Effect of second phase particle on fatigue crack growth behavior in microstructure controlled steels

A series of AK-constant fatigue crack growth tests in Paris regime were carried out to investigate the effect of second phase particle on fatigue crack growth behavior of microstructure controlled steels with uniformly distributed hard particles. Three kinds of materials were used in this study, ferrite matrix with pearlite particles (FP), ferrite matrix with bainite particles (FB) and ferrite matrix with martensite particles (FM). The fatigue crack growth tests by using a single edge cracked tension (SECT) type specimen was performed inside a scanning electron microscope chamber equipped with a servo-hydraulic fatigue machine. The results showed that the fatigue crack growth rates for all materials did not coincide with each other, even when the crack growth curves were arranged by the effective stress intensity factor range. From the in-situ observations, crack tip stress shielding phenomena, such as interlocking, branching, etc. were found on the crack wake, which enhanced fatigue crack growth resistance. In ferrite-pearlite (FP) steel, small size and small spacing of hard particles seemed to induce small but frequent crack deflections, which resulted in crack closure phenomena. On the other hand, large size of pearlite particle seemed to induce stress shielding phenomena and then contribute to high crack growth resistance, which was the main reason for higher fatigue crack growth resistance of the large size and spacing of pearlite particle compared to the small size of pearlite particle. It was similar result for the ferrite-bainite (FB) steel where the large size and large spacing of bainite particles enhanced the fatigue crack growth resistance. The higher volume fraction of hard particle also influenced the fatigue crack growth behavior. In this investigation, the result indicated the higher volume fiaction of hard particle in the ferrite-bainite (FBI) steel has significantly increased the fatigue crack growth resistance compared to the ferrite-bainite (FB2) with lower volume fraction and ferrite-pearlite (FP) steels. The effect of hardness of second phase particle was also investigated. The results revealed that the ferrite-martensite (FM) steel showed significantly higher fatigue crack growth resistance compared to the ferrite-pearlite (FP) and ferrite-bainite (FB) steels. From the in-situ observations, the crack tip stress shielding phenomena, such as interlocking, branching, etc were found on the crack wake, which enhanced fatigue crack growth resistance. In the FM steel, the deformation of plastic constrained at the crack tip in ferrite region seemed to induce stress shielding phenomena and then contribute to high crack growth resistance, which was the main reason for lower fatigue crack growth rate of the FM steel with harden martensite particle compared to the FP and FB steels with soften pearlite and bainite particles. Keywords : Fatigue crack growth behavior, AK-constant fatigue crack growth tests, crack tip stress shielding, interlocking, crack closure, ferrite-pearlite, ferrite-bainite, ferrite-martensite, hardparticle, plastic zone size, plastic constrained deformation

Penerapan nilai-nilaimurnidalam kalangan pelajar Sarjana muda pendidikan teknik dan vokasional semasa Menjalankan amali di makmal

Nilai murni ialah nilai yang menjadi asas kepada pembentukan akhlak dan amat penting untuk diserapkan kepada setiap individu khususnya kepada golongan pelajar. Namun demikian menurut kajian-kajian lepas, nilai murni masih kurang diterapkan dengan memuaskan dalam kalangan pelajar terutamanya semasa menjalankan keija amali di makmal. Oleh yang demikian kajian ini dijalankan bagi mengenal pasti sejauh mana pelajar dan pensyarah menerapkan nilai-nilai murni semasa proses pengajaran dan pembelajaran di makmal. Seramai 226 orang pelajar Saijana Muda Pendidikan Teknik dan Vokasional (PTV) menjadi responden dalam kajian ini. Soal selidik merupakan instrumen utama dalam kajian ini di samping temu bual dan pemerhatian sebagai instrumen sokongan. Data-data dikumpulkan dan dianalisis menggunakan perisian SPSS Versi 12.0 bagi mendapatkan min, sisihan piawai dan inferensi ANOVA manakala analisis kandungan bagi data temu bual dan pemerhatian. Dapatan kajian menunjukkan pelajar menerapkan kesemua nilai murni yang terlibat dalam kajian ini. Walau bagaimanapun didapati hanya sebahagian sahaja pensyarah menerapkan nilai-nilai murni kepada pelajar semasa proses pengajaran dan pembelajaran di makmal. Oleh yang demikian, pengkaji mengemukakan beberapa cadangan untuk memastikan pensyarah dan pelajar menerapkan nilai-nilai murni antaranya ialah pihak Universiti Tun Hussein Onn Malaysia (UTHM) perlu membuat penyeliaan dari masa ke semasa bagi memastikan pensyarah dan pelajar bersama-sama menerapkan nilai-nilai murni semasa proses pengajaran dan pembelajaran di makmal

Effect of hardness of second phase particle on fatigue crack growth behavior of steels with hard second phase particle in soft ferrite matrix

ΔK-constant fatigue crack growth (FCG) tests were conducted on low carbon steels with uniformly distributed hard particle with different of pearlite, bainite and martensite in a soft ferrite matrix. The FCG tests by using a single edge cracked tension (SECT) type was performed inside a scanning electron microscope chamber equipped with a servo-hydraulic fatigue machine. During the test, in-situ crack path observation was carried out to identify the crack tip stress shielding phenomena. From the results, influence of hardness of second phase particle on the FCG behavior in Paris regime was systematically investigated. The results revealed that the ferrite-martensite (FM) steel showed significantly higher FCG resistance compared to that of ferrite-pearlite (FP) and ferrite-bainite (FB) steels. The harder second phase particle would be more difficult to be plastically deformed, which would induce higher plastic constrain. This higher plastic constrain may result in significant crack closure effect and stress shielding effect, thereby increasing higher FCG resistance

The primary study of peat soil in wood plastic composite

The major factor driving the growth of the global wood plastic composite (WPC) market is the increasing use of wood plastic composites by the construction and construction sectors for various applications. However, the current WPC is worth examining as this composite can be analyzed by increasing its strength. Therefore, this study was conducted to study the effect of peat soil (PS) on the mechanical properties of wood plastic composite systems reinforced with kenaf fibers. This study uses 4 different composite proportions of i) 10% kenaf fiber and 90% polypropylene ii) 20% kenaf fiber and 80% polypropylene iii) 30% kenaf fiber and 70% polypropylene and iv) 40% kenaf and 60% polypropylene fiber with peat soil added 3%, 6% and 9%. The particle size for peat is 60μm. The method used to produce this wooden plastic composite is by mixing method and injection molding.The test performed on the sample is tensile test and flexural test. The results of tensile test are determined and show that 6% PS is reinforced with 10% KF and 90% PP has the highest tensile strength of 25.23 MPa. While the best results of flexural test were obtained with 3% PS reinforced with 10% KF and 90% PP had a maximum bending strength of 32.40 MPa

Effects of size and spacing of uniformly distributed pearlite particles on fatigue crack growth behavior of ferrite–pearlite steels

Fatigue crack growth tests of three ferrite–pearlite steels with different size and spacing of pearlite particles, which were uniformly distributed in the ferrite matrix, were carried out to investigate the effect of microstructure on fatigue crack growth behavior in the Paris regime. The fatigue crack growth rates for the three materials did not coincide with each other, even when the crack growth curves were arranged by the effective stress intensity factor range. From in situ observations, crack tip stress shielding phenomena, such as interlocking and branching, were found on the crack wake, which enhanced fatigue crack growth resistance. A small size and spacing of pearlite particle seemed to induce small but frequent crack deflections, which resulted in crack closure phenomena. On the other hand, the large size of the pearlite particle seemed to induce stress shielding phenomena and, thus, contribute to high crack growth resistance, which was the main reason for the higher fatigue crack growth resistance of the large size and spacing of pearlite particles compared to the small size of pearlite particles

Simulation and experimental study of double holes film cooling

In the modern gas turbine, film cooling has been widely used to provide thermal protection for the external surface of the gas turbine blades. Numerous number of geometrical arrangement film cooling have been presented for the past 50 years. The main inspiration of the presented geometrical arrangements film cooling are to minimize the effect of lift off phenomena caused by the formation of the Counter Rotating Vortex Pair (CRVP) which commonly discovered in the Single Cylindrical Hole (SCH) arrangement. In order to reduce the CRVP effects, tremendous efforts from the past researchers have been made including the introduction of the Double Cylindrical Hole (DCH). The present study has made use this DCH along with the employment of several geometrical arrangements including pitch distance (POD), length between holes in streamwise direction (LoD), compound angle and upstream ramp. The evaluation of these parameters involved three different blowing ratios, M and two value of the turbulence intensities, Tu. The diameter of the cooling holes in the present study is 4.75mm which taken based on the previous study. The present study has been divided into two major studies namely experimental study and simulation study. The purpose of the experimental study is to validate the present simulation study which making use of an open end wind tunnel. As the validation process shows a good agreement results, 14 more models have been built and tested using simulation study which the total cases considered are 105. As for the result, all the considered cases of DCH shows improvement in comparison with SCH. Each of the considered geometries and flow parameters have their own effects on the film cooling effectiveness which will be elaborate in details in the further chapter. As conclusion, the simulation is having good agreement with the present experimental study and the previous study which is essential to confirm the reliability of the study. Meanwhile, all DCH shows improvement in term of film cooling effectiveness on each of blowing ratio value

Preparation of Innovative PEG/Tannic Acid/TiO2 Hydrogels and Effect of Tannic Acid Concentration on Their Hydrophilicity

Hydrogels are materials that can be used in biomedical and medical applications and have gained increasing interest in recent years. In order to obtain a wide variety of properties, hydrogels containing more innovative components still need to be produced and investigated. In this study, for this purpose, an innovative injectable polyethylene glycol (PEG)/tannic acid (TA)/TiO2 hydrogels were prepared and their properties were investigated. TA, used as a crosslinker for PEG, was used in different concentrations (400 mg, 800 mg, and 1.2 g) in hydrogel preparation to analyse the effect of tannic acid on the properties of the obtained hydrogels. PEG/0.4TA/TiO2, PEG/0.8TA/TiO2 and PEG/1.2TA/TiO2 hydrogels prepared by using FeCl3 to increase the crosslink density in its content and by adding TiO2 due to its antimicrobial properties, were characterized by UV-VIS spectroscopy, FTIR and contact angle measurements. . With the UV-VIS and FTIR spectra, it is seen that TA/Fe3+ metal complexes are formed and the three-dimensional hydrogel network is successfully completed with the help of these metal complexes formed by the addition of FeCl3. In addition, the contact angle measurements of the PEG/0.4TA/TiO2, PEG/0.8TA/TiO2 and PEG/1.2TA/TiO2 hydrogels were found to be 18°, 27° and 27° degrees, respectively, and the hydrophilicity of the hydrogels was reached at constant value in the samples added 0.8 g TA. The obtained new injectable PEG/TA/TiO2 hydrogel is promising for use in biomedical and medical fields, thanks to its contact angle values ​​of less than 90° for biocompatibility and its biocompatible components

Mechanical Behavior and Microstructural Analysis of Molybdenum-TZM Alloy Subjected to Different Annealing Temperature

Mo-TZM alloy is one of the most famous economic molybdenum-based alloys. The percentage of chemical composition in mass of Mo-TZM alloy are Mo-0.5Ti-0.08Zr-0.03C. By adding some Titanium and Zirconium so that the mechanical properties and recrystallization temperature of molybdenum has been corresponding improvement. The purpose of this study is to determine the effect of different annealing temperature on mechanical properties of Mo-TZM alloy. The samples will be heated at two different temperature which are 1000 oC and 1300 oC in 1 hour and 40 minutes to change their microstructure behavior. The mechanical properties of the sample like hardness will be analyzed by using Vickers Micro hardness test. The force applied is 4.903 N and Vickers micro hardness number is 0.5 HVN for 10 second. Then to observe the microstructure changes, optical microscope and Scanning Electron Microscope (SEM) is be used. At annealing temperature 1000 oC, it show values of hardness is 249.54 VHN and the grain boundary size is 0.0898mm. While at annealing temperature 1300 oC, it show the lowest values of hardness which is 243.55 VHN and the highest grain boundary size which is 0.1068 mm. By doing annealing heat treatment it will decreases hardness values and increases the size of grain boundar

The Ability of Crystalline and Amorphous Silica from Rice Husk Ash to Perform Quality Hardness for Ceramic Water Filtration Membrane

  Silica is an inexhaustible resource on earth. It can be found in food-based natural resources. The natural tendency of silica mainly is to contribute to the strength and the hardness of the ceramic material. This paper investigates the hardness formed in ceramic filtration membrane made by amorphous and crystalline silica from rice husk. Four samples from this material were studied based on unwashed and washed material with chemical, namely, crystalline silica treated with chemical (CS1), crystalline silica untreated with chemical (CS2), amorphous silica treated with chemical (AS1) and amorphous silica untreated with chemical (AS2). To acquire the silica phases, the rice husk was experienced to combustion process at 700ºC and 1000ºC for 2 hours. The properties of the silica were obtained by using Scanning electron microscopy (SEM) and x-ray diffractometer (XRD) while the value of the hardness was tested by using microhardness tester machine. As a result from SEM both samples of AS1 and AS2 produced an irregular, crinkled, or grainy surface of silica and for sample CS1 and CS2 produced were flushed, unwrinkled and planar surface. For the high hardness value, crystalline silica treated with chemical (CS1) sample was obtained with 171.0

The effect of heat treatment on compression strength of recycled AA6061 aluminium chips

Solid state recycling aluminium AA6061 chips by cold compaction is a technique that used lower energy consumption and operating cost compared to the conventional recycling technique by casting. This research is to investigate physical characteristics of the milled recycling aluminium AA6061 according to the change of the time (heat treatment) using the high speed milling process and followed by a cold press forging process. Physical property of the recycled aluminium chip of AA6061 were studied. On the other hand, the results were showing that the porosity and density, and compression is correlated. At 8 hours on variable of quenching have a best value porosity (1.95%), density (2.55 g/cm3 ) and compression strength (315.19 MPa). While for the variable of aging, the best value of density (2.54 g/cm3 ) and compression strength (280.76 MPa) is at 10 hours. On porosity the best value is at 8 hours (2.79 %). It must be considered to the density and compression strength. For that, 10 hours were chosen for the best aging time. It can be concluded; the best quenching time is 8 hours and aging time is 10 hours