Microstructure Photographs Research Articles

PENGARUH ARUS PENGELASAN PADA BAJA ASTM SA 516 Gr70 TERHADAP KEKUATAN TARIK DAN KETANGGUHAN LAS SMAW DENGAN ELEKTRODA E7018

The strength of the weld is influenced by the arc voltage, the magnitude of the current, the speed of welding, the magnitude of the penetration and the electrical polarity. The determination of the magnitude of the current in metal grafting using arc welding affects the efficiency of the work and the weld material. Based on the existing problems, this research aims to determine the effect of low carbon steel welding current on tensile strength, toughness, hardness and micro structure to use SMAW with E7018 electrode using experimental research methodology using low alloy steel ASTM SA 516 gr 70 containing chemical element C = 0.16%, Si = 0.37%, Mn = 0.146%, S = 0.11%, Ni = 1%, Nb = 1%, Cr = 2%, Cu = 0.47%. Material welded with a variation of welding current 110 A, 130 A and 150 A using reverse polarity DC SMAW with E7018 electrode diameter of 3.2 mm. Specimens were tested for tensile strength, toughness, hardness and microstructure photographs with the highest tensile strength results in a variation of 130 A currents with an average of 546.83 MPa which increased by 21.77 MPa from raw materials. The highest yield strength at 130 A current variation with an average of 377.27 MPa which increased by 17.27 MPa from raw materials. The toughness in the highest welding area occurs in the 110 A current variation of an average of 1.85 Joule / mm 2 , it decreases 0.375% of the raw materials. The highest level of hardness occurs in the weld metal area with an average of 201.5 HVN of current variation of 150 A, this show in the micro structure of the grains are softer than the variations of other welding currents.

Badania właściwości powłok na bazie chromu napawanych metodą TIG

The paper presents results of the deposition tests on the steel plates made of X10CrMoNb9-1. The steel sheet has been TIG-deposited using two different materials. Welding process has been performed applying Electric Invertec V270-T pulse device. The materials used for the deposition were W CrMo2Si and W CrMo91. After the process, samples have been cut from the deposited plates, from which the metallographic welds have been made. The paper presents photographs of microstructures recorded during observation of welds under Nikon Eclipse MA 200 inverted microscope.

Airflow patterns in a 3D model of the human acinus

Based on the recent photographs of microstructures of anacinus a novel 3D computational model for airflow and particle transport and deposition was developed. To model the entireacinar region simultaneously, an approach was proposed to reduce the computational space. The airflow was solved using numerical simulations for the cases of expanding and contracting the asinus wall. The volume change of the lung was imposed based on the normal breathing condition with 15% volumetric expansion ratio. Since the entire acinar region was modeled, realistic pressure type boundary conditions were used and the use of earlier unrealistic boundary conditions was avoided. The simulation results showed that the flow patterns in an acinus with moving walls were significantly different from those for the rigid wall case. Furthermore, due to the asymmetric configuration, the flow patterns were not quite symmetric. It was shown that the ratio of alveolar flow to ductal flow rate controlled the dominant flow regime in each generation. Ratios below 0.005led to recirculation regime where flow separation occurred, while values above this threshold led to flows with radial streamlines. In summary, while the flow in the primary generations was characterized by the formation of recirculation regions in the alveoli, the terminal generations were characterized by radial streamlines which move towards the alveolar wall. Both flow regimes had substantial effects on particle deposition in the acinus.

Welding procedures of Turbine Blades by Using ER 309L Austenitic Filler Wire

In the present work it has been investigated the repair of LP-blades steam turbine made of AISI 410 martensitic stainless steels (MSS) by GTAW welding, the repair welding carried out by using ER 309L as consumable filler wire. PWHT was carried out at 1100ᵒC for 1h. The structure-property relationships of the weldments were established based on the current modes employed by utilizing combined techniques of optical microscopy, line/point and EDS analysis. Results showed that Micro-hardness along the base and HAZ regions increased after PWHT as compared to in state of as-welded. After welding process, microstructure photographs of weld-metal region revealed two phase the vermicular δ-Ferrite and γ-austenite matrix. HAZ region consisted of tempered lath martensite with carbides. Line/Point analysis revealed the direction of segregation, whereas chromium was increased in core and depleted in boundary, while nickel was depleted in core and increased in boundary, this support the δ – ferrite was primarily solidified.

The method of quantitative automatic metallographic analysis

A brief analysis of the existing softwares for computer processing of microstructure photographs is presented. The descriptions of the the software package developed by the author are demonstrated. This software product is intended for quantitative metallographic analysis of digital photographs of the microstructure of materials. It allows calculating the volume fraction and the average size of particles of the structure by several hundred secants (depending on the photographs resolution) in one vision field. Besides, a special module is built in the software allowing assessing the degree of deviation of the shape of different particles and impurities from the spherical one. The article presents the main algorithms, used during the creation of the software product, and formulae according to which the software calculates the parameters of the microstructure. It is shown that the reliability of calculations depends on the quality of preparation of the microstructure.

Study of heat deformation influence in surface strain hardening of steel by thermofriction processing

The paper deals with studying the heat deformation influence in the surface strain hardening of steels by thermofriction processing. The main objective of the work was to determine the relationship between the surface heating temperature during TFP, cooling rate, deformation, structure formation and properties of steels, hardened by TFP. The study solved the thermal conductivity problem, which allowed determining the surface heating temperature of samples of steels 15Kh11MF, 65G, U8A, Kh12M in TFP. The photographs of microstructures, which show changes over the cross section of the samples are presented. The presence of surface-hardened “white layer” with increased hardness is obvious, as evidenced by the prints of micro-hardness measurements. The data showed that the deformation mechanism of hardening in a short-term heating of the hardenable surface is predominant in TFP. It is also noted that the “deformed grained martensite” structure is formed, the hardness of which is more than twice the hardness of the martensite structure obtained in hardening of the proposed steels and can be considered as a type of nanostructure.

Effect of tempering on the microstructure and mechanical properties of austenitic dual phase steel

This research is focused on the effect of tempering on the microstructure and mechanical properties of 0.23%C austenitic dual phase steel locally manufactured in Nigeria. The as-received steel was normalized in order to annul the thermo-mechanical history of the steel. Thereafter, some of the normalized samples were austenetized at 850°C for 30 min and then slowly cooled in the furnace to the (α+ϒ) region and soaked for 30 min each at 790, 770, 750 and 730°C; and then quenched in hot water at 50°C. Again, some of the as-step quenched samples were tempered at 320°C for 1 h and air cooled. Mechanical testing and microstructures studies were conducted on all the heat treated samples. Optimum combination of properties was observed with samples intercritically step quenched at 770°C and tempered at 320°C for 1 h. Its hardness, impact strength, total elongation and ultimate tensile strength improved from 241.45 to 327.15 Hv, 0.26 to 1.66 J/mm2, 9.14 to 36.03% and 785.68 to 1569.28 N/mm2 respectively over the as-step quenched steel; representing 35.49, 538.46, 294.20 and 99.74% respectively. Microstructure photographs revealed duplex microstructure essentially comprised of ferrite and martensite with dispersion of carbide or retained austenite which is a typical characteristic of conventional dual phase steels. Key words: Tempering, austenitic dual phase steel, mechanical properties, microstructures.

Influence of Intercritical Annealing Temperature on Mechanical Properties and Microstructure of 0.23%C Low Alloy Steel

The influence of intercritical annealing temperature on the microstructure and mechanical properties of an 0.23%C low alloy steel was undertaken in this work. The as-received steel was normalised and afterwards annealed in the (α+γ) region at 730OC, 750OC, 770OC and 790OC followed by quenching in hot water at about 50OC.Mechanical testing (tensile, impact and hardness) of the annealed samples were conducted at room temperature. The fracture surfaces of the impact test samples were examined using the scanning electron microscope (SEM). Micros structural evolution of the samples was also examined with an optical microscope. The results showed that all the evaluated mechanical properties were improved by intercritical annealing, with the samples treated at 790OC possessing the optimum combination of properties. The ultimate tensile strength (UTS), yield strength (YS), impact strength (IS), total elongation (TEL) and hardness of these samples improved by 2.7%, 13.7%, 19.7% and 31.05% respectively over the normalised sample. The microstructure photographs of the intercritically annealed samples revealed duplex structures of predominantly martensite in a ferrite matrix with little dispersions of either carbide or retained austenite, which is a typical characteristic of conventional dual phase steel.http://dx.doi.org/10.4314/njt.v34i3.11

The Effect of Zirconia Particle Size on Mechanical Properties of Zirconia Toughened Alumina

【The purpose of this study was to investigate the microstructures and mechanical properties of zirconia toughened alumina (ZTA) ceramics prepared from two kinds of 3Y-TZP powders. ZTA composites were prepared by adding two kinds of 3Y-TZP powders, 3YEH (BET = $7m^2/g$ ) and 3YEM (BET = $16m^2/g$ ), to ${\alpha}$ -alumina in the range of 5-25 wt%. It was found that the microstructure photographs of the ZTA composites showed that the average grain size of alumina decreased as the content of zirconia increased. In our present study, specimens containing 3YEM zirconia exhibited smaller grain sizes compared to those of 3YEH zirconia. The Vickers hardness of the ZTA composites that were sintered at $1600^{\circ}C$ for 2 hrs was found to smoothly decrease with increasing zirconia content because of the low Young modulus in zirconia. The Vickers hardness of the ZTA containing 3YEH zirconia was greater than that of the 3YEM zirconia. In substance, the fracture toughness ( $K_{1c}$ ) of the ZTA composites increased as the content of zirconia increased. The fracture toughness ( $K_{1c}$ ) of ZTA containing 3YEM zirconia was greater than that of 3YEH zirconia.】

Change of Aluminum Alloys Structure by Sono-Solidification

Abstract This experiment utilized five Aluminum alloys with silicon content percentages of 7, 10, 12.6, 14.5 and 17(wt)%. Ultrasonic vibration was applied to improve the quality of aluminum alloys. Sono-solidification, in which ultrasound vibrations are applied to molten metal during its solidification, is expected to cause improved mechanical properties due to grain refinement. Observed by microstructure photographs was that grains became smaller and their shapes more regular. Using ultra sound solidification α Al appeared during ultrasound treatment the eutectic solidification time was longest around 10% compared with same condition experiment without ultrasound treatment.

Xylaria in southern China – 8. X. bannaensis sp. nov. and X. brunneovinosa new to the mainland

Two Xylaria species associated with termite nests in China are reported. Xylaria bannaensis is described as a species new to science, and X. brunneovinosa is reported for the first time from Mainland China. The morphological descriptions and photographs of stromata and microstructures are provided based on Chinese materials.

Effect of the particle size of nanosilica on the compressive strength and the optimum replacement content of cement mortar containing nano-SiO2

This research presents the compressive strengths and the microstructure photographs of cement mortars containing nanosilica (NS) with various sizes of 12, 20 and 40nm and then compared with cement mortar with silica fume (SF). Tested results indicated that NS significantly improved compressive strength of cement mortar and the strength improvement was also dependent on the NS particle size. Cement mortar containing NS 40nm gave higher compressive strength compared with NS 12 and 20nm due to their agglomeration and ineffective dispersion. By varying the replacement contents of 3%, 6%, 9% and 12% NS by weight of cement, the optimum replacement content was 9% for all NS particle sizes and SF. These results indicate that the particle size of nanosilica affected only the compressive strength of cement mortar, but it had no effect on the optimum replacement content. The results of microstructure photographs are also supported the compressive strength and optimum replacement content results. NS particles presented high pozzolanic activity and could fill up pores, resulting in homogeneous, dense and compact microstructures.

The thermoluminescence and optically stimulated luminescence properties of Cr-doped alpha alumina transparent ceramics

Abstract Polycrystalline Cr:α-Al 2 O 3 transparent ceramics were fabricated by conventional solid-state processing under vacuum condition. The SEM microstructure photographs of Cr:α-Al 2 O 3 transparent ceramics doped with different content of Cr 2 O 3 were investigated. The absorption, emission spectra, thermoluminescence and optical stimulated luminescence of Cr:α-Al 2 O 3 transparent ceramics were comparable to those of Cr:α-Al 2 O 3 crystals. The influence of different concentration of Cr 2 O 3 on the thermoluminescence and optical stimulated luminescence properties of Cr:α-Al 2 O 3 transparent ceramics was discussed. It showed so interesting results with high TL sensitivity and high stability of OSL signal that Cr:α-Al 2 O 3 transparent ceramics might be a promising material in TL dosimetry and replace Cr:α-Al 2 O 3 crystals.

Hypoxylon from China – 2: H. dengii sp. nov. and H. crocopeplum new to China

Hypoxylon dengii (Xylariales, Xylariaceae) is described from China as a new species, and H. crocopeplum is reported for the first time from the Chinese Mainland. The morphological descriptions and photographs of stromata and microstructures are provided based on the Chinese collections.

The genus Xylaria in the south of China – 3. X. atroglobosa sp. nov.

Xylaria atroglobosa (Xylariales, Xylariaceae) is described from China as a new species. It is characterized by its semi-globose stromata and ascospores with an appendage on one end. Photographs of stromata and microstructures are provided.

EFFECT OF BN/Ti RATIO ON THE REACTION SYNTHESIS OF TiB2-TiNx CERAMICS

The effects of BN / Ti molar ratio on the self-propagating high-temperature synthesis (SHS) reaction behaviors and final products in the Ti - BN system were experimentally investigated. With an increase in the BN / Ti ratio, the combustion temperature and wave velocity first increase and then decrease with the maximum values displaying at BN / Ti =0.67. A substoichiometric TiN 1- x was obtained for BN / Ti <0.67, and a stoichiometric one was produced for BN / Ti =0.67. Moreover, the microstructure photographs of the products reveal that with the increase of the BN / Ti ratio, the grains of the ceramic phases tend to be finer.

Easy method of capturing microscopical images by using a consumer-type digital camera.

Taking pictures of microstructures is difficult, requiring sophisticated cameras coupled by the microscopes. Furthermore, it may not be feasible to find an operating microscope paired with a camera, especially in laboratory conditions. Considering the difficulty of obtaining microscopic photographs in clinical and laboratory settings, this report describes a practical method of digital photography of microstructures using a consumer-type digital camera. The technique can be summarized simply as placing the lens of a consumer-type digital camera over the eyepieces of a surgical microscope, whereby the anatomic structure of interest is focused. The image thus obtained is transferred to the computer, using easily available software programs. The authors conclude that this method is an inexpensive and practical way of capturing photographs of microstructures, obviating the need for using microscopes coupled by the cameras.

The effects of ultrasonic solidification on aluminum

The effect of ultrasound on characteristics of solidified aluminum was shown. An ultrasonic head and ultrasonic system for modification was designed and applied to the crystallizing aluminum melt. The ultrasonic generator allows power of 50-500 W, amplitude of oscillations 10-100 um.m and the operating frequency of 25 kHz. Ultrasonic modification was done by ultrasound introduced from above into the melt. Microstructure photographs show decreasing of the grain size more than five times.

Thermal shock resistance of graphite and carbon/carbon composites in plasma disruption simulation tests

Carbon based materials have been successfully used as plasma facing materials in tokamaks for several years. The behavior of carbon based materials under high heat flux is a decisive issue for the design of first wall structure. Thermal shock tests of carbon based materials have been performed with a Nd:YAG laser and pulsed Nd-glass laser recently. The carbon based materials used in the experiments were graphite and four kinds of three-directional carbon fiber reinforced carbon composites (3D-C/C), which were produced with different manufacturing processes. The duration of laser pulse was 0.1 ms and 1.0 ms, respectively. The laser energy density deposited on specimens was up to 13.3 MJ/cm 2 for single laser pulses. The corresponding value of φ√ t was 42.06 kJ/cm 1 s 1 2 , where φ is the power density of incident laser (kW/cm 2) and t is the duration of the laser pulse (s). The weight loss and crater depth on the specimens and microstructure photographs of radiated specimen surface are given in the paper.

Salt, Phosphate and Oil Temperature Effects on Emulsion Capacity of Fresh or Frozen Meat and Sheep Tail Fat

ABSTRACTThe effects of K2HP04, NaCl and oil temperature on emulsion capacity (EC) and microstructure of fresh and frozen Turkish beef was studied by utilizing a model system. EC of frozen meat was 6.4% higher than fresh meat. EC also increased with increasing phosphate levels increasing 8.5 and 10.4% over the control with 0.50 and 0.75% phosphate respectively. EC increased 1.6% for 3.0% salt over 2.5% salt. Microstructure photographs of the phosphate containing emulsions indicated the protein aggregates diminished and the emulsion was more homogeneous.