Tool steels are utilized on a wide variety of application including forming, shearing, cutting and molding (manufacturing the tools, dies, and molds) where (due to their remarkable properties) high wear resistance, hardness, strength, toughness, heat resistance and other properties are preferred for optimum performance. In addition to alloying, tools steels are considered special because they are very difficult to manufacture and require careful manufacturing in every processing step. The very high alloy content and special microstructure that make them desirable for severe applications also make them difficult to manufacture [ , ].
High-carbon, high-chromium (AISI D series) cold-work tool steels are of the main groups of tool steels which are identified with their high wear resistance and exceptional nondeforming properties. The excellent wear resistance of D-type cold-work tool steels is the result of their high chromium (~12wt.%) and high carbon (1.5 to 2.35wt.%) contents.
Generally, the high-carbon, high-alloy tool steels are particularly difficult to process by the conventional ingot metallurgy route. The main challenge is that the relatively slow cooling of the conventional static cast ingot allows the formation of coarse eutectic carbide structures, which are difficult to break down during hot working [1, ]. For overcoming these problems some new processing methods such as powder metallurgy (PM) and spray forming have been developed for production of the most highly alloyed tool steels, such as high-carbon, high-chromium (AISI D series) and high-speed (AISI T and M series) [1, , , ]. These techniques offer the possibility to produce steels with higher homogeneity, lack of segregations, finer microstructure and uniform d...
... middle of paper ...
... Li, Effect of Ca-Si agent modifier on the granulation of γ+(Fe,Mn)3C eutectic particle in an austenite steel, Journal of Materials Science, Vol. 39, No. ?, pp. 1527–1530, 2004.
B.A. Migachev, Effect of niobium on the mechanical properties of steel 9Kh2MF, used for fabricating forming rolls, Metal Science and Heat Treatment, Vol. 43, No. 3–4, pp. 103-106, 2001.
X. Zhi, J. Xing, H. Fu, B. Xiao, Effect of niobium on the as-cast microstructure of hypereutectic high chromium cast iron, Materials Letters, Vol. 62, No. 6-7, pp. 857–860, 2008.
D. Li, H. Lin, H. Chen, Study of hypereutectic high-chromium cast iron containing niobium, Mater Mech Eng, Vol. 6, No. ?, pp. 13–6, 1993.
S. Kheirandish, A. Noorian, Effect of niobium on microstructure of cast AISI H13 hot work tool steel, Journal of Iron and Steel Research, International, Vol. 15, No. 4, pp. 61-66, 2008.
We use metals to construct all kinds of structures, from bridges to skyscrapers to elevators. The strength as well as durability of materials that are crafted out of metal make the materials ideal not only for construction but also for many other applications.
According to recent statistics, zinc is the third most commonly used nonferrous metal in the United States. This unassuming metal was among the first minerals exploited by Man, used as a decorative material for thousands of years, although it never achieved the fame and notoriety of other metals such as gold or silver. In more recent times, new extraction and processing methods have allowed Man to produce higher-quality zinc than ever before, and to use it in an astonishingly high number of chemical and high-tech applications.
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
Nucor is the second largest steel producer (2nd in assets, 1st in profits) in the United States. Its profits of $123 million have made it one of the most efficient firms in the steel industry. Nucor achieved that position by focusing on the manufacturing segment known as mini-mills - the relatively small, electrically-powered mills that melt down scrap steel to manufacture products. This process saves on costly labor, raw materials, and the capital-intensive machinery necessary to produce steel from iron ore. A major concern of mini-mill steel manufacturers is maintaining quality, since their raw material consists of scrap steel of varying quality, containing a variety of alloys and impurities. Another concern it the recent rising price of scrap steel.
-Developed and implemented strip casting overseas to eliminate a step in the steel making process
Group IIAB Iron meteorites have low concentrations of nickel compared to other iron groups. The structures vary from Hexahedrites to coarsest octahedrites. Hexahedrites have the lowest concentration of nickel in their structure. IIAB iron meteorites are thought to be highly reduced materials due to the absence of phosphates, low concentration of nickel and the occurrence of graphite [H]. Group IIIAB Iron meteorites are the largest group of Iron meteorites. Meteorites in this category have medium octahedrite structure (most common iron meteorite structure due to certain amount of Nickel concentration). IIIAB iron meteorites are thought to be oxidized materials due to the high abundance of phosphate [H]. Group IVA Iron meteorites are the third largest group and exhibits octahedrite structures. This group of meteorites has an unusually low ratio of Ir/Au. Apart from this the meteorites are not very volatile [H]. Group IVB iron...
Bessemer process is the method for making high quality steel quickly and cheaply by blowing air into molten iron to remove impurities. Steel’s uses are numerous and widespread, and it is used in industries from agriculture to technology. “… [Henry Bessemer] invented the Bessemer converter and the so called Bessemer process, from which molten iron could be transformed into high-quality steel quickly and in large quantities” (Finnigan 114). The Bessemer process for creating steel has had a massive effect on our culture, economy, and geography.
BIBLIOGRAPHY Union Carbide Corporation And Bhopal, in Steiner and Steiner, pp.147-161.
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...
Advancement of processing techniques in late 1960s and early 1970s led to the fabrication of modern duplex steels. Introduction of vacuum and argon oxygen decarburization (VOD and AOD) was the main factor that led to this massive development in duplex steels during this period. By the advancement of these techniques it was possible to achieve steels with low carbon content mixing with high nitrogen and chromium contents in balance with austenite and ferrite. This eliminated lot of shortcomings in old duplex steels. The alloy content provided a resistant to corrosion while duplex microstructure contributed to prevent chloride stress cracking under severe conditions. And these duplex steels possessed good weld ability also.
...mpositional control needed and also the reactivity of the titanium. Fatigue failure has been known to occur with nitinol because of the extreme amounts of fatigue strain that it is necessarily exposed to. This is because it is still not completely defined how durable nitinol is, so it cannot be known what to use it for as it is the best of all metals known in this case. So it is used for the highest demanding applications but in some cases it can’t handle the pressure sustained. Another use for nitinol is a temperature control system, which would work by changing shape can activate a variable resistor or switch which would control the temperature, this is a situation where it is very significant for nitinol to be a smart material otherwise this system would simply just not work. There are many others but they are not really relevant to the engineering industry.
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.
Maraging steels of different compositions have been prepared by means of induction furnace electro slag remelting technique using titanium and chromium instead of cobalt which is a high expensive strategic element, also nickel content was reduced to 10-13%. Mass attenuation coefficients, half value layers and effective atomic numbers have been determined for the prepared samples at photon energies 238, 583, 661, 911, 1173, 1332 and 2614keV. The results are compared with the corresponding theoretical calculations. In addition, the hardness has been determined for the investigated steels. High nitrogen free nickel steel and carbon steel samples have been also investigated for the sake of comparison. The achieved results reveal the superiority of cobalt-free maraging steels comparing with the other investigated high nitrogen free nickel and carbon steels to be used as a proper shielding material in the nuclear domain. Among the investigated cobalt-free maraging steels, a steel of constituent's "0.05%C-13.26%Ni-2.15%Cr-4.3%Mo-0.02%Ti-0.01%V" has the best attenuation properties. The obtained results are useful for potential applications of these alloys in industrial and nuclear applications.
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.
In summary, the rate of cooling from the austenite phase is the main determinant of final structure and properties.