECHANICAL PROPERTIES OF MMC REINFORCED WITH WASTE MATERIALS

Abstract— Aluminium alloy based metal matrix composites (MMC) are produced with agro waste Rice Husk Ash (RHA) and industrial waste Fly Ash as reinforcement. By the continuous stir casting method the MMCs were fabricated in a bottom pouring furnace at 7000C. A rectangular metal mould was used to prepare the casting having dimension 300x50x20 mm3. The effect of adding the different reinforcement were realized through various mechanical behaviour tests. Based upon the standards in the mechanical workshop samples were prepared for measuring mechanical properties such as Impact strength, Compression strength, Tensile strength, Brinell hardness and Density test of both the MMCs. The Fly Ash and Rice Husk distributions in the MMCs were confirmed through the examinations conducted of the microstructure on image analyzer and scanning electron micrographs. Results thus found revealed that there is a great effect of reinforcing Flyash and Rice Husk in aluminium alloy matrix composites. Fly ash gave more enhanced mechanical properties as compared to Rice Husk. Thus selection of waste material from industry based and agro based for reinforcement was found one of the most important criteria for fabricating aluminium matrix composites.

Evaluation of Mechanical and Interfacial Properties of Sisal/Jute/Glass Hybrid Fiber Reinforced Polymer Composites

Natural fiber reinforced composite materials have offered extensive range of properties, such as biodegradability and environmental friendliness. In this experimental study, the partially eco-friendly hybrid sisal/jute/glass hybrid fiber reinforced polymer composites, with varying reinforcements (number of layers) were prepared by using compression moulding process. These composites were characterized by different techniques, for interfacial shear strength, tensile strength, flexural strength, impact strength and water absorption tests. Microscopic examinations were carried out to analyze the interfacial relationship between the fiber and the matrix, fiber dispersion into the matrix and structure of the fractured surfaces, by using the scanning electron microscopy analysis. The results indicated that the hybridization of both sisal and jute fiber with glass fiber, can improve the properties, as compared to single fiber reinforcement of either sisal or jute fiber with glass fiber. Fairly good adhesion and physical properties of these composites indicated their suitability for applications in construction, automobile and aviation industries.

Preparation and Properties of EPDM-Based Composite Coatings with Low Infrared Emissivity

AbstractLow-infrared-emissivity coatings were prepared using metallic particles (including Cu, Al, Ni, Ag, etc.) and an ethylene-propylene-diene monomer (EPDM) binder. The effects of size, shape, morphology, and content of metallic particles on infrared emissivity of the coatings were systematically investigated. The principles of the low-infrared-emissivity and low-solar-reflectance coatings are discussed in terms of reflection, emissions, and chemical structure. The thermal insulation performance of composite coatings is studied via a simulation model. Mechanical properties of composite coatings are studied by using circle-cut test and impact strength test. The composite coatings are also tested for corrosion behavior with potentiodynamic polarization. The results indicate that when the Cu particles and Al particles are flaky and high-leafing, they have the minimum coating emissivity, exhibiting infrared emissivity values of 0.33–0.40 and solar reflectance values of 0.38–0.53. The formation of low-infra...

Application of waste bulk moulded composite (BMC) as a filler for isotactic polypropylene composites

The aim of this study was to produce isotactic polypropylene based composites filled with waste thermosetting bulk moulded composite (BMC). The influence of BMC waste addition (5, 10, 20wt%) on composites structure and properties was investigated. Moreover, additional studies of chemical treatment of the filler were prepared. Modification of BMC waste by calcium stearate (CaSt) powder allows to assess the possibility of the production of composites with better dispersion of the filler and more uniform properties. The mechanical, processing, and thermal properties, as well as structural investigations were examined by means of static tensile test, Dynstat impact strength test, differential scanning calorimetry (DSC), wide angle X-ray scattering (WAXS), melt flow index (MFI) and scanning electron microscopy (SEM). Developed composites with different amounts of non-reactive filler exhibited satisfactory thermal and mechanical properties. Moreover, application of the low cost modifier (CaSt) allows to obtain composites with better dispersion of the filler and improved processability.

Cumulative effect of microwave sterilization on the physical properties of microwave polymerized and conventional heat-polymerized acrylic resin.

Aims:To evaluate and compare the flexural strength and impact strength of conventional and microwave cured denture base resins before and after repeated sterilization using microwave energy to consider microwave curing as an alternative to the conventional method of sterilization.Materials and Methods:The conventional heat cure acrylic resin (DPI heat cure material) Group A and microwave-polymerized acrylic resin (Vipi Wave Acrylic resin) Group B were used to fabricate 100 acrylic resins samples using a standard metal die of (86 mm × 11 mm × 3 mm) dimensions. The criterion was flexural strength and impact strength testing which had Group A and Group B samples; 50 samples for flexural strength and 50 samples for impact strength measurement. For each criterion, five control samples were taken for Group A and Group B. The samples were stored in water before experimenting. The test samples were subject to four cycles of microwave sterilization; followed by flexural strength testing with a 3-point flexural test in universal testing machine (UNITEK 94100) and impact strength testing with impact testing machine (ENKAY Pr09/E1/16).Results:The physical properties had significant changes for conventionally cured denture base resins, whereas no changes found for microwave-cured resins after repeated sterilization cycles.

Effect of Titanium Dioxide Nano Particles Incorporation on Mechanical and Physical Properties on Two Different Types of Acrylic Resin Denture Base

The aim of this study is to clarify the effect of different concentrations of titanium dioxide nanoparticles (Nps) on the properties of two types of heat polymerized acrylic resin. The tested parameters were flexural strength, impact strength, and microhardness. The two types of acrylic resin used in this study were conventional unmodified (Implacryl, Vertex) and high impact heat polymerized acrylic resin (Vertex-Dental, Netherlands). Both types of acrylic resin were modified by using 1% and 5% TiO2 Nps powder. Specimen’s dimensions were prepared according to the American Dental Association Specification No. 12. Three types of specimens were prepared: 1) flexural strength specimens 50 mm × 10 (±0.2) mm × 3 (±0.2) mm, 2) impact strength test specimens 60 mm × 6.0 mm × 4.0 mm, 3) microhardnesss specimens 25 mm × 10 mm × 3 (±0.2) mm. For each test 6 groups were prepared (each group containing 5 samples). Thirty specimens were prepared in each of the three tests, amounting to a total number of 90 specimens. Mechanical properties such as flexural strength (FS), impact strength and microhardness of the above mentioned specimens were determined using universal testing machine, Izod pendulum impact testing machine and Vickers microhardness tester, respectively. ISO Specification No. 1567 was followed in microhardness test. The data was collected and statistically analyzed. Flexural strength considerably decreased by increasing TiO2 concentration in both types of acrylic resin. Impact strength of the conventional acrylic resin modified by 1% of additives significantly increased. The microhardness is significantly increased by addition of 5% of TiO2 Nps. The Incorporation of TiO2 nanoparticles into acrylic resins can adversely affect its flexural strength. Meanwhile, the impact strength can be modified by small percentage of additives (abt. 1%). This effect is directly correlated with the concentration of nanoparticles. On the other hand, concentrations of TiO2 Nps (abt. 5%) positively affect the microhardness of both types of acrylic resin used in the present study.

DEVELOPMENT OF RECOMMENDATIONS FOR EXTENDING THE USEFUL LIFE OF PASSENGER CARS

Purpose. The vast majority of passenger car fleet of «Ukrzaliznytsia» have cars with outlasted service life. In this regard there is a need to find methods to justify the extending useful life of passenger cars and to assess the car body frame residual life conformity to the operating load for the next life time. Methodology. The selection of cars enforced technical diagnostics of cars to detect the level of corrosion and mechanical damage. The following steps provided the car body frame strength analysis on the basis of experimental static and impact strength tests, the longitudinal force effect endurance tests as well as assessment and forecasting of conformity of car body operating life for the next period. Findings The car survey before testing showed that the technical condition of sleeper cars (SSC) is better than that of open-type cars (SOC). So, in SSC cars the thinning of the main load-bearing elements due to corrosion does not exceed 10%, there are no cracks, deformations, rack breakages, etc. At the same time in SOC cars the thinning due to local corrosion reached 35%. There are deformations and corrosion damage of side sill Zshape of both cars, single corner post breakages, damage to the joints of longitudinal tie rod and span bolsters. The conducted static and impact strength tests with following strength assessment of the car structural members showed that the strength of the latter is provided according to the normative documents, and these cars pose no threat to traffic safety. The impact endurance tests showed that all the cars passed the endurance tests without damage, which would prevent from testing and could not be removed during the next depot repair or overhaul, and had life length that allows them to extend the useful life for the next period. Originality. The results of experimental studies show that passenger cars after 28 … 30 and 33… 35 years of operation meet the requirements of strength and safety in accordance with regulatory documents and allow, provided the impact endurance, reasonable extending of the car service life. Practical value. The part of the car fleet, which was to be written off based on the service life, may extend lifespan without additional measures.

Composites of High-Temperature Thermomechanical Pulps and Polylactic Acid

High-temperature thermomechanical pulps (HT-TMP, defibrated at 150 to 170 °C) were compared to a reference TMP (defibrated at 130 °C) as a reinforcement for polylactic acid (PLA). Composites were prepared by melt compounding, followed by injection molding, gradually increasing the used fiber content from 0 to 20 wt.%. The injection-molded specimens were characterized by tensile and impact strength tests, scanning electron microscopy, water absorption tests, and differential scanning calorimetry. The TMP fiber damage was also characterized before and after melt compounding by optical analysis. At 20% fiber content, the Young’s modulus increased significantly, while the tensile strength remained unchanged and the impact strength decreased slightly. All fibers suffered damage during melt compounding, but the tensile strength remained about the same as in pure PLA. All types of TMP were able to increase the PLA rate of crystallization. The HT-TMP fibers were dispersed more evenly in PLA than the 130 °C TMP. The 170 °C TMP produced composites of lower water absorption than the other two TMP types, probably because of its lower hemicellulose content and its higher surface coverage by lignin.

Welding of Prosthetic Alloys / Spawanie Stopów Protetycznych Typu Co-Cr

This paper presents the techniques of joining metal denture elements, used in prosthetic dentistry: the traditional soldering technique with a gas burner and a new technique of welding with a laser beam; the aim of the study was to make a comparative assessment of the quality of the joints in view of the possibility of applying them in prosthetic structures. Fractographic examinations were conducted along with tensile strength and impact strength tests, and the quality of the joints was assessed compared to the solid metal. The experiments have shown that the metal elements used to make dentures, joined by the technique which employs a laser beam, have better strength properties than those achieved with a gas burner.