Deep Cryogenic treatment has had a dramatic effect on the development of wear resistance of steel components. It is a supplement process to the conventional heat treatment process of steels. The aim of the present research work is to optimize the parameters affecting the deep cryogenic treatment process for attaining the minimum wear loss of 4140 steel. The selected process parameters for this optimization study are hardening temperature (A), soaking period (B), tempering temperature(C) and tempering period (D). The optimum levels and the interaction of the deep cryogenic treatment parameters for 4140steel are arrived using L27 Taguchi orthogonal design. The experimental result shows that hardening temperature is the most significant factor in the deep cryogenic treatment process. Moreover, ANOVA analysis shows that the percentage contribution of hardening temperature is 17.34% when compared with the other factors.
Keywords: (A) ferrous metals and alloys, (E) wear; (C) heat treatments
1.0 Introduction
It is a paramount importance to find the deep cryogenic treatment conditions for minimizing wear of steels in the heat treatment industry. Supplementing deep cryogenic treatment to conventional heat treatment process will aid the manufacturers to attain better wear resistance of steel components. Deep cryogenic treatment is an affordable permanent treatment that influences the mechanical properties of the steel components. It alleviates the amount of retained austenite present in the conventionally treated steel [1]. The removal of retained austenite results in an increase in hardness [2-3] and the process of “low temperature conditioning” of martensite, normally at liquid-nitrogen temperatures (-196°C), initiates nuclea...
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Nucor is the world’s largest recycler, recycling over 10 million tons of scrap steel annually. Nucor descended from auto manufacturer Ransom E. Olds, who founded Oldsmobile. The company evolved into the Nuclear Corporation of America, which was involved in the nuclear instrument and electronics business in the 50’s and early 60’s. Over the next five years, Valley Sheet Metal, Vulcraft Corporation and U.S. Semi-conductor Products joined the Nuclear Corporation. After suffering several money-losing years, in 1964 F. Kenneth Iverson was installed as president. Management then decided to integrate backwards into steel making, and in 1972 they adopted the name Nucor. Since then Nucor has established itself as a leader in the steel industry through efficiency and innovation. It now employs more than 7,000 people worldwide and has experienced tremendous growth under its new CEO Daniel R. DiMicco. SWOT Analysis Strengths • Low Cost Producer • Employee/Managerial Relations Leading Innovator • Low Debt Load • Overall industry leader Weaknesses Dependency on scrap metal
Achieving quality of conformance involved conform to specifications that involve providing customers with a quality product at the right price which accounts for the cost of materials. In order for a company to achieve and produce a successful product that customers want and need, it is vital that quality management and lean systems play front row. Quality management helps organizations to reduce waste and inventory. “Lean is about challenging the way things are done and opening our eyes to that waste and inefficiency” (Lean Benefits - Benefits of Lean, Why Lean is Important, 2015). Within each of these concepts are important tool and techniques that organizations can use to achieve a quality product. In this paper I will discuss “cost of quality” from the quality management side and “kaizen’s” from the lean system side, while discussing how each of these concepts are implemented into my own life or
The total quality management is valuable asset for Longxi providing it was an competitive edge over most of other competitors. However Longxi needs to improve the quality control system further to meet industry accept standard, i.e. ISO9002 to expand further into the overseas markets.
Titanic's steel showed high levels of oxygen, which leads to an increased ductile-to-brittle transition temperature. For Titanic's steel, that temperature was determined to be 25 to 35 degrees C [Hill, 1996].
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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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.
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.
In order to ensure quality, a continual quality process will be used throughout the project life cycle. This iterative process includes measuring process metrics, analyzing process data, and continuously improving the process.
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Advanced CNC fabrication tools and 3D printing machines have made notable improvements in the construction industry. The benefits of this new approach have been developed over many years to increase...
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Today many types of drill accessories and tools are used for domestic and commercial tasks. The use of cordless drill accessories prove effective for doing a hole in roofs or walls. In this regard, drill is an ideal item used in many types of applications.
In summary, the rate of cooling from the austenite phase is the main determinant of final structure and properties.