Proceedings of the Sustainable Concrete Materials and Structures in Construction 2020

Seminar on Sustainable Concrete Materials and Structures in Concrete Construction 2020 was held virtually for the first time on 24 August 2020. This event was organized by the Faculty of Civil Engineering and Built Environment (FKAAB), Universiti Tun Hussein Onn Malaysia (UTHM) in collaboration with Concrete Society of Malaysia (CSM) and Civil Engineering and Built Environment Postgraduate Society, FKAAB (CiBPS). The theme of this seminar is Toward Sustainable Green Concrete. This seminar marks the first collaboration between these three organizations

Review on the possible tool materials for friction stir welding of steel plates

The friction stir welding (FSW) process is mainly used in industrial applications for joining low melting temperature materials such as aluminium and magnesium. FSW has many advantages in comparison with conventional fusion arc welding. Therefore the interest to use this technique for joining steel plates has grown. However such usage is still limited because of the lack of adequate tool materials. This review gives an overview of possible tool materials for FSW of steels focussing on tungsten, tungsten carbide, pcBN and a few ultra-high temperature ceramics

Social emotional skills (SES) among lecturers in relation students performance

Social emotional skills (SES) of a lecturer are considered to play a vital role towards student performance. Despite of the fact, when it comes to Technical Vocational Education and Training (TVET), very little research is found on the importance and implementation of these skills. This research therefore determined the level of TVET lecturers’ SES based on lecturers’ and students’ perspective, their relationship with student performance and difference in the level of SES between lecturers in education faculty and in engineering faculty. A case study method with quantitative approach was employed at Universiti Tun Hussein Onn Malaysia (UTHM). A total of 99 lecturers and 373 of final year bachelor degree students from an education and an engineering faculties were involved in this study. They were selected using purposive sampling and total population sampling techniques. Data were collected using two sets of questionnaire, Empathy Quotient (EQ) to measure empathy and Teacher Interpersonal Self-efficacy Scale to measure self-efficacy. Findings showed that lecturers have high level of SES from lecturers’ and students’ perspective. Furthermore, the results of Mann Whitney U Test indicated statistically significant difference the perspective of lecturers and students. However, there was no significant correlation between lecturers’ SES with students’ performance. Nonetheless, lecturers’ self-efficacy for classroom management had statistically significant relationship with students’ performance. Meanwhile, there was also significant difference found in the level of lecturers’ social emotional skills between both faculties. It is concluded that external related reliable feedback is important for lecturers to get to know about their level of SES. SES have a vital role towards students’ performance and that lecturers with professional education background are more effective than lecturers with engineering background. It is hoped that this study could enhance the awareness of TVET institutions in SES as such could help the development of better skill workers in future

Pulsed laser micro ablation of polycrystalline cubic boron nitride

Polycrystalline cubic boron nitride (PcBN) is the second hardest material after diamond. Because of its unique properties, PcBN is extensively used as a cutting tool material for the machining of hardened steels. Pulsed laser ablation (PLA) offers the possibility to generate tailored microgeometries on PcBN tools and can thereby increase tool performance. However, the thermal response of PcBN materials to the laser ablation and the laser effeciency in laser machining is not known in dependency of certain PcBN grade characteristics. In this paper the influence of different laser sources in the short and ultrashort pulse duration regime is investigated for a wide number of PcBN grades. Thermally induced surface alterations are examined in detail and connected with the functional performance of the material. It could be shown that a careful parameter definition is crucial for enhancing the performance of laser prepared PcBN cutting tools. © 2020 The Authors. Published by Elsevier B.V

Comparison between friction stir and submerged arc welding applied to joining DH36 and E36 shipbuilding steel

With the impending development of FSW tools for steel with useful lifetimes, attention has turned to the mechanical properties of the welds that can be made in a range of industrially significant steels. This work reports on a comparative study undertaken to examine the use of friction stir and submerged arc welding on DH36 and E36 shipbuilding steels. The study made an assessment of the distortion induced in fabricating plates by the two welding techniques, and provides initial comparative data on weld tensile strength, toughness and fatigue life. In each case, friction stir welding was shown to outperform submerged arc welding

Effect of Cutting Conditions on Machinability of Superalloy Inconel 718 During High Speed Turning with Coated and Uncoated PCBN Tools

Inconel 718, an efficient superalloy for energy and aerospace applications, is currently machined with cemented carbide tools at low speed (vc≈60 m/min) due to its unfavorable mechanical and thermal properties. The article presents results of superalloy machinability study with uncoated and coated PCBN tools aiming on increased speed and efficiency. Aspects of tool life, tool wear and surface integrity were studied. It was found that protective function of the coating, increasing tool life up to 20%, is limited to low cutting speed range. EDX and AFM analyses suggested dominance of chemical and abrasive wear mechanisms. Residual stress analysis has shown advantageous compressive surface stresses

OPTIMIZATION OF CUTTING CONDITIONS FOR SUSTAINABLE MACHINING OF SINTERED POWDER METAL STEELS USING PCBN AND CARBIDE TOOLS

Powder metals are becoming a popular choice in the automotive and other manufacturing industries because of their ability to meet wide ranging product functional requirements without compromising the performance of the product. They offer various advantages, including weight reduction, near net-shape processing capability, and their ability to be sintered to achieve desired properties in the end-product. However, in order to satisfy the product design requirements during manufacturing, they need to be machined to the required tolerances. Machining of powder metals is quite different to machining of traditional metals because of their specific properties, including porosity. This thesis work deals with the finish machining of powder metal steels in automotive applications, for increased tool-life/reduced tool-wear. Tool-life is affected by a variety of factors such as tool grade selection, tool coating, cutting conditions and tool geometry including cutting edge geometry. This work involves optimization of cutting conditions for plunge cutting and boring operations of automotive powder metal components using PCBN and carbide tools. The cycle time of the process introduces an additional constraint for the optimization model along with the tool-wear criterion. Optimized cutting conditions are achieved for maximum tool-life

Investigation of a novel manufacturing technique for two-dimensional machining of Polycrystalline Cubic Boron Nitride (PCBN) tools

The Laser/Water-Jet (LWJ) hybrid machining system, introduced and developed by the Iowa State University\u27s Laboratory for Lasers, MEMS, and Nanotechnology, was applied to overcome the major deficiencies associated with current EDM and laser machining techniques for shaping Polycrystalline Cubic Boron Nitride (PCBN) cutting tools from the blanks. For PCBN, the purpose of water in LWJ is twofold: phase transformation and thermal shock. Previously LWJ was used to perform straight line cuts on various materials including PCBN. In this work, a further investigation of an understanding of the action of water and two-dimensional contour cutting of PCBN was carried out. The role played by water in LWJ was compared with that of other fluids (argon, nitrogen, oxygen, and air) to illustrate the effectiveness of water in the controlled fracture mechanism of PCBN. In addition, a two-dimensional contour cutting of PCBN using LWJ was investigated by changing the crack direction to 60, 108, 120, 135 degrees and following a curve with 1 mm radius in accordance with the standard PCBN tool shapes. The phase transition and the cut quality were investigated using Raman spectroscopy, Scanning Electron Microscopy (SEM), and optical profilometer. Results indicated that water is the best medium to control the phase transition and apply the controlled fracture mechanism for PCBN. Also, it was shown that successful cuts were made with obtuse angles in contrast to acute angles. A preliminary qualitative model was presented to explain the observed experimental results