Corrosion of Cast Irons...

Corrosion of Cast Irons Cast iron is a standard term which is used for a large family of alloys of ferrous materials. Cast iron is mainly alloy of iron (Fe) which contains higher than 2 % of carbon (C) and more than 1 % of silicon (Si). Low cost of raw materials and relative ease of production make cast iron the last cost engineering material. Cast iron can be cast into intricate shapes since it has excellent fluidity and comparatively low melting point. It can also be alloyed for improvement of corrosion resistance and strength. With suitable alloying, the corrosion resistance of cast iron can equal to or exceed that of stainless steel and nickel (Ni) based alloy. Since outstanding properties are obtained with this low cost engineering material, cast iron finds extensive use in atmospheres which need good corrosion resistance. Services in which cast iron can be used for its good corrosion resistance include water, soils, acids, alkalis, saline solutions, organic compounds, sulphur compounds, and liquid metals. In some cases, alloyed cast iron is the only economical choice for the equipment manufacture. Cast iron and the basic metallurgy The metallurgy of cast iron is similar to that of steel except that Si in sufficient quantities is present to necessitate use of the Fe-Si-C ternary phase diagram rather than the simple Fe-C binary diagram. A section of the Fe- Fe3C (iron carbide)-Si ternary diagram at 2 % Si is shown in Fig 1. Iron carbide is also known as cementite. The eutectic and eutectoid points in the Fe-Si-C diagram are both affected with the introduction of Si into the system. With normal Si in the range of 1 % to 3 % in cast irons, eutectic C percentage is related to Si percentage as...

Management of an Organization and Management Techniques...

Management of an Organization and Management Techniques Management of an organization is not a simple activity. On the contrary it is quite complex. Both internal and external factors affect the organizational functioning. Further there are several areas and elements which are required to be managed. Sometimes functioning of an area may appear to be in conflict with the functioning of other area. Smooth functioning of the organization depends on how the management of these different areas and elements are conducted. There are specific management techniques for each area and element. There are other techniques which may encompass entire organization. If these techniques are followed, it aids the proper and healthy functioning of the organization. Management of an organization (Fig 1) can be broadly divided into two areas. These areas of management are (i) management of organizational internal elements which have impact on the organizational functioning, and (ii) management of organizational functions where the organization comes in contact with external agencies. Internal organizational elements for management normally include (i) operational management which is the key to the existence of the organization, (ii) financial management for making the organization healthy financially, (iii) human resource management which deals with the management and development of the employees, (iv) management of organizational future which takes care for the future of the organization in the context of fast changing environment, and (v) management of safety, security and welfare which takes care of the employees’ safety, protection of the organizational properties and the external needs of the employees. Organizational functions involving external agencies are (i) sales and purchase functions involving customers and suppliers, (ii) complying with regulations and laws where the organization comes in touch with regulatory authorities and government, (iii) societal functions where the organization comes in touch with society,...

Probes, Instruments and measurements for Monitoring of Blast Furnace Jun28

Probes, Instruments and measurements for Monitoring of Blast Furnace...

Probes, Instruments and measurements for Monitoring of Blast Furnace A blast furnace (BF) works with the principle of countercurrent gas to solid heat exchange from tuyere raceway to the stock line and of a countercurrent oxygen (O2) exchange from fusion zone to the stock line. Solid burden materials consisting of ferrous materials (iron ore, sinter, and pellets), coke, and fluxing materials are charged into the top of the furnace, while air normally enriched with O2, and sometimes with auxiliary fuels is fed through the tuyeres near the bottom of the furnace. The usual retention time of the ferrous burden materials in the furnace may be as long as 8 hours, while that of the gas is a few seconds. However, the residence time of the coke in the hearth is much longer usually ranging from 1 week to 4 weeks. The liquid hot metal (HM) and liquid slag are tapped at regular intervals through a number of tapholes situated at the bottom of the furnace. The slag is separated from the hot metal which is handled through HM ladles. A blast furnace need to be operated with high productivity and low fuel rate in a flexible, stable and high efficiency manner and must have a long campaign life. The blast furnace is often referred to as black box because of the terms such as the furnace condition and furnace heat level which is currently in dominant use as well as since the blast furnace process has many unknown areas. The reason seems to be due to the difficulty in measurement, because, in a blast furnace, three phases of gas, solid, and liquid coexist, the reaction proceeds non-uniformly in radial direction, the process is accompanied by a time dependent variation, and the parameters to be...

Corrosion of Alloy Steels...

Corrosion of Alloy Steels Alloy steels consists of a group of steels which shows mechanical properties superior to those of ordinary carbon (C) steels as the result of additions of certain alloying elements such as chromium (Cr), nickel (Ni), and molybdenum (Mo) etc. Total content of the alloying elements can range from 0.5 % to 1 % and up to levels just below that of stainless steels. For many alloy steels, the primary function of the alloying elements is to increase the hardenability in order to optimize mechanical properties and toughness after heat treatment. However, in some cases the addition of the alloying elements is used to reduce atmospheric degradation of the steel under certain specified service conditions. Alloy steels are used in a broad range of applications. In some cases, corrosion resistance is a major factor in the selection of alloy steels, while in other applications; it is only a minor consideration. The information available on the corrosion resistance of alloy steels is end use oriented and often addresses rather specialized types of corrosion. Many applications use steels with a rather low content of the alloying elements, high strength low alloy (HSLA) steels, and structural alloy steels. Small additions of some alloying elements usually enhance corrosion resistance in moderately corrosive environments. However in severe environments, the corrosion resistance of this group of steels is often no better than that of C steels. Certain applications need more highly alloyed steels which, in addition to achieving the required mechanical properties, provide increased resistance to specific types of corrosion in certain environments. In this group of steels, corrosion resistance is also an important factor in alloy design. Corrosive environments and the use of the alloy steels Atmospheric corrosion is a factor in nearly all applications of...

Mergers and Acquisitions...

Mergers and Acquisitions An organization may grow its operations either by internal expansion or by expanding externally. In the case of internal expansion, the organization grows gradually over time in the normal course of its operation, through acquisition of new assets, advancement of technology, replacement of the technologically obsolete equipments, and addition of the new lines of products. On the other hand in case of external expansion, the organization acquires either a running organization or a unit of the running organization and grows overnight through corporate combinations. These combinations are in the form of mergers, acquisitions, amalgamations, and takeovers and have become important features of organizational restructuring. These combinations play an important role in the external growth of the organization. Besides the external growth, these combinations also take place because of the marketing strategy of the organization. Mergers and acquisitions (M&A) is a general term which is used for the consolidation of organizations or the assets. The terms ?merger? and ?acquisition? are often uttered in the same breath and are used as though they are synonymous, but both of these terms mean slightly different things.  Over the past decade, M&A have reached unprecedented levels as organizations use corporate financing strategies to maximize shareholder value and create a competitive advantage. ?One plus one makes three? is the equation and the special alchemy of a merger or an acquisition. The key principle behind taking over another organization is to create shareholder value over and above that of the sum of the two organizations. Two organizations together are more valuable than two separate organizations. This is the main reasoning behind M&A. This rationale is particularly attractive to organizations when times are tough. Strong organization acts to take over other organizations to create a more competitive, cost-efficient organization. The...