Nitrogen and Steels

Nitrogen and Steels Nitrogen (N) (atomic number 7 and atomic weight 14.008) has density of 1.25 gm/litre at standard temperature and pressure. Melting point of N is -210 deg C and boiling point is -195.8 deg C. The phase diagram of the Fe-N binary system is at Fig 1. Fig 1 Fe-N phase diagram N is present in all commercial steels. Since the of concerns of presence of N in steels are normally small and its analysis being complex and expensive, its existence is generally ignored even in steel specifications in various standards. However, whether present as a residual element or added deliberately as an alloying element, the effects of N in steel are significant.  N is an important and inexpensive alloying addition to steels. In recent years there has been an increasing demand to reduce and control the amount of dissolved gases in steel. N is one of the important gas which when dissolved in liquid steel affect its properties significantly. Hence control of N content of steels during steelmaking is important. N in steel can be in its uncombined form as free N or in the form of a compound or nitride. Steel from an electric arc furnace (EAF) normally has higher N levels (70-110 ppm) compared to that produced in a basic oxygen furnace (BOF) where N varies between 30 and 70 ppm. Hence, N is of particular importance in an EAF plant. In certain stainless steel grades the amount of N can be at the level of 3000 ppm. N levels in degassed steels can be below 10 ppm.  N exists in steel as an interstitial quite similar to, but much more soluble than, carbon (C) and as nitrides of iron (Fe), aluminum (Al), vanadium (V), niobium (Nb), titanium (Ti),...

Creating Sustainable Future for Excellence...

Creating Sustainable Future for Excellence  An organization can achieve sustainable excellence if it embraces and respects the environment in the present and cares for the well being of the  generations to follow. The concept of creating sustainable future is broadly defined as meeting the needs of the present generation without compromising the ability of future generations to meet their needs. The ability to adapt to change is a crucial element for the survival and the key to success for an organization. The critical issue of the present time is the ability to sustain  in the face of rapid global change and resource competition. Everyone including employees and stakeholders are to play a part for creating a sustainable future. Management is to practice transformational stewardship and to find sustainable practices and strategies for the organization to create sustainable future. The principles adopted by the organization creating sustainable future are more holistic than the practices followed in the past. The management is to recognize that both the need for return on investment, the wise use of resources, and seeking the well being of their employees and stakeholders are equally important. The organization creating sustainable future is to utilize appropriate technologies and strategies for securing its future and to benefit its neighborhood. It is to shift towards the practices that respect people, profit and planet to remain not just competitive, but secure in the market. Organization creating sustainable future take managerial decisions which are based not only on financial concerns but also on environmental and social concerns. Such organization (i) creates long term financial value, (ii) knows how its actions affect the environment and actively work to reduce their impacts, (iii) cares about its employees, customers, communities, and other stakeholders and work towards making positive social changes,...

CLU process for Stainless Steel Production Dec28

CLU process for Stainless Steel Production...

CLU process for Stainless Steel Production Stainless steel production process has some basic features such as carbon (C) removal, deoxidation and desulphurization. In the production process, these operations are generally combined with some alloying with solid material as well as nitrogen (N2) control.  These requirements are met in different ways in various processes being deployed for the production of stainless steel. The CLU process is similar to the AOD (argon oxygen decarburization) process for making stainless steels. CLU refers to the Creusot-Loire Uddeholm process for stainless steel production. It also uses liquid steel from an electric arc furnace (EAF) or any other similar primary steel making furnace.  The major impetus for the development of the CLU process was the idea to use superheated steam as the diluting gas instead of argon (Ar) gas which is used in the AOD process. Superheated steam has been used as a process gas in stainless steel production since the early 1970s when this technology was developed at Uddeholms Degerfors steel plant in Sweden. In France a similar development took place within the Creusot-Loire group. The developed process was named Creusot Loire Uddeholm (CLU) process. The converter originally used in CLU process was a bottom blown converter thus differentiating it from the side blown AOD converter. However, presently CLU process with the use of a side blown converter is also available. The first commercial plant using the CLU process was built in 1973 by Uddeholm. Between 1973 and 2003 stainless steel was produced in Uddeholms Degerfors steel plant in an 80 ton converter where superheated steam, Ar, N2, oxygen (O2) and compressed air were used as process gases. The converter in the Degerfors steel plant was operated for 30 years as a CLU process for stainless steel production before...

Lime and Calcined Dolomite for Use in Steel Plant...

Lime and Calcined Dolomite for Use in Steel Plant Lime is a versatile compound.  Various forms of lime are used in environmental, metallurgical, construction, and chemical/industrial applications etc.  The largest single use of lime is in steel manufacturing, where it serves as a  flux for removing impurities (silica, phosphorus, and sulphur) during refining of steel. The fastest growing use of lime is in environmental applications, where lime is used for treatment of flue gases, wastewater, solid waste, and drinking water. Lime is a white crystalline solid with a melting point of 2572 deg C. It is a basic oxide and is used to react with the acidic oxides (e.g. silica) in various smelting operations. With water it makes milk of lime used for neutralizing acidic waste water. It is also being known as quick lime, lime flux, unslaked lime, and fluxing lime. Lime having some percentage of MgO (usually 2 % to 4 %) is also known as dolomitic lime. Lime is a hygroscopic material and absorbs moisture from the air. With the absorption of moisture it loses its reactivity and gets hydrated. Lime is calcium oxide (CaO) produced on heating (calcination) of limestone (CaCO3) to a temperature of 900 deg C and above (usually 1100 deg C). CaCO3(s) + heat = CaO(s)  +CO2(g) This reaction is reversible. Calcium oxide reacts with carbon dioxide to form calcium carbonate. The reaction is driven to the right by flushing of carbon dioxide from the mixture as it is released. Hydrated lime [Ca(OH)2] is formed by reaction of lime with water (slaking). CaO + H2O = Ca(OH)2 + heat Hydrated lime is also known as slaked lime. It is in the form of a dry white powder. Hydrated lime is an alkali and used for neutralizing acidic solutions. In...

Building Organizational Capabilities for Excellence...

Building Organizational Capabilities for Excellence  Organizational capabilities are rapidly becoming recognized as important keys for the organizational success. Today developing new capabilities is a strategic necessity for an organization. The organization confronts many challenges while developing new capabilities for addressing the demands and opportunities of the present day ever-changing environment. Organizational capabilities entail extensive learning process dispersed across complex activity fields that even extend beyond the activities of the organization. Organizational capabilities are concerned with the ability of the organization to combine different types of resources, especially organization specific knowledge embodied in the employees, in order to create new resources that enable the organization to achieve and sustain its competitive advantage. Organizational capabilities are viewed as a type of strategic resource since it is rare, valuable, inimitable, non-tradable, and non-substitutable. Organizational capabilities focus on the ability of the organization to meet customer’s demand and the aspirations of the stake holders. In addition, organizational capabilities are unique to the organization so as to prevent replication by the competitors. These capabilities are anything that the organization does for improving its performance and differentiating it from other competing organizations. Developing and cultivating organizational capabilities can help the organization to gain an advantage in its operating environment by focusing on the areas where it excels. There are several definitions of organizational capabilities. Some of these definitions state that the organizational capabilities are ‘an all round quality …’ (Stephenson, 1999), ‘ability… to effectively meet… business objectives’ (ANAO, 2001), ‘a process of examining an organization to increase its capacity…’ (Haertsch, 2003), ‘capacity… to deploy existing resources to perform some task’ (Grant, 2004), ‘the embodied knowledge set that supports competitive advantage …’ (Gill & Delahaye, 2004), ‘often referred to as organizational competences, although strictly a capability refers to the potential and...