a. Introduction
In the quality assurance of machine components the so-called finishing and super-finishing processes have important roles. During recent years, the post-machining cold forming methods such as burnishing, shot peening, etc., have occupied a very important place in industry, because they are reported to induce compressive residual stresses on the work piece surface, which in turn, results in improvement of tribological properties such as wear resistance, fatigue life, corrosion resistance, etc. Burnishing, which is one of the effective methods used to improve the surface properties, is essentially a cold working process involving movement of raised micro-irregularities on the surface layer accompanied by filling up of micro-cavities.
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[13] reports an experimental investigation on vibratory ball burnishing process. Experiments were carried out to study the influence of various process parameters such as burnishing speed, feed, ball force, frequency and amplitude of vibration on the surface finish and micro hardness of surface layers produced by vibratory burnishing process. Experiments were planned based on response surface methodology (RSM) technique. Two mathematical models correlating process parameters with response parameters such as surface roughness and micro hardness were obtained. Influence on surface roughness can be explained as ahead; From results it is seen that increase of burnishing speed deteriorates the surface finish. Generally surface roughness increases with the feed and there is an interaction between ball force and the feed. Combination of low feed (0.07 mm/rev) with large force deteriorates the surface finish possibly due to over hardening and flaking of surface layers. Concerning the effect of burnishing force, for a constant feed value, increase of ball force initially improves the surface finish and then causes deteriorate, there by suggesting an optimum ball force. Considering the effect of frequency of vibrations it can say that very good surface finish can be obtained with the combination of large frequency and high ball force. In the range of parameters studied, the optimum ball force lies between 15-25 kgf. Influence on micro hardness explained here; it is …show more content…
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The high temperature application of Austenitic Stainless Steel is somewhat limited because at higher temperatures it undergoes a phenomenon called Sensitization. According to Ghosh et al. [1], it refers to the precipitation of carbides and nitrides at the grain boundaries. Precipitation of Chromium rich carbides (Cr23C6) and nitrides at the grain boundaries result when the Austenitic stainless steel is heated and held in the temperature range of 500-8500C (773K-1123K). This precipitation of carbides taking place at the grain boundary is because of their insolubility at these temperature ranges. This leads to Chromium depreciated regions around the grain boundaries. So the change in microstructure is takes place and the regions with low Chromium contents become susceptible to Intergranular Corrosion (IGC) and Intergranular Stress Corrosion Cracking (Alvarez et al.) [1, 2]. Along with carbides and nitrides there is formation of chi phase. The chi phase, which is a stable intermetallic compound, consists of Fe, Cr, and Mo of type M18C. Some studies reveal that sensitization may lead to formation of Martensite. In addition to the altered microstructure, mechanical properties of the Austenitic Stain...
-can be built up in thing translucent layers like a varnish to make areas of glowing color or worked into fine details
Friction stir welding is a solid state welding process; this remarkable up-gradation of friction welding was invented in 1991 in The Welding Institute [1]. Figure 1 shows the schematic representation of the Friction Stir Welding process. The process starts with clamping the plates to be welded to a backing plate, so that the plates do not fly away during the welding process. A rotating wear resistant tool is plunged on the interface between the plates to a predetermined depth and moved forward in the interface between the plates to form the weld. The external tool has a probe and shoulder which stirs the material to be joined and forges the surface. FSW comes together with forging and extrusion processes. The probe and shoulder extrudes the material by stirring and the shoulder alone forges the material surface to be joined.
For best performance in flame retardancy without deteriorating the mechanical properties (tensile strength), the optimum ratio of APP/MEL was found to be 3:1 with loading of 30%. Besides this the incorporation APP and/or APP and MEL into composites promoted the char formation and correspondingly improved the thermal stability [79].
[14] Liu, J. (2013). "Effect of diffusion annealing on interface microstructure of hot rolled high boron alloyed stainless steel composite plate". Transactions of Materials and Heat Treatment (1009-6264), 34 (4), p. 90.
Metal finishing is the critical part and step in preparing the metal for painting. It happens between the bumping stage when the metal is pried, hammered, pulled, and pushed into shape and the filling stage, when the small defects and details in metal finished surfaces are filled before being painted. Any type of finish is applied over your work weather the it be solvent, powder coated, or plastic it will have an index of reflection and ...
2. What is the difference between a.. Material of the ball; as the ball is the same one used, this will.
Milling offers the advantages of being highly precise and having much smoother surface finish (surface roughness of easily around 1 µm ) compared to powder bed fusion additive manufacturing (layer thickness in the range of 20 µm and above; surface roughness of 15 µm and above ). Flat surfaces and sharp corners can be obtained with CNC milling. Similarly, features such as threads and holes are more accurately created through
...roved hardness, strength and wear resistance are achieved [12, 13]. The coated material (CSZ) can be applied as thermal barriers, having high temperature resistance. These coatings permit higher operating temperatures by controlling the thermal subjection of structural components. There as increase in part life by controlling oxidation and thermal fatigue [14]. The thermal resistance characteristics of the surface coating basically depend on the following parameters. Distance between spray nozzle and substrate, flow rate of the precursor solution, post heat treatment temperature and duration of heat treatment [15-17]. The required thermal energy varies for different materials and solvents used in the spray process. The atomization of the spray solution, into a spray of fine droplets also depends on the geometry of the spraying nozzle and pressure of a carrier gas
From the computations above, it is clearly illustrated that there is a disparity between the loading of the boards into the machines and the output of the cleaning and the coati...
Four brass wedges were tested. Two were cold rolled to a thickness of 5.0 mm and two were cold rolled to a thickness of 2.5 mm. One wedge of each thickness was then annealed for 1 hour at 350 °C. Because the wedges varied in thickness across the length, multiple cold work values were able to be recorded. Hardness and thickness measurements were taken before and after the cold rolling and after the annealing as shown in Figure 1. Generally, as cold work increased, hardness increased.
A wide variety of coating alloys and wrought alloys can be prepared that give the metal greater strength, castability, or resistance to corrosion or high temperatures. Some new alloys can be used as armor plate for tanks, personnel carriers, and other military vehicles.
If work-hardening is performed at elevated temps it is said to be hot-worked. In contrast cold-working is done right around room temperature. In both situations the work hardening increases the strength and hardness because of plastic deformation. This causes atoms in a crystal to become disordered, which means that the atoms have moved into a disordered structure. This then raises the strength and hardness by impairing the easy movement of dislocations. Cold working was done at first along with harness testing, once familiarized with all of this testing relationships between hardness, microstructure, and degree of work hardening of brass were
Multiple finishing techniques – die cast parts can be produced with smooth or textured surfaces and they are easily plated or finished with a minimum of surface preparation.
Metals possess many unique fundamental properties that make them an ideal material for use in a diverse range of applications. Many common place things know today are made from metals; bridges, utensils, vehicles of all modes of transport, contain some form of metal or metallic compound. Properties such as high tensile strength, high fracture toughness, malleability and availability are just some of the many advantages associated with metals. Metals, accompanied by their many compounds and alloys, similar properties, high and low corrosion levels, and affects, whether negative or positive, are a grand force to be reckoned with.