Duplex Stainless Steels...

Duplex Stainless Steels  Duplex stainless steels belong to the stainless steels family and are characterized by high chromium (Cr, 19 % to 32 %) and molybdenum (Mo, up to 6 %) and lower nickel (Ni) contents than austenitic stainless steels and identified by a dual phase micro structure. They have a well balanced two phase structure. The two phases in their microstructure consist of grains of ferritic and austenitic stainless steels. The microstructure contains roughly 50 % austenite and 50 % ferrite. Commercial duplex stainless steels may have 30 % to 70 % austenite and 70 % to 30 % ferrite. Fig 1 shows micro structure of duplex stainless steel.  Fig 1 Micro structure of duplex stainless steel  Duplex grades account for less than 3 % of global stainless steel production, however with a strong growth rate.  They are most commonly used when a combination of high mechanical strength and high corrosion resistance is required. The idea of duplex stainless steels dates back to the 1920s with the first cast being made at Avesta in Sweden in 1930. These first generation duplex stainless steels provided good performance characteristics but had limitations in the as welded condition. The heat affected zone (HAZ) had low toughness because of excessive ferrite and significantly lower corrosion resistance than that of the base metal. The second generation duplex stainless steels are defined by their nitrogen (N) alloying. This new commercial development began in the late 1970s. With this the duplex steels have begun to ‘take off’ in a significant way. This is mainly due to advances in steelmaking techniques (AOD process) particularly with respect to control of nitrogen (N) content. The interactions of the major alloying elements, particularly the Cr, Mo, N, and Ni, are quite complex. To achieve a...

Cost Control during Production...

Cost Control during Production  The broad definition of costs is related to the economic resources necessary to accomplish work activities or to produce work outputs. Usually, costs are expressed in terms of units of currency. Therefore, costs are the amount of money representing the resources spent for the production of output. A resource is a physical entity that is required to be able to execute a certain operation. Resources can be e.g. machine and equipment, raw materials, utilities, tools, fuel and energy, but also operators and consumables. Outputs are the products and byproducts. The success of an organization largely depends on the profit that it can realize. The profit is determined by the costs that are made and the extent to which these costs are recovered. Therefore, it is essential for the organization to know all the costs so that it is able to control them. Cost control is a managerial effort to attain cost goals within a particular environment. Cost control is not a specific program. Rather, it is a routine activity carried out continuously. Cost must be controlled; otherwise, there will be wastage and misappropriation. Cost control is an important activity for any efficient organization since it has a major impact on the profitability of the organization. The costs throughout the entire organization are to be known to the management so that it can be used for the purpose of decision making. Therefore, it is necessary to integrate the cost information in the management process. For this a system is needed that can support the management with the cost data and hence in controlling the cost. According to Liebers the cost control component can be broken into four functions namely cost estimation, production monitoring, cost calculation and evaluation, and cost modeling. The...

Bar, Rod and Wire Drawing May26

Bar, Rod and Wire Drawing...

Bar, Rod and Wire Drawing  Drawing is a metal working process that forms steel work piece by reducing its cross section. This is accomplished by forcing the work piece through a die of smaller cross sectional area than the work piece. In the process of drawing the work piece is pulled through the die by means of a tensile force applied at the exit end of the die. When steel work piece is drawn, it is drawn at room temperature.  At that point, it is being cold worked or cold forged. Due to the cold working during drawing, geometric and mechanical characteristics of the steel material gets changed, transverse dimensions get reduced (e.g. diameter) and length get increased with no change in volume (waste free processing). As a result of plastic deformation in the drawing die, steel material gets also strengthened which means an increase in strength properties and decrease in plastic properties.  Deformation in drawing is influenced by a number of factors, out of which chemistry, strength of material, temperature, approach angle, lubrication, drawing speed, co efficient of friction, die life and wear, and reduction of area are the most significant. Wire drawing is primarily the same as bar drawing except that it involves smaller diameter material that can be coiled. It is generally performed as a continuous operation on the draw bench. The process of wire drawing has changed very little over the years.  It uses a combination of a die and/or a series of dies to draw wire to a selected gauge. The principle of the process is shown in Fig 1.  Fig 1 Drawing process principle  The drawing process has the following objectives Manufacturing drawn products in the form of bars or wires to a very specific and precise cross...

Ductile Cast Iron

Ductile Cast Iron  Ductile cast iron also known as nodular cast iron, spheroidal graphite iron or SG iron, and spherulitic cast iron. The ductile iron process was developed by The International Nickel Company in 1948. As the name ductile iron suggests this grade of cast iron has a degree of ductility. The main characteristic of this material is the structure of the graphite. Ductile iron is a family of cast graphitic irons which possess high strength, ductility and resistance to shock. Annealed cast ductile iron can be bent, twisted or deformed without fracturing. Its strength, toughness and ductility duplicate many grades of steel and far exceed those of standard gray irons. Yet it possesses the advantages of design flexibility and low cost casting procedures similar to gray iron. The difference between ductile iron and gray iron is in the graphite formation. Ordinary gray iron is characterized by a random flake graphite pattern in the metal. In ductile iron the addition of a few hundredths of 1 % of magnesium or cerium causes the graphite to form in small spheroids rather than flakes. These create fewer discontinuities in the structure of the metal and produce a stronger, more ductile iron. This nodular graphite structure inhibits the creation of linear cracks hence the ability to withstand distortion. Fig 1 shows typical micro structure of ductile iron. Fig 1 Typical micro structure of ductile iron  With ductile iron, the safety and reliability of process equipment is improved. The improved mechanical properties increase its resistance to breakage from physical load, or mechanical and thermal shock far above that of gray iron. The corrosion resistance of ductile iron is equal or superior to gray cast iron and to cast steel in many corrosives. Its wear resistance is comparable to...

Management Information System...

Management Information System  Management information system (MIS) is a planned system for collecting, storing, and disseminating data in the form information needed to carry out the functions of the management. It provides information that organization requires to manage itself efficiently and effectively. MIS deals with information related to technologies, processes, operation, personnel, areas, and other things, within an organization and in the environment surrounding the organization. Information means data that have been shaped into a form that is meaningful and useful to the management and employees of the organization. Data, in contrast, are streams of raw facts representing technologies, processes, operation, personnel, areas, and other things occurring in organizations or the physical environment before they have been organized and arranged into a form that management and employees can understand and use. Typical features of an MIS is shown in Fig 1 Fig 1 Typical features of an MIS  Management information system can be defined technically as a set of interrelated components that collect (or retrieve), process, store, and distribute information to support decision making, coordination and control in an organization. In addition to supporting decision making, coordination, and control, MIS may also help management and employees to analyze problems, to visualize complex subjects, and to bring forward new solutions. Management information system is also defined as an information system that evaluates, analyzes and processes an organization’s data to produce meaningful and useful information on which the management takes right decision to ensure success and future growth of the organization. As per another definition MIS is an information system that provides information in the form of standardized reports and displays for the management. MIS is a broad class of information systems designed to provide information needed for effective decision making.  The three components in MIS gives...