Advanced Materials Research Vol. 1119

Abstract: Stellite 6 was deposited by laser cladding on a martensitic stainless steel substrate with energy inputs of 1 kW (MSS-1) and 1.8 kW (MSS-1.8). The chemical compositions and microstructures of these coatings were characterized by atomic absorption spectroscopy, optical microscopy and scanning electron microscopy. The microhardness of the coatings was measured and the wear mechanism of the coatings was assessed using a pin-on-plate (reciprocating) wear testing machine. The results showed less cracking and pore development for Stellite 6 coatings applied to the MSS steel substrate with the lower heat input (MSS-1). Further, the Stellite coating for MSS-1 was significantly harder than that obtained for MSS-1.8. The wear test results indicated that the weight loss for MSS-1 was much lower than for MSS-1.8. It is concluded that the lower hardness of the coating for MSS-1.8, markedly reduced the wear resistance of the Stellite 6 coating.

Abstract: Incremental Sheet Forming (ISF) process is Innovative and cost effective technology trend for forming products in manufacturing industries. The current research is to study and investigate the influence of incremental sheet forming process parameters on response surfaces of aluminium alloy sheet components. In this experiment, Aluminium alloy AA1050 sheet was selected to process forming by using CNC machining centre without expensive dies. Individual and interactive effect of different factors such as, thickness of sheet, tool diameter, vertical step, feed rate, and tool rotational speed at different levels were assessed to improve the processing time. For the design of experiment (DOE), Taguchi’s L27 orthogonal array was used to investigate and optimize the influencing ISF process parameters. From ANOVA results, it was found that for thickness reduction, the influencing factors were as following; feed rate (21.40 %); for roughness, tool rotation speed (20.43 %) and for hardness, thicknesses of sheet (39.49 %). Response Surface Methodology (RSM) showed that optimal values obtained were 0.46 mm, 10 mm, 0.6818 mm, 2232.32 mm/min., and 2626 rpm for thickness of sheet, tool diameter, vertical step, feed rate and tool rotational speed respectively. For percentage thickness reduction of 59.6%, minimum roughness 2.09μm, and maximum hardness 41.7 BHN, the confirmatory test showed values of 64.78 % thickness reduction, roughness of 2.14μm and hardness of 44.82 BHN that were in agreement with the predicted value.

Abstract: Stellite 6 was deposited by laser cladding on a 9Cr-1Mo (P91) substrate with energy inputs of 1 kW (P91-1) and 1.8 kW (P91-1.8). The chemical compositions, microstructures and surface roughnesses of these coatings were characterized by atomic absorption spectroscopy, optical microscopy, scanning electron microscopy and atomic force microscopy. The microhardness of the coatings was measured and the wear mechanism of the coatings was evaluated using a pin-on-plate (reciprocating) wear testing machine. The results showed less cracking and pore development for Stellite 6 coatings applied to the 9Cr-1Mo (P91) steel substrate with the lower heat input (P91-1). Further, the Stellite coating for P91-1 was significantly harder than that obtained for P91-1.8. The wear test results indicated that the weight loss for P91-1 was much lower than for P91-1.8. The surface topography data indicated that the surface roughness for P91-1 was much lower than for P91-1.8. It is concluded that the lower hardness of the coating for P91-1.8, together with the softer underlying substrate structure, markedly reduced the wear resistance of the Stellite 6 coating.

Abstract: In Indonesia, several regions have a minimum quantity or none of fresh water. Self Compacting Concrete (SCC) has a dense microstructure. Knowledge about the microstructure and properties of the individual components of concrete have a relationship that is useful for controlling the behavior of concrete. Porosity and microstructure SCC using sea water as mixing water and curing water discussed in this paper. The results showed the higher the compressive strength of SCC sea water is getting smaller porosity. Porosity on the SCC decreases with increasing quantities of microstructure phase tobermorite (CSH), portlandite (CH), Friedel's salt and ettringite.

Abstract: This investigation presents the lateral quasi-static compression crushing testing and load carrying capacity of three different hexagonal angles ranging from 40^ο to 60^ο. The objective of this study is to understand the effect of hexagonal shape on the progressive deformation, crashworthiness and failure modes. A hand lay-up technique was used to fabricate a hexagonal composite. Quasi-static tests have been carried out on all the specimens tested. From the experimental study, it was found that the tubes crushed with four longitudinal cracks on all sides of the tubes. Furthermore, the energy absorption capability, decreased with the increase of the hexagonal side angles from 40^ο to 60^ο.

Abstract: Drilling through depleted zones and weak formation can prove troublesome since the fracture resistance reduces from its normal boundary [1]. To successfully drill a hole section requires the selection of a low density cement slurry to prevent loss circulation while not exceeding the fracture resistance of the formations exposed. Large number of loss circulation will greatly impact the drilling cost and rig time. This research is focusing on the performance studies of lightweight oilwell cements using foam and cenosphere as the lightweight agents. All tests were conducted according to API Recommended Practice 10B-2. Three performance tests have been conducted such as density test, free water test and compressive strength test. The comparison was made at different percentage of lightweight agents e.g. 10, 20, 30 and 40 percent by weight of cement (%BWOC) respectively. The findings show the performances of formulated foam cement and cenosphere cement are within API limit. However, foam cement can reduce the density of set cement in about 8% greater than the cenosphere cement.

Abstract: This paper investigates the effect of Groundnut Husk Ash (GHA) blended with Rice Husk Ash (RHA) in cement paste and concrete with a view to improve its suitability as a supplementary cementing material. The GHA and RHA used were obtained by controlled burning of groundnut husk and rice husk, respectively in a kiln to a temperature of 600 °C, and after allowing cooling, sieved through sieve 75 μm and characterized. The effects of GHA admixed with 10 % RHA on cement paste and concrete were investigated at replacement levels of 0, 10, 20, 30 and 40 %, respectively by weight of cement. Fresh concrete grade 20 of mixes made with partial replacement with GHA admixed with 10 % RHA in the order as above were tested for workability and hardened concrete tested for compressive, splitting tensile and flexural strengths at curing ages of 3, 7, 28, 60 and 90 days in accordance with standard procedures. The result of the investigations showed that GHA was of low reactivity and RHA was more reactive, with combined SiO_2, Al₂O₃ and Fe₂O₃ content of 26.06 % and 80.33 %, respectively. The use of GHA admixed with 10 % RHA increased consistency, initial and final setting times of cement, but decreased linear shrinkage. The workability, compressive strength, splitting tensile strength and flexural strength of concrete decreased with increase in GHA-RHA content. However, 15 % would be considered as the optimum for structural concrete.

Abstract: Fibre reinforced concrete (FRC) has wide spectrum of advantages in tunnelling. Post-cracking behaviour of FRC wasn’t taken into account by Russian engineers while structural design led to underestimation of material abilities. New approach is based on fib Model Code 2010, which provides residual tensile strength Class of FRC. Research Center “FRC” (http://rcfrc.com/) carried out tests with specimens of different types of FRC, which supported by Russian Foundation for Basic Research. Research involved different specimens – plain concrete and FRC with macro-synthetic fibre of different dosage and types. The results showed the efficiency of each type of fibre. The Class of FRC was defined for each specimen series according to results.

Abstract: The aim of this study is to evaluate the influence of SFRC repairs of different thicknesses on the mechanical performance of RC slabs, especially with respect to the crack pattern and level of cracking load. To understand the influence of SFRC, in terms of performance and variation of cracking load after repairing, a comparison with a reinforced concrete slab without fiber reinforcement was made. The study shows also the mechanical characterization of SFRC through conventional testing, to evaluate compressive strength, fracture energy, tensile strength and toughness. Concerning the application of SFRC on the concrete slab surface, the bond was improved by removing a small amount of superficial material. Finally, the experimental results on cracks distribution, displacements and level of cracking load are shown.

Abstract: Numerical investigations on failure process of rock-like materials with a single flaw were carried out under uniaxial compression based on the fracture analysis software: Fracture Analysis Code in Two Dimensions (FRANC2D/L). The change of the displacements and stress distribution were recorded around the crack. Comparative analysis is made among samples containing different angled flaw, which has great influnce on the process of crack initiation and propagetion, and with the increase of flaw angle from 30° to 75°, peak strength of the specimen increases linearly, basically. Which are in good agreement with those of experiments.