Thermomechanical Treatment Influence on the High-speed Steel Hardness and Wear
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1. Introduction
In general, most pieces executed for the industry are of the metallic materials, being processed by cutting; therefore the consumption of cutting tools is significant. Although the materials for cutting-tool manufacturing are more and more diversified, their range being in a permanent extension, the old materials have not been utterly abandoned, but their role has only diminished. Nowadays, the tools obtained by physical vapour-deposit methods (PVD) represent more than 50% of the overall cutting tool consumption and are likely to go beyond. Thanks to an acceptable price/quality ratio and to good toughness
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High temperature thermomechanical treatment (HTTMT) can be used for processing tools and other high-speed steel components of simple geometrical shapes - Dobrzanski[4]. Applying thermomechanical treatments, the resistance properties increase simultaneously maintaining the good values of plasticity, when the deformation degree is between 40-50% - Popescu[5]. If deformation occurs through forging, the resilience has maximal values for a deformation degree of 60-80%. In the case of other high-speed steels, improved characteristics of the hardness, moment-resistance and resilience were obtained, for deformation degrees of 45-85% - …show more content…
Microstructure of plastic deformed HS2-9-1-8 steel: = 0% (a), = 50% (b), = 70% (c)
The thermomechanical treatment continued with an oil quenching (oil temperature 100oC), which maintained the positive evolution of the microstructure (Murakami attack reagent, 400 x enlargement). For =70% one observed the carbides with small dimensions (dark colour area) and their uniform distribution. The =70% microstructure is better than =60% and obviously better than =0% (see figure 2). Figure 2.Microstructure of the thermomechanical treatment HS2-9-1-8 steel: = 60% (a), = 70% (b)
3. Experimental Results
The tests were performed on cylindrical samples of HS2-9-1-8 high-speed steel with the initial diameter of 25 mm and the initial height of 40 mm. These samples were pressed through forging with various deformation degrees. The deformation degree was calculated with (1). Applying HTTMT determines significant improvement of the HS2-9-1-8 high-speed steel micro-structure compared to the samples that have not benefited from plastic deformation. For the thermo-mechanically treated and oil or air quenched samples, the hardness was
After quenching, the heated steel will cool down. Due to the different rate of cooling, the different types of microstructure will be formed. The formation of pearlite, bainite and martensite determine the physical properties such as hardness, strength and ductility.
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.
Comparing the joints welded with two different heat inputs, concluded that the ultimate tensile strength (UTS) and impact toughness of the welded joints decreases with increases the heat input.
The machinability of copper and copper alloys is improved by lead, sulfur, tellurium, and zinc while it deteriorates when tin and iron are added. Lead in brass alloys with concentrations around 2 wt%, improves machinability by acting as a microscopic chip breaker, and tool lubricant, while they increase the brittleness of the alloy [17]. Lead additions are used to improve machinability. The lead is insoluble in the solid brass and segregates as small globules that help the swarf to break up in to small pieces and may also help to lubricate the cutting tool action. The addition of lead is however, affect cold ductility which may control both the way in which material is produced and the extent to which it can be post-formed after machining
Titanium shows a high strength-weight ratio and has exceptional corrosion resistance. Titanium alloys have received considerable interest recently due to their wide range of applications in the aerospace, automotive and medical industries. The most common titanium alloy is Ti6Al4V, which belongs to the α+ β alloy group. However titanium alloys are difficult to machine due to their low modules of elasticity. Titanium is a poor conductor of heat, its thermal conductivity is about 1/6 that of steel. Heat, generated by the cutting action, does not dissipate quickly; therefore, most of the heat is concentrated on the cutting edge and the tool face [1]. Titanium has a strong alloying tendency or chemical reactivity with materials in the cutting tools and also reacts with oxygen and nitrogen in air at tool operating temperatures. This causes galling, welding, and smearing along with rapid destruction of the cutting tool [1].
Hydrogen reduces load – bearing capability and reduction of ductility, there are several hydrogen sources, it can enter the material as a result of electroplating, and the main source of hydrogen in steel bridge cable wires is hydrogen gas in the atmosphere. Molecular hydrogen is dissociated, which produces atomic hydrogen that then diffuses internally and embrittle’s the metal. Hydrogen diffuses rapidly through the lattice due to its small size this is because hydrogen in the lattice exists as a monoatomic form. Dissolved hydrogen can travel along by moving dislocation in response to applied stress. On a macroscopic scale hydrogen produces a decrease in the prevalence of ductile process in comparison to fracture without hydrogen due to a decrease in stress intensity (2). Cracks grown in hydrogen embrittlement are mostly along slip planes which can be seen as striations. Hydrogen tends to accumulate in lattice, gra...
Deformation of a material or strains depends on the magnitude of stress. For most metals that are stressed in tension stress and strain are proportional Deformation at which stress is proportional to stain is called elastic deformation, a plot of stress versus strain results in a linear relationship. The slope of this linear segment represents to the modulus of elasticity E. This modulus indicates the stiffness of the material or material’s resistance to el...
Equation 3.3 is utilized for the assessment of the structural torsional stiffness of the handle for its design and analysis. This equation is inputted into the spreadsheet and plotted to look for the coefficient. The coefficient is the structural torsional stiffness, KT of the handle. All values needed for the equation are measured from the handle model in SolidWorks.
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]
The purposes of this lab were to determine a relationship between percent cold working and hardness, determine the effect cold working has on microstructure, and last but not least relate dislocation theory to the observed data. Determining the relationship between percent cold working and hardness involved using a cold roller and running our cartridge brass (70 wt.% Cu, 30 wt.% Zn) sample through it until the percent given was reached by each group. This is a good material because it is well suited to cold-forming because of its high strength and ductility. Each group was assigned a specific percent to reach. The percent’s were 0, 10, 20, 30 40, and 50 respectively. After our percent was given a top and bottom were decided and this was so the sample was ran through the same way every time. The percent cold work is found using this equation % CW = t1-t2/t1 * 100, multiplying by 100 to get the percent, t1 is the original thickness of the sample and t2 is the thickness after running it through.
A steel is usually defined as an alloy of iron and carbon with the content between a few hundreds of a percent up to about 2 wt%. Other alloying elements can amount in total to about 5 wt% in low-alloy steels and higher in more highly alloyed steels such as tool steels and stainless steels. Steels can exhibit a wide variety of properties depending on composition as well as the phases and microconstituents present, which in turn depend on the heat treatment.
This can be achieved by machining at the highest cutting speed without affecting tool life, reducing the scrap parts and minimize downtime. During machining process, lots of parameters could affect the cutting condition. Although machining operations can be carried out “dry”, cutting fluids have been used extensively and play a significant role in machining areas. Cutting fluids affect the productivity of machining operations, tool life and quality of workpiece. Also, they prevent the cutting tool and machine from overheating. The proper application of cutting fluids provides higher cutting speeds and higher feed rates (Tazehkandi et al., 2014). A cutting fluid can be defined as any substance which is applied to a tool during a cutting operation to facilitate removal of chips. In the beginning, cutting fluids consisted of simple oils applied with brushes to lubricate and cool the machine tool. As cutting operations became more severe, cutting fluid formulations became more complex. Today’s there are several types of metal cutting fluids (MCFs) that can be extensively classified as straight fluids, petrochemical, synthetic, semi- synthetic fluids, soluble fluids and vegetable based cutting fluids (VBCFs) (Ozcelik et al., 2011). The cutting fluids are composed in their production phase of two components: base fluid and additives. Base fluids are either oil or water. Oil based cutting fluids consist mainly of mineral oil, alternatively synthetic or vegetable oils. Water based fluids can be divided into dilutions and emulsions. The water based dilutions are generally clear and chemically stable fluids composed of water and non-organic and/ or organic substances. A water based emulsion is a milky and stable disperse mixture. For example mineral oil, plant oil ester or animal fat esters can be emulsified into water (Winter et al., 2013). Cutting
P R Babu,Dr T S Prasad, Dr A V S Raju, ‘The Effect of External Roller-burnishing on the Surface Roughness and Surface Hardness of EN 31 Alloy Steel’, IE(I) Journal–MM.
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.
Annealing and tempering are not the same types of heat treatment. Annealing can be defined as heating the steel to aus...