Mechanical Engineering

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 ...

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...