Age hardening heat treatment behavior of as-cast Mg–Zn–Al alloys

Magnesium alloys have generated renewed interest as a light alloys; replacing some conventional structural materials for weight reduction in applications like aerospace, automotive and electronics industries. In interior components and powertrains, cast alloys are widely used and represent more than 99% of magnesium alloys used today, whereas only a few wrought products are used. Mostly in automotive applications, Mg-engine block can noticeably reduce the weight and consequently its fuel consumption and environmental impact. Due to solid-state precipitates, these alloys are strong in nature and are produced by an age-hardening heat treatment process. In the present work the age hardening behavior of the as cast Mg–Zn–Al alloys (ZA85 alloy) in the composition of 8 wt. %Zn, 5 wt. %Al has been investigated. Through the differential thermal analysis (DTA) studies, it has been found out that dissolution temperature of ternary eutectic precipitates is present in the alloy. Based on the DTA results, the as cast samples have been solutionised at 360 °C temperature for different intervals of time. Solutionising time has been optimized from the enthalpy values of un-dissolved precipitates. The solution treated samples have been then aged at temperature of 180° C for different time intervals. From the peak hardness values, the ageing conditions have been optimized

The effect of surface texturing in the sliding surface on tribological characteristics of alloy steel under wet condition

Surface texturing plays a significant role on the tribological performance of contact surfaces. The tribological characteristics are mostly dependent upon the different pattern and methods of surface texturing. This research works investigates lubricated wear behaviour on circular dimples textured EN-31 alloy steel materials using DUCOM linear reciprocating tribometer. The surface dimples are fabricated by micro-EDM and micro-drilling CNC methods. Initially plane surfaces are tested under different lubricants ISO-68 and ISO-220 oil on a couple of EN31 plates with EN8 steel pin. At loading conditions the results clearly shows that the ISO 68 oil gives better performance than ISO-220 oil in terms of frictional force and COF. The operation during test under ISO-220 oil observed is very noisy and wear rate is also more. Then after experiments under different load conditions on textured surfaces were investigated using optimized ISO-68 oil. An experimental results on m-EDM provides superior frictional characteristics with respect to m-CNC. Surface texturing may act as wear debris trapper, lubricant reservoirs, hydrodynamic lift, and retarding the lubricant molecules flow in a particular path where potential exists. Here micro-dimples EDM surface textures can enhance mixed lubrication and in mixed lubrication the friction is least and this may leads to decrement of wear loss

Experimental investigation of hardness of FSW and TIG joints of Aluminium alloys of AA7075 and AA6061

This paper reports hardness testing conducted on welded butt joints by FSW and TIG welding process on similar and dissimilar aluminium alloys. FSW joints were produced for similar alloys of AA7075T651 and dissimilar alloys of AA7075T651- AA6061T6. The Friction stir welds of AA7075 & AA6061 aluminium alloy were produced at different tool rotational speeds of 650,700, 800, 900, 1000 and transverse speed of 30, 35, 40 mm/min. TIG welding was conducted along the rolling direction of similar and dissimilar aluminium plates. The Brinell hardness testing techniques were employed to conduct the tests; these tests were conducted on the welds to ascertain the joint integrity before characterization to have an idea of the quality of the weld

Al2O3 and TiO2 flux enabling activated tungsten inert gas welding of 304 austenitic stainless steel plates

Gas tungsten arc welding (GTAW) is important in those manufacturing where it is significant to control the mechanical and metallurgical characteristics and its weld bead geometry. This work has been committed to study the influence of oxide fluxes on welding of 4 mm thick 304 austenitic stainless steel plates. The Al2O3 and TiO2 were used as an oxide flux in powder form and are mixed with the acetone. The prepared mixture is applied on bead plate without any joint preparation and without filler wire addition. The Taguchi method with L9 orthogonal array is used to determine the optimal parameters. The current work aims to explore the influence of weld parameters on weld bead geometry (i.e. weld bead width, penetration and angular distortion), and mechanical & metallurgical characteristics for 304 stainless steel welds. The oxide flux seems to narrow the arc and thereby the current density increases at the anode spot, that results in high weld depth

Characterizations of TIG welded joints of Unalloyed Commercially Pure Titanium Gr-2 for Weld Process Parameters

Titanium and Titanium Alloys can be welded by gas tungsten arc, gas metal arc, plasma arc and electron beam welding processes. Titanium material is a reactive metal and is sensitive to embrittlement by oxygen, nitrogen, and hydrogen gas, at elevated temperatures. Consequently, the metal must be protected from atmospheric contamination. This can be provided by shielding the metal with welding grade inert gas. The present work describes the application of TIG arc welding to titanium and  investigated the effect of welding parameters like weld current, weld gap and gas flow rate on mechanical properties of welded joints of unalloyed commercially pure titanium Gr-2 materials. Taguchi optimization method has been used to find out optimal setting of parameters for weld joints characterization. The welded joints showed an ultimate tensile strength of about 429 MPa with 23.33% elongation. A significant grain coarsening is noticed in the fusion zone consisting of α-phase in different direction bounded by β-phase. The hardness value at fusion zone and base metal are typically observed to be 235 and 145HV

Reinventing Gandhian ideas and practice of consensual democracy, satyagraha, and village socialism in today’s context : the case of village Mendha Lekha, India = 重建甘地的共識民主、宗教信仰和鄉村社會主義的思想和實踐 : 以印度門達列哈村 (Village Mendha Lekha) 為例

On 8 July 2020, there were three sessions of a workshop on “Confronting the Triple Trap The Pandemic, Economic Downturn, and Climate Crisis in India and China” (直面三重困境 : 新冠疫情、經濟衰退與氣候危機). This session focuses on the voices of villages and rural area in India. It is moderated by SIT Tsui Jade Margaret (Southwest University, China) and there are three speakers to deliver presentations : Pallavi VARMA PATIL (Living Utopias; Azim Premji University, India) Sujit SINHA (Living Utopias; Azim Premji University, India) Mohan Hirabai HIRALAL (Vrikshamitra, Maharashtra, India

Comparative study between Buprenorphine and Fentanyl transdermal patch to evaluate post-operative pain relief after cardiac surgery: A randomized control trial study

Introduction: Pain due to thoracotomy creates greatest demand for postoperative analgesia. Multimodal analgesia with various routes can be of great help to fulfill demands of analgesia in these patients. Opioids given by transdermal route offers newer modality of management with potential benefits of being noninvasive, sustained blood levels and bypasses first pass metabolism. We aimed to evaluate efficacy of Buprenorphine and Fentanyl Transdermal patch for post-operative pain relief after cardiac surgery. Methods: It was prospective, randomized, double-blind study in which 60 adult patients undergoing cardiac surgery were randomly segregated into two groups. Group A: 30 patients received Buprenorphine transdermal patch (10mcg/hr) and Group B: 30 patients received Fentanyl transdermal patch (50mcg/hr) 12- 24 hours prior to extubation. Analgesia was assessed using VAS score along with hemodynamic parameters and adverse effects. Results: Demographic parameters, baseline hemodynamics and perioperative hemodynamics were comparable. Baseline VAS score was comparable in two groups however statistically significant difference in two groups in VAS was observed thereafter till 72 hours. VAS score was higher in group A as compared to group B at the time of removal of ICD. 3 (10%) and 2 (6.7%) patients in Group A and Group B respectively required rescue analgesic which was not significant. Time for requirement of first rescue analgesic was significantly longer in Group B compared to Group A ie767.13 ± 73.59 minutes vs. 1224.37 ± 39.37 minutes. Adverse effects were comparable in two groups. Conclusion: Fentanyl and Buprenorphine TDDS are effective in postoperative analgesia in cardiac surgical patients. However Fentanyl TDDS has better analgesia

Comparative study between Buprenorphine and Fentanyl transdermal patch to evaluate post-operative pain relief after cardiac surgery: A randomized control trial study

Introduction: Pain due to thoracotomy creates greatest demand for postoperative analgesia. Multimodal analgesia with various routes can be of great help to fulfill demands of analgesia in these patients. Opioids given by transdermal route offers newer modality of management with potential benefits of being noninvasive, sustained blood levels and bypasses first pass metabolism. We aimed to evaluate efficacy of Buprenorphine and Fentanyl Transdermal patch for post-operative pain relief after cardiac surgery. Methods: It was prospective, randomized, double-blind study in which 60 adult patients undergoing cardiac surgery were randomly segregated into two groups. Group A: 30 patients received Buprenorphine transdermal patch (10mcg/hr) and Group B: 30 patients received Fentanyl transdermal patch (50mcg/hr) 12- 24 hours prior to extubation. Analgesia was assessed using VAS score along with hemodynamic parameters and adverse effects. Results: Demographic parameters, baseline hemodynamics and perioperative hemodynamics were comparable. Baseline VAS score was comparable in two groups however statistically significant difference in two groups in VAS was observed thereafter till 72 hours. VAS score was higher in group A as compared to group B at the time of removal of ICD. 3 (10%) and 2 (6.7%) patients in Group A and Group B respectively required rescue analgesic which was not significant. Time for requirement of first rescue analgesic was significantly longer in Group B compared to Group A ie767.13 ± 73.59 minutes vs. 1224.37 ± 39.37 minutes. Adverse effects were comparable in two groups. Conclusion: Fentanyl and Buprenorphine TDDS are effective in postoperative analgesia in cardiac surgical patients. However Fentanyl TDDS has better analgesia