The Effect of Shielding Gas Flow Rate on Fiber Laser Welding of Boron Steel

During laser welding process, the ionized metal vapor from keyhole surrounding by molten metal mixes with the shielding gas and forms a plasma plume over the molten pool. The small amount of plasma plume is needed to react with molten pool by enhancing the absorption of laser energy thus increase the penetration. However, high amount of plasma will absorb the beam energy and this could decreases the penetration depth. The small wavelength of laser beam such as fiber laser, reported has less influence to plasma plume compared to bigger wavelength such as CO2 laser. However, even though using small wavelength laser, the laser beam with welding speed below 17mm/s had to go through the plasma plume over the molten pool. The suppression of plasma plume is highly influenced by shielding gas setup and flow rate. In this study, the effect of shielding gas flow rate (Argon) on CW and PW mode on low power fiber laser welding of Boron steel (22MnB5) was investigated. The observation of welding surface, width and depth were carried out. The width and depth pattern of CW and PW were slightly different. The range of 10-20L/min shows the widest width and 15L/min shows the deepest penetration for both welding mode

Predictors of enhancing human physical attractiveness: Data from 93 countries

People across the world and throughout history have gone to great lengths to enhance their physical appearance. Evolutionary psychologists and ethologists have largely attempted to explain this phenomenon via mating preferences and strategies. Here, we test one of the most popular evolutionary hypotheses for beauty-enhancing behaviors, drawn from mating market and parasite stress perspectives, in a large cross-cultural sample. We also test hypotheses drawn from other influential and non-mutually exclusive theoretical frameworks, from biosocial role theory to a cultural media perspective. Survey data from 93,158 human participants across 93 countries provide evidence that behaviors such as applying makeup or using other cosmetics, hair grooming, clothing style, caring for body hygiene, and exercising or following a specific diet for the specific purpose of improving ones physical attractiveness, are universal. Indeed, 99% of participants reported spending >10 min a day performing beauty-enhancing behaviors. The results largely support evolutionary hypotheses: more time was spent enhancing beauty by women (almost 4 h a day, on average) than by men (3.6 h a day), by the youngest participants (and contrary to predictions, also the oldest), by those with a relatively more severe history of infectious diseases, and by participants currently dating compared to those in established relationships. The strongest predictor of attractiveness-enhancing behaviors was social media usage. Other predictors, in order of effect size, included adhering to traditional gender roles, residing in countries with less gender equality, considering oneself as highly attractive or, conversely, highly unattractive, TV watching time, higher socioeconomic status, right-wing political beliefs, a lower level of education, and personal individualistic attitudes. This study provides novel insight into universal beauty-enhancing behaviors by unifying evolutionary theory with several other complementary perspectives

First report on the herpetofauna of Pulau Aur, Johor, West Malaysia

With the exception ofTweedie's (1983) account ofCalamaria lovii, published accounts on the herpetofauna of Pulau Aur, located 63 km off the south-east coast of peninsular Malaysia in the South China Sea did not exist prior to this report. The only species known from the island were based on the museum records ofLimnonectes blythii, Mabuya multi/asciata, Bronchocela cristatella, Gehyra mutilata, Varanus nebulosus and Ahaetulla prasina deposited in the Raffles Museum of Biodiversity Research. A short expedition to the island on 15-16 July 2001 yielded an additional 12 species, comprising 10 lizards and two snakes: Limnonectes blythii; Bronchocela cristatella; Cnemaspis cf. Nigridia; Cosymbotus platyurus; Cyrtodactylus consobrinus; Gehyra mutilata; Gekko monarchus; Hemidactylus frenatus; Dasia o/ivacea; Emoia atrocostata; Lygosoma bowring;;; Mabuya multi/asciata; Sphenomorphus scotophi/us; Varanus nebulosus; Varanus salvator; Ramphotyphlops cf. braminus; Calamaria lovii and Macropisthodon flaviceps

Lap Joint Dissimilar Welding of Aluminium AA6061 and Galvanized Iron Using TIG Welding

In this paper, aluminium AA6061-O and galvanized iron were lap-joined using tungsten inert gas (TIG) welding. The experiments were conducted using Si-rich filler metals ER4043 (Si 5 wt.%) and ER4047 (Si 12 wt.%). The mechanical properties and the microstructure of the samples were analysed using dye penetrant non-destructive tests (NDT), optical microscope observation and shear tests. All samples showed good quality joints, with Al-GI specimens showing better quality. Through optical microscope observation, the intermetallic compounds (IMC) of specimens using ER4043 fillers show a thin IMC layer ranging from 4 µm to 7 µm, compared to ER4047 samples which ranged between 20 µm and 40 µm. The shear tests show that the GI-Al group fractured at the IMC layer, while the Al-GI group fractured at the FZ-HAZ aluminium matrix. The highest shear strength value obtained was 89.82 MPa and 76.59 MPa for the Al-GI and GI-Al positions, respectively. It can be concluded that the GI-Al (galvanized iron on top and aluminium at the bottom) configuration with filler type ER4043 (Si 5 wt.%) has the optimum mechanical properties with a thin IMC layer and tensile strength of 76.59 MPa

Optimizing the pulse wave mode low power fibre laser welding parameters of 22Mnb5 boron steel using response surface methodology

Recently, high strength and lightweight components requirement in the automotive industry have intensified the interest of utilizing tailor welded blank (TWB) technology for boron steel. Furthermore, with greater demands for efficiency and productivity of laser-welded products, the pulse wave mode of laser welding has been proposed to replace the continuous wave mode. Hence, in this study, the effect of pulse wave mode laser welding parameters (i.e. peak power, pulse duration and pulse repetition rate) on the mechanical properties of 1.6 mm thick boron steel (22MnB5) was investigated. The response surface method (RSM) was used to develop models to predict the relationship between the processing parameters and tensile strength. Additionally, the optimal parameters combinations of input variables were identified showing superior joint strength. As a result of utilizing optimal combinations, a highest ultimate tensile strength value of 533 MPa was obtained while the fracture being restricted at the base metal. The most significant parameter was found to be peak power when compared with pulse duration and pulse repetition rate in determining the weld penetration due to the impact of applied thermal energy. Besides, the low error percentage of 4.26% for tensile strength indicated that the results predicted by RSM were very close to experimental values. The microstructure in the fusion zone was transformed into martensitic and despite austenite transformation from pearlite, not all ferrite grains were transformed into austenite in the heat affected zone. The optimized samples showed a remarkable increase in hardness from 200 Hv of base metal to that of 535 Hv in the fusion zone

Upcycling the barbeque grease into carbon nanomaterials

Carbon nanomaterials (CNMs) have been a remarkable material and impacted today's technology in various fields, such as enhancing agents for host material and environment-related applications. Green synthesis of CNMs gains attention as it requires low cost and less energy during the fabrications. In addition, the starting material is either environmental-friendly or a waste carbon compound that can be obtained from the household or catering industry. In this research, CNMs such as carbon nanotubes (CNTs) and graphitic carbon layers were synthesised using barbeque grease as carbon precursor via the chemical vapour deposition technique (CVD). The oil waste was analysed with gas chromatograph-mass spectrometry (GC–MS), and it showed that the oil waste contained a high amount of hydrocarbon chain such as pentadecane and 1-nonadecene, which decomposed into simple hydrocarbon bonding during the deposition and grew CNMs on the catalyst. SEM and TEM results showed that the CNTs with a diameter range of 42 ± 17 nm (outer) and 3.5 ± 0.5 nm (inner) were synthesised using the Ni catalyst. Raman and SEM revealed that the graphitic carbon layers with a D to G peak intensity ratio (ID/IG) is 0.9898 were fabricated using Cu foil as the substrate. This research aims to discover novel and low-cost carbon precursors for the CVD system, to produce high-quality CNMs