Steel and its types

Steel and its types Steel is basically an alloy of iron and carbon to which sometimes other elements are added to achieve certain properties for specific performance of the steel. It is the most common material which the people come into contact with every moment, all the day and every day. There is hardly any object that people use today which does not contain steel or which is not created with equipment made of steel. In fact, today it is hard to imagine a life without the use of steel in some shape or form.  One has to just think of what would be missing in everyday life if there is no steel. Mass production of steel started late in the nineteenth century. From that time onwards steel has become the material of choice in most of the applications which make the daily lives of the people possible. This position of steel is due to its versatility, strength, and recyclability. The versatility of steel is well known. It can be used in diverse applications which includes transportation, infrastructure, building structures etc. on one side and sewing needles, screws for laptops, mother board sheets for mobile phones, springs for wrist watches and many others such smaller applications. Ballpoint pens rely on a steel sphere less than 1 mm in diameter to dispense ink. Steel can also be used in a wide variety of atmospheres which include extremes of cold and hot climates as well as in both arid and wet climates. World today depends on the strength of steel. Steel makes it possible to build skyscrapers and long span bridges since it has strength, rigidity and durability. Tankers and bulk carriers which help in moving resources across the world are made of steel. Wind mills...

Cobalt in Steels

Cobalt in Steels  Cobalt (Co) (atomic number 27 and atomic weight 58.94) has density of 8.85 gm/cc. Melting point of Co is 1493 deg C and boiling point is 3100 deg C. At temperatures below 417 deg C cobalt exhibits a hexagonal close packed structure. Between 417  deg C and its melting point of 1493 deg C, Co has a face centered cubic (fcc) structure. Co is a magnetic metal with a curie temperature of 1121 deg C. The phase diagram of the Fe-Co binary system and is given at Fig 1. Fig 1 Fe-Co binary phase diagram Co is not a popular element which is commonly added to alloy steels. It does have some effects but these can also be achieved with other alloying elements such as molybdenum (Mo), and nickel (Ni) etc. at lower costs and mostly with better results. Due to this factor, Co does not find enough use in high tonnage low alloy steel production. However it does have some niche markets in steel. Co becomes highly radioactive when exposed to the intense radiation of nuclear reactors, and as a result, any stainless steel that is in nuclear service will have a restriction in the Co content which is  usually around 0.2 % maximum. Adding agents In the production of co bearing alloy steels, additions of Co during the steel making is made in the form of Co metal which is supplied to steel producers in the form of briquettes, granules, and broken electrolytic cathodes. Content of Co in these additive agents is usually in the range of 98 % to 99.9 %. Scrap of super alloys normally contains high percentage of Ni and hence is not used for the production of tool steels. However this scrap can be used...