Mechanical Engineering

Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements, their inter-metallic compounds, and their mixtures, which are called alloys.  1.        Introduction 2.        Properties 3.        Occurrence 4.        Uses 5.        Metallurgy 1.        Introduction    Iron or ferrum (latin word)    Elemental symbol: Fe    Atomic number:     26    Elemental group:   Transition element             Uses:              prehistoric ages: ornamental purposes and used as weapons (IRON AGE)    earliest specimen still extant is a group of oxidized iron beads found in Egypt, dates from about 4000 BC. 2.        Physical properties ·          Iron is soft, malleable, and ductile. ·          Iron is easily magnetized at ordinary temperatures; it is difficult to magnetize when heated, and at about 790° C (about 1450° F) the magnetic property disappears. ·          Pure iron melts at abou

NDT (NON DESTRUCTIVE   TESTING) :-  Non Destructive Testing in great variety are in world   wide used to detect variations in structure, minute changes in surface finish, the presence of cracks or other physical discontinuities, measure   the thickness   of materials   and   coatings   and   to   determine  other characteristics of industrial products. REASON'S FOR THE USE OF NDT: "NDT" is used by the manufacturers for the following reasons:  1. To ensure product reliability. 2. To make profit for the user. a)    To ensure customer satisfaction b)   To aid in better product reliability. c)    To control the manufacturing processes. d)   To lower the manufacturing costs. e)    To maintain uniform quality level. SOME OF THE MOST COMMON NDT METHODS ARE : 1.VISUAL   INSPECTION 2.LIQUID PENETRATION TEST 3.MAGNETIC PARTICLE TEST 4.RADIOGRAPHY  

Effects of Alloying Elements:- About twenty different elements are used in various proportions and combinations in the manufacture of both carbon and low alloy structural steels. Some are used because they impart specific properties to the steel when they alloy with it (i.e. dissolve in the iron), or when they combine with carbon, wholly or in part, to form compounds known as carbides. Others are used because they are beneficial in ridding the steel of impurities or rendering the impurities harmless. Still another group is used to counteract harmful oxides or gases in the steel. The elements of this last group act only as fluxes or scavengers and do not remain in the steel to any extent after solidification occurs. Some elements fall into more than one of the above groups. The effects of some of the more common alloying elements are as follows: Aluminum is often used to promote nitriding but its major use in steel making is as a deoxidizer. It may be used alone, as in low ca

Chemical Composition :-  The chemical composition of steel is of great importance since it determines the potential mechanical properties of the finished steel product and controls the degree of corrosion resistance and weld- ability of the material For this reason structural steel specifications always provide a table of chemical composition limits within which the steel producer must develop his own particular recipe. The purpose of the specified chemical composition is not to provide the detailed chemical formula necessary to produce a certain type of steel but to provide safeguards. The steel producer is informed that he must keep within the limits which are deemed to be acceptable for the type of steel considered. Within these limits, which may be broad or narrow, the steel producer has complete freedom to use his skill and knowledge to make steel with the required mechanical properties. Each producer selects a combination of quantities of elements, which fall within the requi

Normalizing :- Normalizing is a heat treatment process used to refine the structure of the steel to improve machinability, tensile strength, structure of weld and to remove cold working strains etc.  Normalizing is often used for ferrous alloys that have been austenitized and then cooled in open air. Normalizing not only produces pearlite, but also bainite and sometimes martensite, which gives harder and stronger steel, but with less ductility than full annealing. The hardness obtained after normalizing depends on the steel dimension analysis and the cooling speed used.  Objectives of Normalizing :-  It produces a uniform structure It improves tensile, impact & yield strength It refines the internal structure to fine grains It removes the internal stress formed during previous operations It improves structures in welds It produces a harder and stronger steel then full annealing  It eliminates the carbide network at the grain boundaries of hyp