scholarly journals Melt Treatment-Porosity Formation Relationship in Al-Si Cast Alloys

2021 ◽  
Author(s):  
Dominique Gagnon ◽  
Agnes M. Samuel ◽  
Fawzy H. Samuel ◽  
Mohamed H. Abdelaziz ◽  
Herbert W. Doty
Keyword(s):  
Electron Probe ◽  
Solidification Rate ◽  
Optical Microscope ◽  
Image Analyzer ◽  
Grain Refining ◽  
Porosity Formation ◽  
Optical Microscope Image ◽  
Melt Treatment ◽  
Cast Alloys ◽  
Hydrogen Level

The present study focuses on the porosity formation in three Al-Si cast alloys widely used in automotive industries viz. A319.0, A356.0, and A413.0 alloys under various conditions: stirring, degassing. Sr level, amount of grain refining, combined modification and grain refining, as well as hydrogen level. The solidification rate was the same for all alloys in terms of the mold used and its temperature. The microstructural investigations were carried out quantitatively using an optical microscope-image analyzer system scanning systematically over a polished sample area of 25 mm × 25 mm and qualitatively using an electron probe microanalzer equipped with EDS and WDS systems. The results were coupled with hardness measurements.

Application of Inclined Cooling Plate to Fabrication of Semi-Solid Cast Iron

2007 ◽  
Vol 544-545 ◽  
pp. 195-198 ◽  
Author(s):  
Sung Yong Shim ◽  
Hwan Goo Seong ◽  
Jin Ho Jeong ◽  
Su Gun Lim
Keyword(s):  
Cast Iron ◽  
Solidification Rate ◽  
Optical Microscope ◽  
Peak Hardness ◽  
Image Analyzer ◽  
Cast Irons ◽  
Cooling Plate ◽  
Relative Extent ◽  
Iron Specimen ◽  
Semi Solid

The influence of angles of inclined cooling plate on cast structure and mechanical properties of cast iron was investigated experimentally in 3.1 wt.% C containing hypoeutectic semisolid cast irons fabricated by flowing the molten melt over the inclined cooling plate and pouring into a preheated permanent mold. The variables used in this study were angles of the cooling plate (5 ~ 15 deg) and the mold temperatures (500~700 deg). The microstructure of resultant specimens were characterized by measuring grain sizes of primary austenite and its solid fraction, using an optical microscope equipped with a digital image analyzer. It was shown that the spherical-like austenite (1.4 aspect ratio) was formed at the cast iron specimens prepared in employing a 10 deg angle of the inclined cooling plate. This was ascribed to the relative extent of duration time of the flowing melt which determine the solidification rate of the melt. The peak hardness and impact values were achieved in the semi-solid cast iron specimen with relatively more spherical austenite. The measured values were approximately 44HRC and 1.71 J/cm2.

Effect of Cooling and Isothermal Aging on Microstructure Using Electroless Nickel (Boron) Plating

2014 ◽  
Vol 695 ◽  
pp. 352-356
Author(s):  
Hardinna Wirda Kahar ◽  
A.M. Zetty Akhtar ◽  
Siti Rabiatull Aisha Idris ◽  
Mahadzir Ishak
Keyword(s):  
Cooling Rate ◽  
Electroless Nickel ◽  
Optical Microscope ◽  
Air Cooling ◽  
Image Analyzer ◽  
Cooling Rates ◽  
Optical Microscope Image ◽  
Finish Material ◽  
The One ◽  
Relationship Of

This paper presents a study on relationship of cooling rates towards the intermetallic compound (IMC) morphology. Cooling rate is an important parameter as it has significant effect towards the IMC microstructure formation that indirectly affects solders joint reliability. However, there is still insufficient study regarding the effect of cooling rate on the IMC thickness and microstructure behavior by using Nickel Boron as surface finish material in the electronic packaging industry. In this study, Sn-3Ag-0.5Cu solder was used on Nickel Boron as coating layer. Cooling rates were obtained by cooling specimens in different media which is water and air. The elemental composition was confirmed using Energy-dispersive X-ray spectroscopy and the microstructure of each IMC then analyzed using optical microscope, image analyzer and ImageJ. In this study, faster cooling rate (water) found to provide thicker IMC (6μm) compared to the other medium used. The morphology shape of each IMC also differs between different medium of cooling. IMC that undergoes faster cooling showed continues like layer while the one using air cooling formed scallop like IMC.

Wettability of CNT-Doped Solder under Isothermal Aging

2016 ◽  
Vol 857 ◽  
pp. 76-78
Author(s):  
Norliza Ismail ◽  
Roslina Ismail ◽  
Nur Izni Abd Aziz ◽  
Azman Jalar
Keyword(s):  
Carbon Nanotubes ◽  
Contact Angle ◽  
Isothermal Aging ◽  
Optical Microscope ◽  
Image Analyzer ◽  
Solder Paste ◽  
Reflow Process ◽  
Weight Percentage ◽  
Test Board ◽  
Free Solder

Wettability for lead free solder 99.0Sn-0.3Ag-0.7Cu (SAC237) with addition of different weight percentage carbon nanotube after thermal treatment was investigated. SAC 237 solder powder with flux was mixed with 0.01%, 0.02%, 0.03% and 0.04% carbon nanotubes (CNTs) to form SAC-CNTs solder paste. Printed solder paste on test board with Cu surface finish was then reflow under 270°C temperature and isothermal aging at 150°C for 0,200 and 400 hours. Wettability of SAC-CNT solder was determined by measuring contact angle using optical microscope and image analyzer. As a result, from reflow process right through 400 hours of thermal aging, SAC237 with 0.04% CNT has the lowest contact angle as compared to other SAC-CNTs and SAC237 solder. As a conclusion, addition of carbon nanotubes into solder SAC237 improved their wettability on Cu substrate, especially at 0.04% of CNTs.

scholarly journals Evolution of Microstructure and Microsegregation of Ti-45Al-8Nb Alloy during Directional Solidification

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Xiangjun Xu ◽  
Rui Hu ◽  
Junpin Lin ◽  
Jian Guo
Keyword(s):  
Mushy Zone ◽  
Solidification Rate ◽  
Solidus Temperature ◽  
Melting Zone ◽  
Optical Microscope ◽  
Directionally Solidified ◽  
Good Oxidation Resistance ◽  
Columnar Grains ◽  
Columnar Grain ◽  
Evolution Of Microstructure

High Nb-containing TiAl alloys have good oxidation resistance and mechanical properties, but the microstructure and the properties are substantially affected by the segregation. To quantitatively investigate the segregation behavior of Al during solidification, microstructures of directionally solidified (DS) Ti-45Al-8Nb (in atomic percent) alloy prepared at withdrawing rates of 30 μm/s and 200 μm/s and a temperature gradient of 4200 K/m were observed by optical microscope and electronic probe microanalyzer. The microsegregations were characterized by wave dispersive spectroscopy. The results show that the DS ingots include the no melting zone, directionally solidified zone with columnar grains, mushy zone, and quenched liquid zone. The primary dendritic arm spacings are 353 μm and 144 μm, respectively, for the two ingots. But the solidified microstructures of the ingots are large lamellar colonies, which contain a few B2 patches and γ bands induced by microsegregation. From dendritic zone to columnar zone, the volume fractions of B2 patches and γ bands decrease. The segregation extents of Al and Nb decrease with the increase of solidification rate. There exists an obvious back diffusion process of Al during solidification and cooling after solidification. According to evolution of Al concentration profiles from mushy zone to columnar grain zone, interdiffusion coefficient for Al in β-Ti at near solidus temperature is semiquantitatively calculated, and the value is (6 – 11) × 10−11 m2/s.

The Mineral Characteristics and Occurrence of Gold in Nali Gold Deposit, Guangxi

2014 ◽  
Vol 936 ◽  
pp. 2383-2388
Author(s):  
Zhi Wen Li ◽  
Cheng Dong Liu ◽  
Xuan Qing Zhao ◽  
Jian Hui Lu ◽  
Guo Lin Guo
Keyword(s):  
Gold Deposit ◽  
Mineral Composition ◽  
Electron Probe ◽  
Mining Area ◽  
Optical Microscope ◽  
Analysis Techniques ◽  
Mineral Characteristics ◽  
Ore Minerals

Using the analysis techniques of polarizing optical microscope and electron probe, mineral composition, ore texture and structure and the occurrence of Au in the primary ore are studied. The research shows that the main ore minerals in the ore include realgar, pyrite and arsenopyrite etc. Sulfur-stibarsen is the main carrier of Au, and is the major associated mineral of realgar, surrounded mainly by realgar, and partly is the associated mineral of arsenopyrite. The existence of visible gold and microscopic gold in the ore of this mining area can be excluded, and the gold might exist mainly in the form of inclusion gold, which is the so-called “nanoAu”.

Porosity Formation and Prevention in Pulsed Laser Welding

2006 ◽  
Vol 129 (8) ◽  
pp. 1014-1024 ◽  
Author(s):  
Jun Zhou ◽  
Hai-Lung Tsai
Keyword(s):  
Laser Welding ◽  
Molten Metal ◽  
Solidification Rate ◽  
Pulsed Laser ◽  
Deep Penetration ◽  
Pulse Profile ◽  
Porosity Formation ◽  
Pulsed Laser Welding ◽  
Laser Welds ◽  
Solidification Processes

Porosity has been frequently observed in solidified, deep penetration pulsed laser welds. Porosity is detrimental to weld quality. Our previous study shows that porosity formation in laser welding is associated with the weld pool dynamics, keyhole collapse, and solidification processes. The objective of this paper is to use mathematical models to systematically investigate the transport phenomena leading to the formation of porosity and to find possible solutions to reduce or eliminate porosity formation in laser welding. The results indicate that the formation of porosity in pulsed laser welding is caused by two competing factors: one is the solidification rate of the molten metal and the other is the backfilling speed of the molten metal during the keyhole collapse process. Porosity will be formed in the final weld if the solidification rate of the molten metal exceeds the backfilling speed of liquid metal during the keyhole collapse and solidification processes. Porosity formation was found to be strongly related with the depth-to-width aspect ratio of the keyhole. The larger the ratio, the easier porosity will be formed, and the larger the size of the voids. Based on these studies, controlling the laser pulse profile is proposed to prevent/eliminate porosity formation in laser welding. Its effectiveness and limitations are demonstrated in the current studies. The model predictions are qualitatively consistent with reported experimental results.

Effect of Warm Deforming and Heat Treating on Microstructure and Mechanical Properties of Mg-Zn-Zr Magnesium Alloy

2012 ◽  
Vol 472-475 ◽  
pp. 707-711
Author(s):  
Guan Lu ◽  
Ya Qin Yang ◽  
Bao Cheng Li ◽  
Zhi Min Zhang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Cast Alloy ◽  
Hot Extrusion ◽  
Heat Treating ◽  
Optical Microscope ◽  
Tensile Fracture ◽  
Strengthening Effect ◽  
Zk60 Alloy ◽  
Cast Alloys

In this paper, the effects of hot extrusion and T5、T6 heat treatment on the microstructures and mechanical properties of ZK60 magnesium alloys are investigated by optical microscope, electronic scanning microscope and mechanical testers. The result shows that both the tensile strength and the elongation of the ZK60 alloy extruded at 380°Care much higher than that of the as-cast alloys, as there are much granular second phases precipitated during the extrusion. The tensile strength of the extruded and T5 treated alloy increases while the elongation decreases faster than that of the extruded alloy. The strengthening effect of the T6 treatment is inferior to that of the T5 treatment. The tensile fracture of the as-cast alloy is brittle fractured while that of the extruded and T5 treated alloy is ductile fractured with lots of deep and even dimples.

Effect of Mould Runner and Coating on Graphite Nodule Characteristics and Hardness of Thin Wall Ductile Iron

2011 ◽  
Vol 264-265 ◽  
pp. 266-271 ◽  
Author(s):  
Hassan Jafari ◽  
Mohd Hasbullah Idris ◽  
Ali Ourdjini ◽  
Hamid Reza Bakhsheshi Rad ◽  
Seyed Sadegh Khayat Ardestani ◽  
...  
Keyword(s):  
Molten Metal ◽  
Ductile Iron ◽  
Hardness Test ◽  
Optical Microscope ◽  
Graphite Nodule ◽  
Carbon Equivalent ◽  
Image Analyzer ◽  
Thin Wall ◽  
Save Energy ◽  
Hardness Values

Due to its attractive characteristics, thin wall ductile iron (TWDI), has been increasingly considered as a preference for reducing material consumption in order to save energy and contribute less environment pollutions as well as decreasing costs. In this research, the effect of two mould runner gating systems and mould coating on graphite nodule characteristics and hardness values of TWDI casting was studied. Strip samples with various thicknesses of 2.3, 3.3, 4.5, 5.4, 6.5, 7.5 and 8.5 mm were casted into CO2 Silicate moulds designed by two gating systems namely stepped and tapered runners. Half of the moulds were coated by graphite-based zircon material to investigate the effect of mould coating on the graphite nodule qualities and quantities. The molten metal prepared contained carbon equivalent (CE) of 4.29% and was poured at the temperatures of 1450°C. Optical microscope (OM) and Clemex Image Analyzer (CIA) were used to evaluate graphite nodule count, roundness and diameter of the nodules of the TWDI cast samples. Brinell hardness test was performed on all samples. The results show that roundness and graphite nodule counts in the microstructure of the samples produced in stepped runner gating system and uncoated mould decrease whereas graphite nodules diameter shows opposite behaviour. Furthermore, molten metal experienced a superior fluidity in coated moulds. Moreover, the TWDI samples achieved a significant improvement in the value of hardness.

Influence of heat input and solubilizing heat treatment on the impact properties of SAW joints in SAF 2205 duplex steel

2012 ◽  
Vol 1381 ◽  
Author(s):  
M. Merlin ◽  
R. Vazquez-Aguilar ◽  
C. Soffritti ◽  
A. Reyes-Valdes
Keyword(s):  
Heat Treatment ◽  
Heat Input ◽  
Welding Process ◽  
Optical Microscope ◽  
Image Analyzer ◽  
Secondary Phases ◽  
Impact Properties ◽  
Steel Joints ◽  
Saf 2205 ◽  
The Impact

ABSTRACTIn this study the influence of heat input (HI) and heat treatment on submerged arc welded duplex SAF 2205 steel joints has been evaluated. In particular, multi-pass welding operations have been performed on 18 mm thick plates using four different heat inputs; a post-weld solubilizing heat treatment has been carried out in order to reduce the microstructural effects on the structure of the heat affected zone (HAZ). Instrumented impact strength tests have been performed on Charpy samples machined from the welded joints; the total absorbed energy and the two complementary contributions of initiation and propagation energies have been evaluated and correlated to the percentages of ferrite and austenite. The microstructures and the fracture profiles have been observed using an optical microscope (OM) and quantitatively analyzed by means of an image analyzer. A scanning electron microscope (SEM) equipped by energy dispersive X-ray spectroscopy (EDS) has been used to study the fractured surfaces. Hardness profiles have been performed across the joints in order to verify the hardness variations. A total absence of secondary phases has been found on the joints due to the performing of a suitable solubilizing heat treatment after the welding process. The results have shown that the impact properties of the samples have been mostly affected by the different heat inputs; in some cases a partial welding penetration has been found.

Sign in / Sign up

Export Citation Format

Share Document