Figure 7: Effect of tempering temperature on hardness of D2 tool steel at 970, 980,990, and 1000oC austenitizing temperatures.
At tempering temperature range of 200oC- 250oC, for the rise of 25% (50oC) of tempering temperature, the hardness decreases from 69Rc to 67Rc (2.89%). At tempering temperature range of 250oC- 300oC, for rise of 20% (50oC) of tempering temperature, the hardness decreases from 67Rc to 65Rc (2.98%). Thus the rate of decrease in hardness varies between nominal value of 2.81% to 2.98%.
2.1.7 S. Prabhu, B. K. Vinayagam studied Modeling the machining parameters of AISI D2 tool steel material with multi wall carbon nano tube in electrical discharge machining process using response surface methodology-dec-2011 This work investigates the machining characteristics of American Iron and Steel Institute (AISI)
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WEAR TESTING OF D2 TOOL STEEL UNDER HARDENING, SINGLE TEMPERING (HT)
3.1 HARDENING
The first step in the heat treatment of AISI D2 tool steel was hardening. The purpose of hardening was to harden steel to increase the wear resistance, cutting ability. Hardening of AISI D2 tool steel was done at a temperature of 1020°C [6] for 1 Hour. Harden AISI D2 tool steel followed air cooling which provides great benefit of minimizing distortion and dimensional changes [6]
3.2 TEMPERING
The process which consists of heating the hardened components to a temperature between 100°C and 700°C, holding at this temperature for specific period and cooling to room temperature, usually by air is called as „tempering‟.
Purpose of tempering is as follows
1. To relieve the internal stresses developed due to rapid cooling of steels after hardening process and due to volume changes occurring in the austenite to martensite transformation, to reduce brittleness,
2. To reduce hardness and to increase ductility and toughness,
3. To eliminate retained austenite [7].
Table No-1 working condition of HT
Sr. No. Normal Load FN (Kg, N) Velocity V
1. Decide on a range of temperatures from 5 °C to 35 °C to be tested.
It provides effective and low cost lubrication of stern tube bearings. It is highly recommended in Cedevall type of stern tube bearings where high viscocity and readily emulsifying oil is of high importance. It is also used in fin tilting bearings as well as the crux trunnion bearings.
]. Some alloying elements sometimes added to impart special characteristics to brass. Lead, which is insoluble in copper alloys, used to improve machinability of leaded brass. However, Pb and Bi or other elements that are used to improve the machinability often deteriorate the low and high temperature ductility of brass [11]. The content of Pb element is varies between 2.5 and 3.5 %, which make the machining processes at high speed and good surface [12]. The solubility of lead in copper alloys is very low therefore, it is found in microstructure as dispersed globules all over the material. These globules lead act as a lubricant decreasing the friction coefficient between the tools and the materials by creating discontinuities of chip fragmentation. Therefore, it makes reducing in cutting force and then, the tools wear rate is minimized [13]. Different alloying elements help to improving the machinability are usually added to brass. The most common element using in this situation is lead, which improving the machinability with
Studies on the oxidation of stainless in hot rolling have obtained much attention during the last few decades where the finishing temperature ranges from 850-1100 °C.
-Developed and implemented strip casting overseas to eliminate a step in the steel making process
It is thus a thermal erosion process. The sparks are created in a dielectric liquid, generally water or oil, between the work piece and an electrode, which can be considered as the cutting tool. There is no mechanical contact between the electrodes during the whole process. Since erosion produced by electrical discharges, both electrode and work piece have to be electrically conductive. Thus, the machining process consists in successively removing small volumes of work piece material, molten or vaporized during a discharge. The volume removed by a single spark is small, in the range of 10-6-10-4 mm3 but this basic process is repeated typically 10,000 times per
The main objective of this project was to investigate the influence of blade and clearance on the work material and the parameters affecting resistance spot welding such as heat transfer from the electrodes to the sheet-sheet interface, current requirement to achieve the necessary heat to form weld nugget and influence of clamping force on sheet welding.
Xie, J. "Weld Morphology and Thermal Modeling in Dual-beam Laser Welding." Was.org. American Welding Society, n.d. Web. 24 Mar. 2014. .
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...
I. Martensitic stainless steels have good mechanical strength and are moderately corrosion resistant. Because of their excellent corrosion resistance and mechanical strength, martensitic stainless steels are used for manufacturing the steam turbine blades, heat exchangers, automotive components and structures, petrochemical & process piping. Properties of martensitic stainless steel can be changed by the heat treatment. Increasing productivity of any welding process while maintaining or even improving the weld quality has been the task of researchers in the field of development of welding processes. Over the years, welding methods and techniques have developed to great extent [3].
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.
Some steel containers are made through deforming the steel by means of extruding, forging, spin forming, ...
"Metal Melting 101 - How To." Motorcycle Cruiser. Shop Talk, 24 May 2009. Web. 28 Apr. 2014.
Heat Treatment is that the controlled heating and cooling of metals to change their physical and mechanical properties whereas not changing the merchandise kind.Heat treatment is usually done unknowinglyas aresults of manufacturing processes that either heat or cool the metal like attachment and forming. Heats Treatment is sometimes associated with increasing the strength of cloth but it can also be accustomedalterbound manufacture ability objectives like improve machining, improve formability, and restore plasticity when acold operative operation. so it is a awfully sanctioning manufacturing methodology that will notsolelfacilitate completelydifferent completely manufacturing methodology but can also improve product performance by increasing strength or different fascinating characteristics. the heattreatment operation ar oftenoutlined
Annealing and tempering are not the same types of heat treatment. Annealing can be defined as heating the steel to aus...