Stainless steel, especially, Austenitic stainless steel, because of their high corrosion resistance and customizable mechanical properties has become an indispensable part of the regularly evolving modern day technology. Stainless steels of various grades find applications in numerous fields starting from the household to the nuclear reactors; from food and beverage cans to construction of different automobile parts. The formation of impervious oxide layer on the surface makes it suitable for use in adverse environments such as sea water.
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...
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To obtain a detailed knowledge on the effect of Sensitization on the hardness of the samples, two kinds of hardness determination tests were performed.
(a) Micro Hardness
(b) Macro Hardness
(a) Micro Hardness
In order to perform the micro hardness test on the samples, they were first roughly polished using belt grinder. Then they were polished with the Emery papers as described in previous descriptions so as to obtain flat surfaces and to avoid anomalies in the results.
The micro hardness of the prepared samples were obtained by using a Vickers Micro hardness Tester (Model : Leco LV 700, USA). 5 readings were taken for each sample to calculate the average hardness. An indentation load of 5gf was used. After calculating the average hardness for each sample, mean variance and standard deviation (S.D.) was calculated to check the consistency of the data.
To start with, the first separation technique we performed on the heterogeneous mixture was filtration. According to our observations of the residue, we believed graphite was one of the substances in the mixture. Graphite, a known ingredient used in pencils, is black or dark grey in color, like the dark spots on the filter paper (Figure 1B), and has the ability to leave marks on paper and other objects. Of the potential components given to us, only graphite possessed the ability to make a mark on other surfaces. This was supported by the smudges left behind on our finger and filter paper (Figure 1A, bottom filter paper) when we touched the residue.
The surface morphology and the surface roughness of the untreated and treated PP samples were investigated by AFM. The Figure 1 represents the AFM images in a three dimensional view of untreated and treated samples in a time of 60s with various power rates. The scan size of all the images is 5×5 μm2. Evidently, the oxygen plasma treatment modified the surface morphology of the PP
Scanning electron microscopy (SEM) technique was employed extensively through want this study to examine and obtain images of prepared samples. The associated analytical facility of Energy dispersive X-Ray (EDX) analysis was used to identify and quantify the elemental composition of the prepare samples.
Nine times out of ten, the idea of getting braces would instantly be met with resistance and dread by anyone, but more so by teens and young adults. It seems that wearing braces is always followed by the stigma of pain, discomfort, and being labelled as "geeky". But despite the slight pain and discomfort, braces get an important job done--that of straightening crooked, misaligned teeth, or correcting one's bite. See, it's not really as bad as you think it is because braces have a purpose. Fortunately, there is now the Invisalign treatment. It's a more pleasant alternative to wearing traditional metal braces--invisible braces.
The stainless steel columns seem to have been made by casting and then polished to achieve their current look. Casting is an artistic manufacturing process by which hot liquid materials are poured into a mould and allowed to sit until cooled and solidified. Then the Mould is taken off of the art piece or broken off the art in some cases. This method is used because of the difficulty that would arise from having to figure out how to manipulate materials such as steel or aluminum that are very hard to work
The next test, Microcrystalline, that will be performed is the microcrystalline test to confirm the color test findings. The Microcrystalline test requires the Forensic Chemist to drop a chemical reagent onto the powder that is being questioned at this time on a microscope slide. When a little amount of time has passed the chemist will look through a microscope to observe the regents chemical reaction. This chemical reaction will produce a “crystalline precipitate” (Saferstein, 2013). The shape and size of the crystals are highly likely to give the characteristics of the drug when observed through a microscope (Saferstein, 2013).
Hardness test In this study hardness was determined using standard Rockwell A. The tests were conducted at room temperature and under ambient humidity conditions. Hardness testing machine (Avery Denison 6407 150Kgf) was used in the test.
Do you go out hunting a lot? Are you in need of a high-quality, reliable knife? Do you need something that can just as easily dress an animal as it can whittle through wood? If you’re looking for a durable, rugged, and dependable hunting knife, then look no further than the Kershaw Diskin 1085. When it comes to hunting knives and equipment, one of the best companies to buy from is Kershaw. For over forty years, the brand has become synonymous with top-rated hunting gear and nowhere is that more evident than in Kershaw knives. The Diskin 1085 is the perfect example of the company’s commitment to quality, and today I’ll show you why this knife is an indispensable asset to any hunter out in the field.
Stainless steel is one of the materials used in this kettle and is now used more frequently within kettles today because is it impressive properties, one of the main being its resistance ...
Structural rust is when the corroded medal has developed pitting, or in some cases, outright holes in the metal. In these cases, the structural qualities of the metal are compromised. Since repairing the rust is impossible without replacing the entire part in cases of structural rust, you'll want to avoid vehicles in this condition. Location, Location,
Stainless steel is a type of alloy that has a very strong lattice structure (an arrangement/ shape of the crystals or other objects) which in some case can be more beneficial than others depending on the type of application it may be used for. In many cases this structure will make the material more suited to being used in engineering applications such as tools for instance a hammer (stainless steel alloys) , also they can be used for gears, engines, electrical motors and hydraulic systems because the structure makes the material so strong. So when the arrangement of the structure is as above it makes the overall material even stronger which makes it a good for all the applications stated above. I believe its strength and durability are its main properties as these are commonly needed in the engineering industry, although it is also very well known to be used for its corrosion resistance as it is resistant to many types of corrosion. It is used for these properties because the components such as gears need to be strong in order to keep transferring and altering the rotary motion and torque exhibited in the machine that it may be used in, durable to withstand any loads or pressure put onto it and also corrosion resistance to give the components a bigger life span and increase its rate of work throughout its required use.
The basis for the understanding of the heat treatment of steels is the Fe-C phase diagram. Because it is well explained in earlier volumes of Metals Handbook and in many elementary textbooks, the stable iron-graphite diagram and the metastable Fe-Fe3 C diagram. The stable condition usually takes a very long time to develop, especially in the low-temperature and low-carbon range, and therefore the metastable diagram is of more interest. The Fe-C diagram shows which phases are to be expected at equilibrium for different combinations of carbon concentration and temperature. We distinguish at the low-carbon and ferrite, which can at most dissolve 0.028 wt% C at 727 oC and austenite which can dissolve 2.11 wt% C at 1148 oC. At the carbon-rich side we find cementite. Of less interest, except for highly alloyed steels, is the d-ferrite existing at the highest temperatures. Between the single-phase fields are found regions with mixtures of two phases, such as ferrite + cementite, austenite + cementite, and ferrite + austenite. At the highest temperatures, the liquid phase field can be found and below this are the two phase fields liquid + austenite, liquid + cementite, and liquid + d-ferrite. In heat treating of steels the liquid phase is always avoided. Some important boundaries at single-phase fields have been given special names. These include: the carbon content at which the minimum austenite temperature is attained is called the eutectoid carbon content. The ferrite-cementite phase mixture of this composition formed during cooling has a characteristic appearance and is called pearlite and can be treated as a microstructural entity or microconstituent. It is an aggregate of alternating ferrite and cementite particles dispersed with a ferrite matrix after extended holding close to A1. The Fe-C diagram is of experimental origin. The knowledge of the thermodynamic principles and modern thermodynamic data now permits very accurate calculations of this diagram.
7. Aziz RD, Gonzalez NAG, Kasim NHA. Microleakage Testing. Annals of Dentistry 1997; 4(1): 31-37.
Gold is one of the most popular metals as investment. Because of its high and consistent value, it is considered one of the safest commodities to invest in. There are several ways of using gold as an investment. Gold can be physically bough in the form of bullion bars or bullion coins. Gold exchange products can be traded in major stock exchanges in the same manner as shares. These include closed-end products or CEFs, exchange-traded notes or ETNs, and exchange-traded funds or ETFs. Gold accounts can be availed from banks and their management greatly depends on whether it is an unallocated or an allocated gold account. Gold certificates used to circulate as money until the United States restricted private gold ownership in 1933. Buying shares in gold mining companies comes with structural, management, and political risks but investing in the right company at the right time can increase share prices to as much as 20%.