Review on Weldability Prospects of Super Austenitic Stainless Steels

Super Austenitic Stainless Steels (SASS) belongs to the category of austenitic stainless steels which were known for their excellent corrosion resistance when used in structural applications like desalination plants, oil piping systems, heat exchanger equipments which demands high temperature service and harsh environments. Several works on SASS dealt about the corrosion resistance of the material in its normal base metal form. But structural uses needs SASS to be welded with similar or dissimilar materials to fit into the applications. This study aims to present a detailed view on issues related to the weldability of super austenitic stainless steels and the future scope of welding on SASS.

DEVELOPMENT COMPOSITE ALUMINIUM/FLY ASH WITH POWDER METALLURGY METHOD USE EGG YOLK AS SPACE HOLDER

Metal matrix composite has been used widely in some applications such as the automotive and aerospace industries. In this work, Aluminum/Fly ash composite material was made with an egg yolk space holder and the manufacturing process was successfully carried out. The process includes the mixing, stirring, drying, and sintering processes that were undertaken including the powder metallurgy method. The metal form has successfully been fabricated however the hardness test results for specimens were not very satisfactory. The Aluminum/Fly ash porous composite materials with egg yolk space holders were was characterized using X-Ray Florence (XRF), X-Ray Diffraction (XRD) test by producing the main peak of Al N and Al2O3. Observation of SEM by showing phenomena such as; cracks, alignment, and porous. Density Testing by producing an average porosity of 28.87%. The observation of Optical Microscopes by showing the shape of the shaft that is not homogeneous.

The Behaviour of Fresh Concrete with Varying Coarse Aggregate Content at the Concrete-Steel Wall Interface

The interaction between concrete and steel occurs during concrete mixing and finishing processes, during filling of concrete moulds, formwork, composite columns and during pumping of concrete mixtures. More experimental investigation is required to predict variations in interface friction, as a result of the composition of the lubrication layer which depends on the composition of concrete. This study provides experimental results to allow for a better understanding of friction at concrete-steel interface, with changes in the coarse aggregate (CA) content in the aggregate mixture (AM). Friction tests on fresh concrete have been carried out using the BTRHEOM tribometer (Nantes, France) and the interface parameters were calculated on the basis of the interface friction between the concrete and the steel wall, through the ADRHEO software. The roughness parameters were measured along the length of the rotary steel cylinder of the tribometer. In addition, the roughness of new and modified metal form-lining in steel composite columns was also measured. Variations in the CA content in the AM in the 42 to 52% range had minimal effects on the yield stress of the interface. The viscous constant of the interface as measured with a tribometer decreased, when the roughness parameter Rt values of the rotary cylinder wall, which refer to the absolute vertical distance between the maximum profile peak height and the maximum profile valley depth along the sampling length, were in the 17.10 to 28.73 μm range. The roughness profile peaks’ asperity recorded, was higher for the worn metal form-lining and for the steel composite columns with the inner surface covered in rust, when compared to the rotary cylinder roughness profile. The hypothesis is based on the principle that a sufficient lubrication layer, with the required thickness of fine mortar is created at the interface between the concrete and the metal form-lining or steel composite column wall, when the CA content in the AM varies in the range from 42 to 52% and the wall roughness parameters (Rt) of these elements varies in the 15.00 to 30.00 μm range.

Hydrometallurgical Process and Economic Evaluation for Recovery of Zinc and Manganese from Spent Alkaline Batteries

An innovative, efficient, and economically viable process for the recycling of spent alkaline batteries is presented herein. The developed process allows for the selective recovery of Zn and Mn metals present in alkaline batteries. The hydrometallurgical process consists of a physical pre-treatment step for separating out the metal powder containing Zn and Mn, followed by a chemical treatment step for the recovery of these metals. Sulfuric acid was used for the first leaching process to dissolve Zn(II) and Mn(II) into the leachate. After purification, Mn was recovered in the form of MnO2, and Zn in its metal form. Furthermore, during the second sulfuric acid leaching, Na2S2O5 was added for the conversion of Mn(IV) to Mn(II) (soluble in the leachate), allowing Mn to be recovered as MnCO3. Masses of 162 kg of Zn metal and 215 kg of Mn (both in the form of MnO2 and MnCO3) were recovered from one ton of spent alkaline batteries. The direct operating costs (chemicals, labor operation, utilities, energy) and indirect costs (amortization, interest payment) required for a plant treating 8 tons of spent batteries per day was calculated to be $CAD 726 and $CAD 534 per ton, respectively, while the total revenue from the sale of the metals was calculated at $CAD 1359.6 per ton of spent batteries. The development of this type of cost-effective industrial process is necessary for a circular economy, as it contributes to addressing environment- and energy-related issues, and creates opportunities for the economic utilization of metals.

PENGEMBANGAN METODE ELEKTRODEPOSISI UNTUK PENGAMBILAN KEMBALI PERAK DARI LIMBAH FOTORONTGEN

Silver in its ionic form is one of the heavy metals dangerous if it is discharged into the environment or into the body of humans or other living things. Silver metal pollution sources, one of which comes from waste fixer which is a waste from the photorontgen process. However, silver in its metal form has a high economic value. Therefore, the development of techniques or methods of recovering silver from the waste solution and turning it into a metal form is important to do so that the metal does not pollute the environment and can be reused economically. One method that can be done is by electrolytic deposition or electrodeposition in which silver in the form of a silver thiosulfate complex compound in the photorontgen waste is converted to Ag metal through a redox reaction. To obtain good quality and quantity of silver deposits in the electrodeposition process, it is necessary to optimize several factors that influence, among others, optimization of potential difference, time and pH of the solution. This study aims to determine the effect of potential difference, time and pH of the solution on the efficiency of the electrodeposition process. Electrodeposition efficiency was determined based on the percentage of reduced silver mass calculated from the decrease in Ag concentration in photorontgen waste solution before and after the electrodeposition process. Based on the results of the study obtained the optimum electrodeposition process at a potential difference of 8 V for 75 minutes and the pH of the waste is 3, where the mass percent of silver which is reduced from waste is 86.49%.

KARAKTERISASI HASIL PENGELASAN GTAW PADA BAJA KARBON RENDAH DENGAN VARIASI SUDUT GEOMETRI ELEKTRODE DAN BESAR ARUS PENGELASAN

In the application of welding "GTAW" has several advantages such as welding results do not need to be cleaned from slag or corrosion residue. Due to the above-mentioned advantages, the precise determination of weld parameters and offset by the welding skills of welded characteristics will be affected. The purpose of this research is to know the characteristic of GTAW welding on low carbon steel, by observing the shape of weld bead and supported by the result of macro photo of welding result from various variations of currents and variations of the angle geometry of tungsten electrode. The method used in this study is an experimental method, with treatment of parameters of parameters of current and parameters of angle geometry variation of tapering of tunsten electrode. Analyze method is done to welding result and macro photo of T connection weld result. From the analysis of GTAW weld metal form with type T connection through variation of electrode geometry angle and strong welding current in this research, can be drawn some conclusions, among others, from some variation of weld geometry angle which gives good shape of welding characteristic and deep penetration is angle 300 of ampere 90 A.

Od undergroundu do mainstreamu – rozwój polskiego black metalu w XXI wieku

From underground to mainstream – evolution of Polish black metal in the 21st century Black metal in the 21st century, especially In Poland is resurrecting. The 1990’s was a rough time for this musical genre due to its rebellious nature. Modern black metal, highly developed by polish bands, is highly different than its generic predecessor. What is observed is an innovative direction to black metal form and content which structures an avant-garde genre, aspiring to enter the popular culture.

Thermal Hardening of the Tin Bronze Alloyed with Nickel

The article represents the results of thermal hardening of the stannic bronze alloyed with nickel without quenching. The samples were obtained by molding into a metal form applying centrifugal way of molding. Metallographic and phase analyses were carried out to define the mechanism of thermal hardening. The aging mode was chosen to ensure the maximum hardness of stannic bronze with nickel additives of the chosen structure.