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The need for titanium and its alloys has led to a significant increase in commercial manufacturing, although this material’s poor tribological qualities have been a drawback. The present study was to determine the effect of laser-textured surfaces to enhance Ti6Al4V surface wear performance. The sample underwent laser texturing based on pre-set parameter values at 15 W power at a laser scanning speed of 200 mm/s with a frequency of 50 kHz. The surface morphological and topological profile of laser-textured Ti6Al4V was characterized with also the surface microhardness. A comparative appraisal of wear rate (WR) and coefficient of friction (COF) for related samples of as-received Ti6Al4V and laser-textured Ti6Al4V was performed under dry and oil sliding conditions. The results revealed that the formation of oxidation due to the frictional force and plastic displacement plays a role of abrasive to the laser-textured surface and may result in increasing the COF. The wear rate of the laser-textured surface of Ti6Al4V exhibited 88.31% improvement compared to the as-received Ti6Al4V in the dry sliding wear test. It was proved that Ti6Al4V could benefit from LST to gain effectively enhanced wear performance.

The use of lasers in surface engineering has recently made significant progress. The hydrophobic surface is commonly studied because of the application in various fields, including vehicles, aerospace, biomedicine, etc. Since these laser methods require many combination parameters, such as laser power (P), frequency (ƒ), scan speed (ʋ) and laser beam diameter (D), the effect of the parameters must therefore be investigated to produce the hydrophobic condition. This research tries to relate the laser power with the morphological properties and contact angle of the SS316L surfaces. Samples are subjected to laser texturing with different laser power settings. The surface is then characterised by surface roughness, and the contact angle is measured according to a specific time interval. The laser power output and energy density function on the surface and contact angle were investigated in these contexts experimentally. Surface roughness was defined and validated to show that the laser parameters' effect is effective and controllable. This study shows that the laser output intensity significantly contributes to regulating surface roughness and the substrate's wetting activity. The 18W and 24W laser outputs produce a spiked surface with various peaks that cause the surface to become hydrophobic over time because of the air-trap that happens in the valley.

The rapid advancement of the welding technology has simultaneously increased the demand for the online monitoring system in order to control the process. Among the methods that could be possibly used to assess the weld condition, an air-borne acoustic method grasps the attention from scholars due to its ability to provide a simple, non-contact, and low-cost measurement system. However, it is still lack of resources involving this subject in an attempt to deeply understand the emitted sound behaviour during welding especially when dealing with a complete deviation of a process parameter, welding types, workpiece material as well as the noise from the surrounding. This paper reviews the application of the acoustic method in monitoring the welding process. Specifically, this review emphasized the source of both structure-borne and air-borne acoustic during the welding process and the significance of applying the acoustic method in more detail. By focusing on the liquid state welding process, the scope of discussion converged on the arc and laser welding process. In the last part of this review, the potential future advancement of this method is pointed out before the overall conclusion is made.

Titanium alloys are widely utilized in laser heating applications. However, it has poor optical properties due to low laser energy absorption. Nevertheless, a higher energy absorption can be realized by modifying the surface profile through increasing the surface roughness. In this present work, the laser surface modification (LSM) process was carried out to increase the roughness on surface of Ti6Al4V titanium alloy. Subsequently, the surface characterization and surface roughness were analysed by using the 3D optical microscope. The effect of laser power on the increment of surface roughness was investigated. It was revealed that an increase in laser power during LSM process could increase the surface roughness. The result shows that, the surface roughness of titanium alloy increased 27 times when modified with the highest laser power (27W) compared to the gritted surface. Furthermore, the modified surface by LSM will be heated using laser radiation in order to analyse the effect of surface roughness towards laser heating temperature. Depending on the value of the power during laser heating, the maximum temperature measured could be increased 27% corresponding to a gritted flat reference surface.

Defects such as cracks can cause dangerous damage to the metal structure and may lead to structural collapses. Cracks can exist in various shapes and sizes where they can start to develop from small scale lower than 1 mm and spread to contribute to the complete fracture of components. Hence, early discovery and monitoring of any cracks in their early stage are crucial to prevent any sudden fatal accidents in the future. This work presents the study and detailed analysis of an ECT probe’s development based on AMR sensors to identify sub-millimeter surface cracks in galvanized steel plates. The probe consists of an excitation coil that induces an eddy current in sample plates and two AMR sensors that detect the differential eddy current-induced magnetic response. A phase-sensitive detection technique with a lock-in amplifier is used to evaluate the magnetic field distribution detected by the AMR sensors. The measured magnetic responses are classified to the depth, width, length, and complex shapes of artificial slits, and the probe is used to perform line scans and 2-D map scans above the slits’ positions. The probe was able to characterize slits with a depth and width as low as 210 and 50 µm, respectively, by using an excitation current of 4 mA at 1 kHz. The slit orientations that were perpendicular to the differential direction of the AMR sensors were clearly visualized, with their estimated lengths showed a good correlation with the physical slit lengths. In the future, the developed system can be expected to help towards the development of a more sophisticated crack detection system where real-time inspections can be realized and applied in various fields.

Pulse wave (PW) welding technique has become more adequate process to produce a deep penetration welding with smaller fusion zone and heat affected zone for automotive steel joint. A 1.6 mm thickness of N22CB boron steel from advance high strength steel (AHSS) type was welded by using PW mode from a low power Nd: YAG laser. The process parameters studied in this paper are pulsed energy, Ep, focal length, F, and welding speed, S. Bead-on-plate (BOP) welding was used in this experiment. The effect of parameters on the weld pool geometry was studied. Higher pulsed energy gives high weld penetration and higher weld width, contributing to the bigger weld pool size. Positive defocus position of focal length produces weld geometry with high penetration depth and smaller bead width compared to negative defocus position. Lower welding speed could produce deep penetration depth as the high heat input produced.

In an automated laser welding process, it is vital to provide a robust monitoring system which could estimate weld depth by in-situ basis as it could directly give feedback to the control system for further action. This paper presents the development of the model for estimating the weld penetration by the analysis of sound acquired during the pulse mode laser welding process. In achieving the aim, several sets of experiment with the variation level of the laser peak power and pulse duration have been done onto 22MnB5 boron steel plate in the butt-joined configuration. Simultaneously, the sound signal was acquired between 20 Hz to 12 kHz, which lies within the audible range, along the process. In a further step, several features including recently developed multi-lag phase space were extracted from the acquired sound. Specifically, the thresholding method based on localized crest factor was introduced in this study to reduce the influence of noise on the multi-lag phase space value. The most significant features which possibly be a predictive variable for the estimation model was identified using feature selection analysis prior to the model development process using multiple linear regression (MLR) and artificial neural network (ANN) method. The finding in this study shows that the multi-lag phase space, L-kurtosis and standard deviation were listed as the most significant features for model development as it linear combination responding well to the change in weld depth penetration. Combination of these three sound features with weld parameter such as laser peak power and pulse duration in model development yield better result. According to the result from model validation by using the data from another set of experiment, it was found that weld depth estimation model developed by ANN method recorded lower mean error as compared to the model developed by MLR method. Specifically, the mean error shown by the ANN model was 4.08% while 7.49% of mean error was recorded by the MLR model. Based on the results obtained in this study, it could be concluded that the weld penetration estimation model was possibly developed from the sound features extracted from the signal acquired during pulse mode laser welding process. Apart from promoting non-destructive, as well as in-situ quality monitoring method, this method also allows ones to develop the control system which responds to the feedback from the monitoring system to achieve greater control during the process.

This review comprehensively covers the research accomplished in the field of laser welding of biomedical devices and implant materials. Laser welding technology in the recent past has been ...

This paper elucidates the influence of dimple-microtextured copper substrate on the performance of Sn-0.7Cu solder alloy. A dimple with a diameter of 50 µm was produced by varying the dimple depth using different laser scanning repetitions, while the dimple spacing was fixed for each sample at 100 µm. The dimple-microtextured copper substrate was joined with Sn-0.7Cu solder alloy using the reflow soldering process. The solder joints’ wettability, microstructure, and growth of its intermetallic compound (IMC) layer were analysed to determine the influence of the dimple-microtextured copper substrate on the performance of the Sn-0.7Cu solder alloy. It was observed that increasing laser scan repetitions increased the dimples’ depth, resulting in higher surface roughness. In terms of soldering performance, it was seen that the solder joints’ average contact angle decreased with increasing dimple depth, while the average IMC thickness increased as the dimple depth increased. The copper element was more evenly distributed for the dimple-micro-textured copper substrate than its non-textured counterpart.

The pulse wave (PW) mode is an excellent replacement for continuous wave (CW) mode f laser welding in the tailor-welded blank (TWB) application for the automotive ndustry. Due to its ability to produce higher peak power in low power laser pulse mode, he weld penetration and high weld quality can be achieved similarly to the utilization of very high power laser of CW mode. This present work was carried out to investigate the ffect of pulse laser welding parameters of a dissimilar thickness of boron steel for the TWB application. Low power fibre laser with 200 W average power was chosen in this xperimental work. Response surface method (RSM) was used for the design of xperiment (DOE) by applying Box-behnken design (BBD) since there were three rocess factors involved. The process factors are peak power (PP), welding speed (WS) nd focal position (FP) and tensile strength is the response for the weld joint. The metallurgical analysis was conducted at the cross section of sample possessing highest nd lowest tensile strength. Boron steel was successfully welded by using low power fibre aser with PW mode in butt joint configuration. It was found that the highest tensile trength possessed fracture located at the base metal, which is convincing the strength of he joint. For microstructure, finer grain produced at the centre of the fusion zone (FZ) ompared to the FZ near the transition line which produced coarser and medium grain. Finer grain size in FZ contributes to the higher microhardness value and tensile strength f the joint compared to the BM region.

The need for better thermal–hydraulic performance of heat exchangers remains the primary reason for further improving the design of heat exchanger. Various investigations have been carried out on the design and performance of fin-and-tube heat exchangers (HEs). Different HE designs were made available that can enhance the heat transfer and reduce the pressure drop. Recently, existing heat exchangers are either have been improved or replaced by newly emerged heat exchangers with better thermal–hydraulic performance. In this review, fin-and-tube HEs’ thermal–hydraulic performance investigation methods and their detailed flow and heat transfer analyses results are summarized. This review also critically surveyed the major heat transfer enhancers and their configuration, geometry and material type effects on thermal–hydraulic performance. Furthermore, a summary of both the theoretical and experimental studies on HEs’ performance is made. Also, the effects of tubes dimension, arrangement and number rows on HEs’ performance have been discussed. Furthermore, different ways to optimize the geometrical and process parameters of the fin-and-tube HEs were studied, considering the heat transfer enhancement, pumping power, size of the heat exchanger, and other economic factors. Finally, future studies and perspective in the field of fin-and-tube HEs are included.

Many ongoing studies have proven that statistical features extracted from the acquired sound during a laser welding process significantly yield some pictures on the weld condition, including weld geometry. However, a considerable amount of studies has underlined the use of common statistical features in which they are restricted to some limitations when dealing with non-stationary random sound signal. In the present study, the main aim is to study the correlation between the L-statistical features trend of the sound amplitude distribution with respect to the change in weld geometry during pulse mode laser welding compared to common statistical features. In an attempt to achieve this goal, a pulse mode laser welding was subjected to 22MnB5 boron steel with variations in the peak power, pulse width, and focal length. Meanwhile, the sound signal was acquired during the process, with standard deviation, interdecile range, mean absolute deviation, L-Cv (scale), and L-kurtosis extracted from the analysis. The degree of correlation between these statistical features and weld geometry was compared from the R-square value. According to the reported results, L-kurtosis yielded the strongest correlation with both weld penetration depth and bead width compared to the remaining five statistical features. This showed that the use of L-statistical features was significant to improve the correlation between sound signals and weld geometry.

In present work, an attempt was made to investigate the effect of alumina nanoparticle (ANP) reinforcement to the wetting and mechanical properties of adhesively bonded aluminum alloy with epoxy adhesive. ANP of 13 nm size in 0–2 wt% concentration was utilized to be incorporated into two components epoxy adhesive to evaluate its effect on wetting behaviour and tensile shear strength. The addition of ANP results in improved contact angle and spreading area of the adhesive. The inclusion of ANP content up to 1.0 wt% demonstrates approximately 54.2% improvement of tensile shear stress as compared to its pristine epoxy counterpart. In this work, it is observed that regardless of ANP concentration, fractured specimens demonstrate the combination of both adhesive and cohesive fracture (CF) region, with highest CF region observed at 1.0 wt% ANP reinforcement. From thermomechanical analysis results, at 30 °C significant increment of both storage and loss modulus up to 68.3% and 17.3% respectively is achieved with 0.5 wt% ANP inclusion.

In the current research work undertaken, an oxide film was grown by performing hard anodizing process on a pure aluminum layer deposited by PVD magnetron sputtering process on AA7075-T6 alloy. The corresponding tribo-mechanical properties were evaluated and compared with those of the base alloy. The dry sliding wear experiments were carried out to investigate wear resistance of anodized AA7075-T6 against the AISI SS316 counter-body by means of a reciprocating tribo-testing setup. The hardness of AA7075-T6 after the anodizing process exhibited an enhancement of about 1.94 times. Results revealed that the wear of anodized coating was exceptionally less when compared with the substrate. Based on morphology and chemistry changes of worn-out surfaces and debris, it was determined that severe abrasive and oxidative wear was the primary wear mechanism for AA7075-T6. The anodizing process increased the friction coefficient from 0.33 to 0.46 but reduced the wear severity by altering the wear mechanism into mild polishing and abrasion. Anodizing enhanced the wear resistance of AA7075-T6 to about three times, and the wear rate decreased to around 4.3 times.

Early detection of defects in metallic components used in infrastructure is crucial to ensure their safety and reliability. This paper presents a development of a small eddy current testing (ECT) probe for evaluation of sub-millimetre surface defects. The ECT probe is developed in a planar differential using sensitive anisotropy magnetoresistance sensors, and the signal amplification is achieved by a home-made instrumentation amplifier. The developed ECT probe is evaluated by performing phase sensitive measurement of the magnetic responses of sub-millimetre surface slits at the excitation field of 200 Hz and 10 kHz. Compared to the real component of the magnetic response, the imaginary component can be used to identify the existence and position of the slits based on the signal intensity change caused by the induced eddy current. The spatial distribution of the magnetic response measured by the ECT probe can be used to estimate the dimension of the slit. It is expected that the developed ECT probe can be utilised for assessment of sub-millimetre surface defect.

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.

Laser surface modification is an emerging process that can produce texture on a work surface and effectively enhance surface topography while altering surface roughness. Laser surface modification is a sensitive process that depends on various laser processing parameters such as power, scanning speed, hatching distance. The significance of this work is to examine the influence of hatching distance on the surface characteristic of 2205 duplex stainless steel samples. The surface transformation and variation of the surface roughness properties of the materials were examined. The hatching distance was varied from 0.1 to 0.005 mm. Results indicate that, as the hatch spacing decreases, the overlap of laser track increases, thereby resulting in a decrease of surface roughness. Meanwhile, with the increase of hatch distance, the clear overlay tracks were transformed to irregular wavy surface. The best hatch distance parameter obtained was 100 μm that resulted in the highest roughness of 8.45 μm. Experimental results illustrate that, when the optimum hatch distance of 100 μm was adopted, the polished smooth surface of 2205 duplex stainless steel with initial average roughness value of 0.19 μm increased by 42 times of the polished surface roughness. A strong correlation between hatching distance and roughness was established in 2205 duplex stainless steel. High depth of the altered surface topography and increased roughness were linked to higher levels of hatching distance.

Defects in steel structures are one of the major problems that may affect the functionality of the structure. Thus, the detection of the defects is fairly crucial to prevent any unwanted accident from occurring. Nondestructive Testing (NDT) is a group of methods that is widely used to detect those defects, especially cracks. This paper will be focusing on the detection of cracks (artificial slits) by using the Magnetic Flux Leakage (MFL) technique in the magnetic method of NDT. A non-saturated differential MFL probe consists of two AMR sensors has been fabricated for the detection of front as well as backside slits. A measurement system which incorporates the developed probe attached on an XY-stage, a set/reset circuit, an amplifier circuit, a DAQ card, and PC is constructed where an XY-stage controller and a digital lock-in amplifier are developed with the implementation of LabVIEW. Then, the developed MFL probe’s performance is evaluated by running several line scan measurements on a 2-mm galvanized steel plate sample engraved with artificial slits with depths that varies from 1.0 to 1.6 mm with variable excitation frequencies. The results show promising output where the slits could be successfully detected and its position could be further estimated. Furthermore, the correlation between the slit depth and difference (delta value) between the signal peaks and troughs could also be founded. Consequently, the optimum excitation frequency can be determined by plotting a graph of the slope of trend line of the delta values versus the frequency.

This study performs an analysis of a small eddy current probe configuration based on differential anisotropic magnetoresistance (AMR) sensors for characterization of small surface defects in galvanized steel plates. Owing to the advantage of the AMR sensor, the system of eddy current testing (ECT) with the AMR sensor has a huge benefit to detect sub-millimeter defects in steel structures. In this study, an ECT probe is developed by using AMR sensors to perform crack detection in 2-mm galvanized steel plates with regards to the depth of artificial slits where the ECT probe is scanned above the slits’ area. The signal that is detected by a lock-in amplifier is investigated with different frequencies of an excitation field. The line-scanned of signal intensity shows a clear intensity change at the crack area. This signal depends on the depth and frequencies. Finally, a correlation between depth and detected signals is clarified with respect to different frequencies.

Tool design plays an important role in the development of dissimilar friction stir welding. This paper presents a design study of the welding tool through investigating the effect of pin flute radius during the friction stir welding of dissimilar AA7075-T651 and AA2024-T351 aluminum alloys. Five pin tools with different flute radii (0, 2, 3, 6, and ∞ mm) were inspected under 900 rpm spindle speed and 150-mm/min traverse rate, taking the position of base materials on the advancing and retreating sides of weld into account. The metallographic analysis and tensile properties of the welding joints were presented and discussed. The results clarified that the flute radius affects the material flow pattern and weld quality. The strongest joint was produced using the welding pin tool with a flute of radius equals to that of the pin, regardless of the relative materials position.

Demands of tailored weld blank application on press hardened materials such as boron steel have given interest in the process parameter study of laser welding. The pulse wave mode of laser welding produces high peak power, replacing the continuous wave mode which could lead to wider applications. Due to complications on the process parameter of PW mode, the study of parameter effect is needed. In this paper, the effect of PW welding parameters on weld geometry of boron steel using Fibre laser is presented. Pulse overlap (PO), peak power (PP), pulse duration (PD) and pulse repetition rate are the common process parameters for PW mode used in this study. The bead on plate welding was conducted on uncoated boron steel and observation on width and depth of penetration was done. Based on the results, the higher PO produced deeper penetration and also a bad weld appearance. The effective pulse energy and effective peak power density were the result of the actual condition in pulse seam weld related with overlapping index generated from PO condition. The PP and PD were the related parameters that affected the energy of the beam, giving a significant effect on weld width and penetration. The energy of the beam showed the significance on weld geometry in low peak power laser application and the value will increase with the increase of PD. In contrast, PRR had no significant effect on weld geometry. The constant pulse overlap parameter produced constant energy applied for each pulse which led to no effect on weld geometry.

This study highlights the scratch adhesion failure characterization and tribo-mechanical properties of physical vapor deposited (Cr, Ti) N coating on AA7075-T6 by using magnetron-sputtering technique. The surface morphology, microstructure and chemical composition of CrTi/CrTiN film were inspected by an optical microscope, scanning electron microscope (SEM) incorporated with energy dispersive X-ray spectroscopy (EDX) in addition to focused ion beam milling. The coating to substrate critical load of about 1261 mN was obtained, by employing coating deposition parameters of; DC power (300 W, RF power (200 W)), temperature (300 °C) and nitrogen flow rate (6%). Failure adhesion characteristics exhibited initial arc-tensile cracking followed by chipping and spallation that led to complete coating failure at Lc3. The tribo-mechanical aspects were evaluated by a pin-on-plate reciprocating testing unit, which showed a lower friction coefficient of 0.36 for CrTiN as compared with 0.43 for AA7075-T6. Subsequ...

The effect of heat treatment on the microstructure and mechanical properties of 1.6-mm-thick boron steel welded by using gas metal arc welding was investigated. The microstructure and mechanical properties of welded boron steel were determined before and after heat treatment. The heat treatment process was conducted according to manufacturer recommendation for optimum outcome. In results, the microstructure of heat treated specimen was completely transformed to martensite. The soften region that was detected and caused fracture of tensile test is located. EDX analysis found that boron element was concentrated at heat-affected zone. Fractography on heat-treated samples shows an intergranular fracture at heat-affected zone because of microvoid existence at grain boundaries. Consequently, this fracture decreased sample strength and promoted fracture propagation.

The mechanical fatigue behavior of (PMMA) poly(methacrylate) under shoot peening was investigated under room temperature and stress ratio R =−1 using rotating bending tests. The fatigue life of specimens was increased up to 5 min. Shot peening test (SPT) and then it reduced. Also at the same SPT (5 min) the endurance fatigue limit was raised by 300% compared to the dry fatigue. The hardness and roughness were increased when the SPT increased. The control factor which affects the fatigue life was the roughness after 5 min, shot peening.

Friction stir welding of dissimilar aluminum alloys has become an important application in the modern industries. Joint strength is a major consideration in this advanced technology. This paper presents an attempt made to improve the weld tensile strength by controlling the temperature distribution during the joining process. High-strength AA7075-T651 and AA2024-T351 aluminum alloys were friction stir welded using different backing and clamping materials. The tool rotation rate was preliminarily investigated to estimate the optimal spindle speed. Next, three composite backing plates and clamping systems were tested in conjunction with varying levels of traverse speeds and materials position. The transient temperatures were experimentally measured at different distances from the welding line. Asymmetric temperature distributions were observed with maximum records on the advancing side of the weld. Moreover, the influence of backing and cover materials on the joint strength was found to be varied with the applied level of the welding traverse speed. Based on these results, an idea to use asymmetric system of backing and cover materials was inspired. This system assisted to improve the temperature distribution and resulted in a sound weld with higher tensile strength. The detailed results of this work were discussed and the main outputs were outlined in the conclusions.

The aim of this research paper is to study the effects of cooling rates on microstructure and mechanical properties of Sn3.8Ag0.7Cu solder alloy prepared through powder metallurgy (PM) method. They were cooled by different cooling medium such as slow (furnace cooling), normal (air cooling) and fast (water cooling) which was 0.0076°C/s, 0.73°C/s and 31.14°C/s, respectively. Characterisation for each sample was conducted to examine the intermetallic compound formation and solder shear strength. Result indicated that faster cooling rates decreased the IMC thickness but reduced the solder joint strength due to distribution of melted solder on Cu board. This study found that the shape of Cu6Sn5 and Ag3Sn changed according to cooling rates either at the interfacial or in the solder matrix. The study on comparison between three different cooling rates onto properties of Sn3.8Ag0.7Cu solder alloy prepared by PM method is still unknown and the current findings are still unclear. Thus this research would be the fundamental study to investigate the effects of cooling rates onto behaviours of the solder alloy. It is believed that more attentions will be shown onto this superior topic to increase the level of promising reliability of solder alloy in industry and marketplaces.

Nowadays, brazing has been widely used in many industries, especially in the automotive application. The brazing process is introduced as it can be used to join the different metals together without melting the parent material. In this present study, furnace brazing and laser brazing of Ti-6Al- 4V titanium alloy and 316 L stainless steel (SS) with silver-based, BAg 8-1.5Ti filler metal were studied. There are significantly different between furnace brazing, also known as conventional brazing method and laser brazing in terms of joining strength and microstructure reaction. Furnace brazing was performed at 870°C and 880°C with 30 minutes of heating duration. Meanwhile, laser brazing was performed using a 200Watt continuous wave laser with varying laser power. Both of brazing method was conducted with a vacuum pressure of 3×10−3 Pa. Besides, to maintain the accuracy of the temperature measurement of laser brazing, an infrared thermometer is used. The tensile test was conducted to analyse the mechanical properties. The cross-sections of the brazed joints have been examined using an optical microscope. The brazed joints of the furnace brazing show an average tensile strength of 55.89 kPa for 880°C and 43.16 kPa for 870°C. Nonetheless, the maximum tensile strength of laser brazed joints was 27.95 kPa, which is lower than furnace brazed joints.

Due to their lightweight and ease of manufacturing, fibre-reinforced composites are replacing metals in many heat exchanger applications. However, their heat transfer dissipation performance is not investigated in detail. This paper aims to study experimentally the heat transfer performance of fins made from fibre reinforced composites in compact heat exchangers. Thin fins were manufactured from reinforced fibre composites by the hot pressing technique. The fins have dimensions of 11.5 cm wide and 11.5 cm long. Five different airflow velocities with fixed water flow rates were considered in the analysis. The temperature distribution inside the tube was measured at eight different points using a K-type thermocouple. The results showed that the water temperature at the outlet section was the highest at the lowest airflow velocity. Moreover, the air-side heat transfer coefficient increased along the tube length at all airflow velocities. The comparable heat transfer performance results make the fibre reinforced fins a good choice in the compact fin-and-tube heat exchanger.

Laser brazing uses a filler metal for joining without melting the base material. This process is a versatile joining technique for a wide range of applications including automotive, aerospace, and medical field because of the ability in joining dissimilar metal and resulted good quality in surface’s joint. This study consists of aluminium alloy of AA6061 and AA7075 as a base material with aluminium based ER5356 as a wire filler. Laser brazing was performed using 1.2 kW of laser power, while wire filler was let to be prefixed without using the wire feeder because of using the existing laser welding machine. Microstructure of the joints were studied using 3D measuring laser microscope OLS5000. Besides that, mechanical properties of the joints were evaluated by performing tensile test and hardness test. Microstructures of the brazed joints show the differences in the grain structure followed by the difference’s hardness value on each region. The brazed joint shows the average ultimate tensile strength reached 154.71 MPa which was 50% of joint efficiency. However, there is porosities at the fracture surface of the joint.

In this research, the laser colour marking process was carried out to determine the formation of colour on surface of SS304L stainless steel. The pulse laser nanosecond (1064nm) was used to irradiate the SS304, resulting in the formation of various colour permeating on the sample surface. The surface characterization and surface roughness were analysed by using the 3D optical microscope. The effect of laser processing parameters such as hatching distance, pulse width, and defocusing distance on the evolution of surface colours were investigated. The results show that a thin oxide film was essentially formed that resulted in the formation of four different colours. Each colour exhibited a different surface texture and surface roughness implying the effect of parameters significantly affects the surface characteristics. Grey colour formed registered the highest roughness (Rz) of about 3.5 microns followed by a decreasing roughness trend for blue, purple and green respectively.

The pandemic situation demand the construction player need to consider to re-evaluate architecture design. The issue of shortage of skilled workers due pandemic and method of traditional construction involving longer period and close contact among labours questioned in many countries. Therefore, industrial building system (IBS) or modular construction involves using pre-made modules created in a factory and brought to construction sites for assembly is one of method is recommended to overcome the issue during pandemic period. Nevertheless, The Malaysian IBS manufacturing player faced the difficult to achieve economies of scale due to higher capital cost and this problem caused by high operational cost in manufacturing. In marketing a product, sales expense is crucial to ensuring that a product can be sold in large quantities. In this study, sales expense variables among the established the cost control parameter required by IBS manufacturer that seeking for lower and stable market prices will be discuss in detail. To achieve the study objective. Thus, in this study, six (6) case studies from reliable data in the theme competitive pricing will be selected in this quantitative study. In a nutshell, this study explores China’s perception in term of competitive pricing of IBS components as per recommendation by many scholars. Using semi structure measurement instrument, the recorded data gained in this study later, transcribed using Atlas. Ti software. Also, the study is expected might help the Malaysian IBS manufacturer to realise the sales-related expenses strategies that need to be invested that might boost IBS demand in their enterprises.

Friction stir welding (FSW) of dissimilar alloys and materials is becoming progressively essential as it permits to take the benefits of both materials. Tensile strength is a measure of the weld quality, which mainly depends on machine variables and tool design. In this paper, FSW of dissimilar AA7075-AA6061 aluminium alloys was studied with respect to the welding speeds (rotational and axial), tool tilt angle and tool geometry by the response surface methodology (RSM) with central composite design (CCD). A reduced second-order polynomial equation was successfully developed and validated to adequately fit the observed results of the ultimate tensile strength (UTS). Respectable fitness and well agreement between the experimental and calculated values with an elevated regression coefficient and low deviation were detected for this model within the range of the operating variables. Five tools with concave shoulders and different probe profiles (cylindrical and tapered, smooth and threaded, flatted and non-flatted) and a self-designed backing plate and clamping system were fabricated for this study. It was found that the welding tool with a threaded truncated cone pin and single flat results in a sound weld with higher tensile strength, wide nugget area and smooth surface finish.

Detection of severe defects such as porosity underneath the weld bead during the welding process is vital during installation of a gas pipeline network because such defects might lead to fatigue crack. In this study, the work associated with detection of porosity through analysis of the acquired arc sound is presented. Air-borne acoustic signal was acquired during the metal inert gas welding process on API 5L X70 gas pipeline steel. Then, the acquired signal was analyzed using Hilbert Huang transform (HHT), which uses empirical mode decomposition for the purpose of filtering unrelated-to-damage signal components, and Hilbert spectral analysis to obtain the energy-frequency-distance plot. Results showed a significant energy amplitude pattern at the region where both surface- and subsurface-pores existed. Thus, the application of HHT analysis to the acquired arc sound signal has significantly assisted in identifying hidden information that is related to the existence of defects. This finding would enhance the development of an online welding defect detection system during the welding process.

The aim of this research is to predict the tensile strength of the dissimilar aluminium joint by optimizing the parameters in metal inert gas (MIG) welding between aluminium alloys AA6061-T6/AA7075-T6. In this study, the box-behnken design technique and mathematical model were developed by Response Surface Methodology (RSM). Statistical tools such as Design of Experiments (DOE), Analysis of Variance (ANOVA), and regression analysis were used to develop the relationships. Dissimilar aluminium of AA6061-T6 and AA7075-T6 were butt-welded by using MIG with the ER5183 filler. The highest ultimate tensile strength (UTS) of the joint obtained was 178.63 MPa.

The formation and growth of the intermetallic were frequently discussed since lead free solder took place replacing the lead solder. However, the effect of multiple reflow process on the intermetallic morphology that was subjected to aging still needs further investigation. Thus, this study aimed to investigate the effect of second reflow towards the intermetallic compound formation and growth. Two types of surface finishes were used such as Immersion Tin (ImSn) and Electroless Nickel Immersion Gold (ENIG). Both test boards were reflowed once with Sn-3Ag-0.5Cu at the temperature of 225 °C and soaking for 8 seconds. Then, they were reflowed again at the same temperature for 25 minutes prior to an isothermal aging process for 250, 500, 1000 and 2000 hours at the temperature of 150 °C. The ProgRes C3 IM7200 Optical Microscope and ImageJ were used for the microstructural study, which includes morphology and thickness. Results indicated that IMC thickness formed between solder and ImSn surface finish increased significantly with 1.28 µm incremental when exposed to the second reflow. Whereas the IMC thickness of ENIG surface finish was increased for up to 0.15 µm. In addition, ENIG showed higher activation energy as compared to ImSn.

This study focuses on the effect of pin taper tool ratio on friction stir welding of aluminum AA7075. Two pieces of AA7075 alloy with thickness of 6 mm were friction stir welded by using conventional milling machine. The shoulder diameter used in this experiment is fix 18mm. The taper pin ratio used are varied at 6:6, 6:5, 6:4, 6:3, 6:2,and 6:1. The rotational speeds that were used in this study were 1000 rpm, 1200 rpm and 1400 rpm, respectively. The welding speeds used are 60 mm/min, 80 mm/min and 100 mm/min. Microstructure observation of welded area was studied by using optical microscope. To evaluate the mechanical properties of this specimen, tensile test was used in this study. Welded specimens using taper pin ratio 6:2 shows higher tensile strength compared to other taper pin ratio up to 197 MPa. Moreover, taper pin ratio 6:1 showed better tensile test compared to taper pin ratio above 6:3. The optimum parameters were found to be taper pin ratio 6:2 with 1000 rpm of rotational speed and 60mm/min welding speed.

Innovative welding techniques allow for the fabrication of light, high-specific-strength, and fuel-saving Al and Mg alloys for use in transportation industries. Furthermore, these techniques have minimal detrimental impact on the environment. However, the poor mechanical properties of joints resulting from the formation of brittle Al m Mg n intermetallic compounds are key barriers to joining Al and Mg alloys. To date, a proper solution to this problem has not yet been provided. The aim of this research was to investigate the mechanical and metallurgical properties of the joint between AZ31B and A7075-T651 alloys welded by a new technique called gas metal arc plug welding method. ER5356 aluminum wire was used as a filler. The yield and ultimate tensile strengths as well as impact toughness of the joints were measured. The fracture surface was investigated by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The maximum ultimate tensile strength and impact toughness of the joints were 89 and 84 % of those of the AZ31B parent alloy, respectively. Generally, the joints failed in the ER5356 nugget, whereas some failed in the AZ31B alloy. No fracture was observed in the A7075-T65 alloy. Brittle fracture mechanism was observed for all the joints. In conclusion, the proposed welding technique can allow for better mechanical properties of joints for dissimilar welding of aluminum and magnesium alloys.

Purpose This paper aims to study the effect of aging and cooling rate on the reliability of the solder joint using electroless nickel boron (EN-Boron) as a surface finish in the electronic packaging area. Design/methodology/approach EN-Boron was plated on a Cu substrate through electroless plating method. This process was followed by reflow soldering of Sn–3.0Ag–0.5Cu solder alloy on metallized Cu substrate to form a joining. Then, the specimens were cooled using different cooling mediums such as air (slow cooling) with 15.7 °C/min and water (fast cooling) with 110.5 °C/min. After that, the specimens were subjected to isothermal aging at 150°C for 0, 250 and 1,000 h. Finally, they went through a lap shear test following ASTM D1002. Optical microscope and scanning electron microscopy were used for intermetallic compound (IMC) characterization. The type of IMC formed was confirmed by field emission scanning electron microscope-energy-dispersive X-ray spectroscopy (FESEM-EDX). Findings The results showed that the IMC type changed from the combination of Ni3Sn4 and (Ni, Cu)3Sn4 after reflow soldering into fully (Ni, Cu)3Sn4 when aged for 1,000 h. The formation of (Ni, Cu)3Sn4 and Cu3Sn underneath the IMC layer played a role in reducing the shear strength of joining. Overall, water cooling was reported to provide higher shear strength of solder joint compared to air cooling medium. Originality/value The shear strength when using EN-Boron as the surface finish is comparable to the surface finish conventionally used.

Surface finishes on copper pads have been known to be one of influential factor in the solder joint quality. This due to the difference in interfacial reaction and intermetallic compound formation on solder pad was strongly influence by the type of surface finishes. Deposition times during immersion plating process on copper pads are important as the thickness of coating will decide several properties of surface finish, such as wettability during soldering process. Thus, this study aims to investigate the effect of deposition time of immersion gold coating on wettability of the surface finish and how it affect the formation of intermetallic compounds on solder joint. In this works, deposition time of copper pads in immersion gold solution were varied from 3 minutes up to 15 minutes. The thickness of immersion gold layer that form on Cu pads were then measured using Scanning Electron Microscopy (SEM). As the main objective of this study is to study the effect of deposition time during immersion plating process towards solder joint, the pads were reflowed along with Sn-3.0Ag-0.5Cu solder in furnace under temperature 250 °C for 25 minutes. Then, the cross sections of the solder joints were examined using optical microscope in order to measure the wetting angle and thickness of intermetallic compound formed; which acceptable value in industrial area, should be below 40 ̊ and below 4μm as reflow respectively.

The performance of Thermo-Electric Generator (TEG) is negatively affected by heat sink lack of design. The heat pipe heat sink (HP-HS) has the best performance compared to other conventional cooling systems which uses TEG. In medium temperature range below 300 °C, HP-HS is the most appropriate heat exchanger of the TEG. However, the effect of some parameters of fin space, fin length, fin height, fin materials and optimum geometry of the cold side of the TEG HP-HS under forced convection (FC) has not been fully studied. The objective of this paper is to conduct an analytical and statistical study on these parameters effect on the performance of the TEG. In addition, this paper determines the optimum geometry of HP-HS and materials of aluminum (AL) and copper (CO) at 250 °C of heat source temperatures. Central composite design model (CCD) has been used to design the experiments using response surface methodology (RSM). The multi-objective optimization using RSM is applied to determine the optimum geometry of HP-HS in terms of maximising the TEG power output (P), TEG efficiency (η), and minimising HP-HS cost ($). Compared with the literature, the results showed an improvement in TEG performance. The maximum P and η after optimization were 9.6 W and 3.3%, respectively. The percentage difference of TEG efficiency (η) compared with best previous results were, 18.78%. In addition, the CO HP-HS was found to be preferred over AL, because of its lower $/P, at 7.57 USD/W, as compared to AL, at 8.74 USD. Finally, this study shows an improvement in HP-HS cost; a reduction of 29% was achieved compared with the estimated HP-HS cost in literature.

Since its inception, laser beam welding as a high-quality fusion joining process has ascertained itself as an established and state of art technology exhibiting tremendous growth in a broad range of industries. This article provides a current state of understanding and detailed review of laser welding of titanium (Ti) alloys with corresponding dissimilar counterparts including steel, aluminium, magnesium, nickel, niobium, copper, etc. Particular emphasis is placed on the influence of critical processing parameters on the metallurgical features, tensile strength, hardness variation, percentage elongation and residual stress. Process modifications to improve dissimilar laser weldability by virtue of techniques such as laser offsetting, split beam, welding-brazing, hybrid welding and materials modifications by means of the introduction of single or multiple interlayers, fillers and pre-cut grooves are exploited. Detailed and comprehensive investigations on the phenomena governing the formation and distribution of the intermetallic phase, material flow mechanisms, their relations with laser parameters and their corresponding impact on the microstructural, geometrical and mechanical aspects of the welds are thoroughly examined. The critical issues related to the evolution of defects and the corresponding remedial measures applied are explored and the characteristics of fracture features reported in the literature are summarised in thematic tables. The purpose of this review is tantamount to emphasise the benefits and the growing trend of laser welding of Ti alloys in the academic sector to better exploit the process in the industry so that the applications are explored to a greater extent.