Mohd Faizul Idham

Mechanical Properties of Aluminium Foam by Conventional Casting Combined with NaCl Space Holder

The purposes of this study were to determine the correlation of the aluminium foams mechanical properties in terms of the effect between its density and porosity as well as between its compressive strength and energy absorption of aluminium foam produced by space holder technique. The space holder used was NaCl particle with three different sizes and conditions. The space holders were completely filled the cavity prior pouring of molten aluminium by CO2 sand casting. Then, the samples underwent machining process to remove surface imperfection after casting, followed by water leaching in ultrasonic cleaner to remove the space holder. The higher the porosity, the lower the compressive strength but then again it acts as good energy absorption. Aluminium foam using NaCl size range of 10-15 mm has the highest energy absorption.

The Effects on Microstructure and Hardness of 0.28% Vanadium and 0.87% Nickel Alloyed Ductile Iron after Boronizing Process

Boronizing/boriding is a thermo mechanical process which produced protective surface layers to enhance the performance of engineering components utilized in mechanical, wear and corrosion. The present study investigate the microstructure and the hardness of boride layers formed on 0.28% Vanadium and 0.87% Nickel alloyed ductile iron after boronizing process. Specimens were boronized at 950° C for 6, 8 and 10 hours holding time before being cooled in the furnace. The microstructure and boride layer formed on the surface of substrates were observed under Olympus BX60 Optical Microscope. Vickers Micro Hardness Tester was also performed to determine the hardness of boride layers. Boride layer was formed by diffusion of the boron into the metal lattice at the surface which composed double phase of FeB and Fe2B with saw-tooth morphology. The results of this study indicated that the thickness of boride layers increased from 109.8μm at 6 hours to 195.4μm at 8 hours holding time before they crack at 10 hours. The hardness of the material surface also increased from 1535 HV to 1623 HV at 6 and 8 hours respectively. In conclusion, the microstructure, borides thickness and hardness of borides layer were depending on boronizing time while temperature kept constant.

XRD Evidence for Phase Structures of Niobium Alloyed Austempered Ductile Iron

This paper presents the changes on phase structures of niobium alloyed ductile iron after austempering process which started by austenitizing process at 900°C and held at 350°C for 1 hour, 2 hours and 3 hours in salt bath furnace. The phase structure were observed by light microscope, and then verified through X-Ray diffraction (XRD). The phase structure of as cast niobium alloyed ductile iron mainly consists of graphite nodules embedded in ferrite and pearlite phases with presence of niobium carbide. Austempering process resulted in the structure of graphite nodules embedded in ferrite platelets and bainitic structures. Increasing the austempering holding times had resulted in coarsening of the ferrite platelets structures and transformation from lower bainite to upper bainite structures.

The Effect of Surface Treatment on 0.16% Chromium and 1.32% Nickel Alloyed Ductile Iron (Di) through Boronizing Process

This paper aim to investigate the effect on microstructure, hardness and wear (slurry erosion) of alloyed ductile iron (DI) with addition of 0.16% Chromium and 1.32% Nickel before and after boronizing process. The specimens were prepared by melting the Ductile Iron compositions through CO2 sand casting method. Specimens were fully coated with boronizing paste and heated at 850°C and 900°C for 8 hours holding time. Microstructures of the specimens were observed under Olympus BX 41M Optical Microscope. Vickers Micro Hardness Tester was used to determine the hardness of the specimens while Wear Test (Slurry Erosion) to measure the wear volume of each specimen. After boronizing process, the boron element diffused into the specimens which make the surface harden. The thickest boride layer was detected at sample with temperature 900°C. The samples of 900°C give higher hardness than temperature 850°C which is 2909 HV and 1395 HV respectively. Referring to surface roughness test, samples boronized at 900oC had high wear resistance compared to sample boronized at 850oC and as cast. The selection temperature in boronizing treatment can prevent the rate of wear thus can identify the hardness of surface in order to prolong the equipment and application or even structure.

Effect of shot blasting on paste boronizing of 316L stainless steel

This investigation was conducted to study on the effect of shot blasting on the case depth of boride layers produced and microhardness after performing paste boronizing on 316L stainless steel. 250 micron diameter of glass beads had been used in the process of shot blasting with variation in the blasting pressure. Paste boronizing was performed at 850°C with 8 hours of soaking time. The samples involved were tested and analyzed on the microstructure and microhardness. Boride layers of FeB and Fe2B formed due to paste boronizing improve the microhardness of 316L stainless steel and the effect of shot blasting with increasing the blasting pressure increase both of case depth of boride layers and microhardness on the studied metal.

Effect of Pack Boronizing on Microstructure and Microhardness of 304 Stainless Steel

The implementation of boronizing in low alloy steel had been implemented tremendously in past years as this method offers excellent surface protection that led to enhancement of hardness and wear of the material. In conjunction to that, few parameters had been recognized as the factor that promotes boron diffusion into the surface of the material which is the selection of boronizing temperature and time. This study concentrated on the effect of pack boronizing on the boride layer thickness of 304 stainless steel which contained high amount of alloying elements. The microstructural analysis and boron layer thickness was measured and observed using optical microscopy and SEM analyzer. The microhardness of the material was measured using Vickers microhardness tester. The results portrayed that boronizing successfully induced boronizing layer containing FeB and Fe2B phases with thickness of 15μm. This resulted in major improvement of the microhardness values with improvement of 5 times compared to non-boronized samples.

Mechanical properties of tempered Ti-Nb alloyed ductile iron

The applications of ductile iron in numerous engineering applications require continuous effort in properties enhancement due to the necessity of product sustainability and performance. The studies highlighted the effect of 0.5 wt% titanium and niobium addition the mechanical properties of tempered ductile iron. The samples were prepared through conventional CO2 sand casting process. Heat treatment was conducted by austenitizing at 900°C for 1 hour and subsequently oil quenching before tempered at three different temperatures which are 500°C, 600°C and 700°C at 1 hour holding time. The mechanical properties were evaluated through impact (ASTM E23) and hardness (Rockwell) test. Microstructure observation and XRD analysis was also performed on as cast and tempered samples. The findings indicated that increasing the tempering temperature at 700°C enhanced the hardness and tensile strength of tempered alloyed ductile iron compared to other samples. The enhancement of the mechanical properties of tempered alloyed ductile iron is expected to further expand the applications of ductile iron.

Effect of two-cycle heat treatment on mechanical properties of ductile iron

The aim of this study is to investigate the mechanical properties of ductile iron after treatment with two-cycle heat treatment processes which modified from austempering. The modified heat treatments have two stages holding temperature. Ductile iron was austenitized at 900 °C for an hour and followed by transferring the sample to other furnace which was set at different temperatures of i) 250 °C; ii) 300 °C; iii) 350 °C without quenching for 1.5 hours. Tensile (ASTM E8M), impact (ASTM-E23-1990) and Rockwell hardness tests were carried out to study the mechanical properties of the ductile iron. It was found that the sample which was heat treated using two-cycle heat treatment process at temperature of 250 °C contributed to better absorbing impact energy properties and hardness properties. Meanwhile, sample that heat treated at 350 °C has higher tensile strength.

Microstructure and XRD of Ductile Iron Using Annealing-Tempering Heat Treatment Process

In this present study, the effect of tempering temperature of annealing-tempering combination processes, on microstructure as well as exploring the phase constituents of ductile iron through XRD analysis were performed. Ductile iron produced through conventional CO2 sand casting method was performed annealing-tempering heat treatment processes by using change furnace method. Three different temperatures were investigated ranging from (i) 250 °C, (ii) 300 °C and (iii) 350 °C for 1.5 hours respectively. Standard metallographic observation and XRD analysis were done to characterize the microstructure and the constituents respectively. It is found that the graphite structure exist in both treated and untreated samples. Pearlitic structure was formed in the microstructure for heat treated samples. Ferritic-pearlitic matrix structure surrounding the graphite nodule has been shown in as-cast sample. Annealing-tempering process does not change the BCC ferrite peak in (200), (211), (220) and (310) planes shown in as-cast.

Corrosion behavior of 0.02–2.0wt% Vanadium alloyed grey iron

This paper focused on corrosion behavior of grey cast iron having 0.02wt %, 0.5wt% and 2wt% vanadium as the alloying elements. Vanadium alloyed grey cast iron samples were produced by using Y - block CO2 sand casting process and poured into double cylinder mould. The corrosion behavior was measured from polarization method, under 3.5% NaCl aqueous solution, conducted at room temperature. The corroded surfaces were then observed through scanning electron microscopy (SEM) and the compositions were obtained through sparked EDX analyzer. The microstructure vanadium alloyed grey cast iron show the presences of graphite flakes surrounded by ferritic structures. The corrosion rate, which was obtained from polarization test indicated that 2% alloyed grey cast iron produced better corrosion resistance compared with 0.02% and 0.5% vanadium alloyed grey cast iron.