Papers by Keyword: Ductile

Abstract: Steel has been one of the most widely used materials in land and sea construction due to its advantageous properties, especially carbon steel. This study focuses on molecular dynamics simulation to demonstrate carbon steel’s mechanical behavior. A uniaxial tensile test was conducted for body-centered cubic (bcc) structured carbon steel and pure iron to learn the effect of carbon presence. Both simulation cells were simulated under temperature variation to reveal its effects. It was found that carbon steel is stronger than pure iron based on their value on yield and tensile strength, namely up to 2.434 GPa and 1.368 GPa respectively, which are stronger at room temperature. This study also revealed that carbon steel exhibits better elastic properties with a Young’s modulus of 285.749 GPa, compared to that of pure iron 230.117 GPa. Additionally, this molecular dynamic study also identified another phenomenon, such as brittle-to-ductile temperature of carbon steel at 340 K. Structural explanation is provided in the form of bcc structure fraction during the strain progression and under temperature variation. These findings provide a comprehensive molecular perspective to unveil mechanical properties of carbon steel.

Abstract: Nodular cast iron is a type of cast iron with spheroid graphite surrounded by ferrite matrix and / or pearlite. The size of the graphite and its matrix affects the mechanical properties of the cast iron. This research was conducted to investigate the effect of Magnesium composition on strength, stiffness and toughness of nodular cast iron. Magnesium addition is performed by adding FeSiMg alloys. After that, the composition of magnesium was investigated by using spectrometry. Then tensile test was conducted to obtain the yield strength, tensile strength and modulus of elasticity. Further, impact test was performed to determine the impact energy needed to break the material. The result showed an increase of yield strength, tensile strength and stiffness and a decrease of toughness.

Abstract: Ductile removal behavior of hard and brittle material in the process of machining has always been a sticking topic. A series of nanoscratch tests of K9 glass were conducted with Berkovich probe on nanoindenter XP to investigate the ductile removal process, material deformation and crack damage. It was found that the scratches surface was free from crack damage in the range of the selected scratching parameters and excellent machinability of K9 glass was obtained. The observation also showed that the stable chips were distributed on the sides of the scratches and the deformation of chips was much larger than that obtained in the conventional machining. Meanwhile, a pile-up phenomenon was obvious and the residual depth of scratches was decreased with the increasing of scratch velocity under the same normal load condition.

Abstract: A failure analysis of a broken multi strand wire rope from an offshore platform crane was performed. The wire rope was operated for less than 5 years. The wire consists of seven strands, one central strand and six strands around it. The diameter of the small wires was about 0.78-0.94 mm and the larger wires was a round of 1.52 - 1.78 mm. The large size wires were found fractured by cyclic torsional stresses as characterized by the presence of fatigue cracking originating from the outer surface of the wire. Meanwhile the smaller wires were fractured in a ductile manner under excessive load after the larger wire broken out due to the fatigue mechanism.

Abstract: The article to be presented will cover the whole process done in a fracture test for impact, taking into account the thermal treatment of the sample to be studied. The main objective of this article is to observe, verify, analyze and understand how the temperature difference of several samples influences the type and appearance of the fracture. The impact test have a great importance in industry, is through this that you can verify that the material is ideal for application in the production of equipment and vehicles that operate in high or low temperatures. The evaluation criteria of this trial are the energy absorbed by the sample, and the percentage of its characteristic lateral extension, and the percentage of fracture, ductile or fragile, and corresponding to a ductile fracture mode, in which the test at higher temperatures, the impact energy is relatively large, and fragile fracture mode, being one that as the temperature decreased, the impact energy will suffer decline. The most important result of the impact test is the measure of the energy absorbed by the test body to deform and break, measured by the variance of the gravitational potential energy of the hammer (machine component of the impact test) before and after impact. Therefore, providing the conclusion that the smaller the energy absorbed by the sample, more fragile it is depending on the temperature applied.

Abstract: In this study, an experimental investigation was conducted in order to determine the effect of different adhesive thickness (i.e., 0.1, 0.5, 0.7 and 1 mm) on strength of ductile adhesive joint. The study scope covers both experiment and analysis. In particular, two different types of material, aluminum and stainless steel as adherents were used and joined by using a specific adhesive jig. By using universal tensile machine (UTM), three-point-bending (3PB) test was conducted. To obtain the result from the experiment, continuous load is applied to the adhesive until the adhesive become fracture. The result obtained has enabled the clarification of failure behavior mechanisms and characteristics of adhesive bonding.

Abstract: The wire material of filter mesh is made of 304 grade stainless steel. The failure to run properly was due to the impact of burst and torn. The client also expects that the failure was due to corrosion problems. A visual inspection on the strainer mesh was found covered by brownish rust layers and some scratches at the damaged area. The rusty wire mesh that was washed with pickling acid showed a clean and smooth surface. Energy dispersive spectroscopy (EDS) examination of the rusty wire mesh surface indicated that it was only normal oxide precipitates. Thus, it's proven that there were no signs of severe corrosion attack on the failed sample. SEM micrographs showed the unidirectional scratch effects exist in the damaged area. The fractography study was found there was a typical ductile structure on the fracture surface of the wire. It is proven that the wire mesh was actually still in good condition and has not experienced any embrittlement problems as if it exposed to any corrosive environment. The root cause of the failure is shown by the effect of scratches in which it is usually caused by a mechanical forceful push by a hard object or in other words, it is caused by human error factor.

Abstract: Bolted steel-wood-steel connection is an important fashion of connections in timber structure, the manners of failure loaded parallel-to-grain include bearing, row shear-out, group tear-out and splitting, and the brittle failure modes are predominant in some tested results of bolted connections specimens. End distance, bolt spacing, row spacing and the thickness of wood have important influence on the failure modes, and meanwhile, the bolt diameter can not be neglected. Based on the different failure fashion, the equations of strength were given.

Abstract: This work presents an experimental investigation on micro-milling of fully sintered Zirconia (ZrO₂) with CVD diamond coated end mills. The experiments were conducted on a Kern MMP 2522 micro-milling centre. Diamond coated WC micro end mills with stiff geometry, are employed. Effects of cutting parameters on surface quality were investigated by means of a mixed full factorial experimental design. Surface roughness was measured by a Talysurf 120L profilometer. Surface topography was examined using a scanning electron microscope. The results show that a smaller feed rate was apt to result lower surface roughness. With the increase of cutting length, brittle damages were observed in some tests.

Abstract: Specimens of medium carbon steel were quenched and warm-compressed on a Gleeble 3500 Machine. The microstructure of the specimens was studied by using an optical microscope and a transmission electron microscopy. And the properties were investigated by using tensile tests and hardness tests. Results show that the starting microstructure is lath martensite with a small amount of flake martensite. After 50% compression at 550-650°C, ultrafine grains can be observed in the specimens. The microstructure of the specimens compressed at 600°C is equiaxed ultrafine ferrite grains + nano-carbides and a good combination of strength and ductility is obtained. The tensile strength and total elongation are 861MPa and 19.1%, respectively. The hardness is 233.81Hv.