Stainless Steel

Weld cladding is a process for producing surfaces with good corrosion resistant properties by means of depositing/laying of stainless steels on low-carbon steel components with an objective of achieving maximum economy and enhanced life. The aim of the work presented here was to investigate the effect of auxiliary preheating of the solid filler wire in mechanized gas metal arc welding (GMAW) process (by using a specially designed torch to preheat the filler wire independently, before its emergence from the torch) on the quality of the as-welded single layer stainless steel overlays. External preheating of the filler wire resulted in greater contribution of arc energy by resistive heating due to which significant drop in the main welding current values and hence low dilution levels were observed. Metallurgical aspects of the as welded overlays such as chemistry, ferrite content, and modes of solidification were studied to evaluate their suitability for service and it was found that claddings obtained through the preheating arrangement, besides higher ferrite content, possessed higher content of chromium, nickel, and molybdenum and lower content of carbon as compared to conventional GMAW claddings, thereby giving overlays with superior mechanical and corrosion resistance properties. The findings of this study not only establish the technical superiority of the new process, but also, owing to its productivity-enhanced features, justify its use for low-cost surfacing applications.

Laser welding will be  an important welding process for different applications in aerospace , aircraft , automotive, electronics  and other industries, due to its capabilities like minimum heat affected zone, welding of various thicknesses, adoptability to welding of various materials possessing widely varying physical properties like melting point, absorption, reflectivity etc. It utilizes laser source as a non contact heat generation technology to weld different materials so as to achieve welds of high quality narrow width and high penetration depths without the need of filler wires. It may be necessary to understand the effect of process parameters on the weldability of materials for successful welding. Laser welding popularly uses two types of lasers like CO2 and Nd:YAG (neodymium doped yttrium – aluminium – garnet)  with different powers. Nd:YAG lasers are used to weld materials of different thicknesses involving powers upto 5 kW. Whereas, CO2 lasers are used for applications which involve higher powers upto 20 kW. Laser welding allows a direct transition from light energy into heat energy. This technique is involved with the process of laser - matter interaction in which various parameters such as pulse energy, pulse duration, spot size, welding speed, laser power, weld width, penetration depth, reflectivity, absorption coefficient, thermodynamic properties etc. are used for analysis. This paper presents a review of the different parameters including process as well as materials on the weldability of various materials like carbon steels, stainless steels, magnesium alloys, aluminium alloys, refractory materials such as vanadium, titanium, zirconium, tantalum etc. The selection of appropriate parameter for welding of specified material is discussed. The prominent weld defects common to the laser welding such as porosity, oxide inclusions, cracking, loss of alloying elements etc., are discussed as related to the microstructure as well as mechanical properties such as hardness, tensile strength and fatigue strength etc.

The creep properties of a nuclear-grade type 316 (L) stainless steel (SS) alloyed with nitrogen (316L (N) SS) and its weld metal were studied at 873 and 923 K in the range of applied stresses from 100 to 335 MPa. The results were compared with those obtained on ...

AISI 316 austenitic stainless steels have been plasma nitrided using a dc glow discharge unit in order to investigate the influence of gas composition on microstructure and corrosion behavior of treated samples. Corrosion properties of untreated and plasma nitrided 316 steels ...

This study describes the use of electrodeposited nanostructured hybrid nickel–cobalt hexacyanoferrate in electrochemical supercapacitors. Herein, various compositions of nickel and cobalt hexacyanoferrates (Ni/CoHCNFe) nanostructures are electrodeposited on an inexpensive stainless steel substrate using cyclic voltammetric (CV) method. The morphology of the electrodeposited nanostructures is studied using scanning electron microscopy, while their electrochemical characterizations are investigated using CV, galvanostatic charge and discharge and electrochemical impedance spectroscopy. The results show that the nanostructures of hybrid metal cyanoferrate, shows a much higher capacitance (765 F g−1) than those obtained with just nickel hexacyanoferrate (379 F g−1) or cobalt hexacyanoferrate (277 F g−1). Electrochemical impedance spectroscopy results confirm the favorable capacitive behavior of the electrodeposited materials. The columbic efficiency is approximately 95% based on the charge and discharge experiments. Long cycle-life and excellent stability of the nanostructured materials are also demonstrated during 1000 cycles.► Nanostructured hybrid nickel–cobalt hexacyanoferrate is used in supercapacitors. ► A high capacitance (765 F g−1) is obtained at a specific current of 0.2 A g−1. ► Long cycle-life and excellent stability are demonstrated during 1000 cycles.

The conductance and electrostriction of bilayer lipid membranes (sBLM) supported on stainless steel and on conducting polymer polypyrrole (PPY) were studied. We showed that an increase in ammonia concentration resulted in an increase in d.c. current flow across the PPY layer adjacent to the metal surface and that covered by the lipid bilayer. The elasticity modulus in the direction perpendicular to the sBLM surface (E) and the electrical capacitance (C) were characterized by a complicated dependence on the application of an external d.c. voltage. In the case of sBLM formed on the PPY layer and that modified by avidin-urease, higher values of E were observed and in addition the latter system was characterized by a less expressed hysteresis of E and C than the metal supported sBLM. This is evidence that sBLM formed on PPY layers is smoother and more homogeneous than that formed on a metal support. We developed a urea minisensor based on sBLM supported on a PPY layer. Avidin-biotin tec...

Direct Metal Laser Re-Melting is a variant of the Selective Laser Sintering process, a Rapid Prototyping (RP) technology. This tool-less manufacturing technology has the potential of producing complex, high quality components from single-phase metal powders in short time scales. This is made possible by the production of consecutive two-dimensional layers. Unfortunately, finished components manufactured by this technique have their integrity

The brake system is an important part of an automobile. It plays a vital role in helping the driver to reduce the speed of an automobile or to stop the automobile. Initially, when automobiles were first introduced, they were equipped with drum brakes. These drum brakes were cheap, easy to install and atmospheric agents cannot hinder their performance. Despite these advantages, the major disadvantage of the drum brake system is the poor heat dissipation. To tackle this problem, the automotive engineers came up with the disc brake system. The brake rotor is one of the most critical components of the disc brake system. The brake rotor is made up of a pure metal or a metal with certain reinforcements. These brake rotors are circular with perforations made in a particular manner to enable faster dissipation. These perforations help to reduce the weight of the disc brake rotor. The disc brake rotor is fixed to the wheel hub with brake calipers. In this review article, I will be critically analyzing various research articles on the thermal and mechanical properties of various brake rotor materials used in automobiles.

Most microbial electrolysis cells (MECs) contain only a single set of electrodes. In order to examine the scalability of a multiple-electrode design, we constructed a 2.5 L MEC containing 8 separate electrode pairs made of graphite fiber brush anodes pre-acclimated for current generation using acetate, and 304 stainless steel mesh cathodes (64 m2/m3). Under continuous flow conditions and a one day hydraulic