Stainless Steel Essay

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I. INTRODUCTION
Martensitic stainless steels have good mechanical strength and moderate corrosion resistant. Because of their excellent corrosion resistance and mechanical strength, martensitic stainless steels are used for manufacturing the steam turbine blades, heat exchangers, automotive components and structures, petrochemical & process piping. Properties of martensitic stainless steel can be changed by the heat treatment. Increasing productivity of any welding process while maintaining or even improving the weld quality has been the task of researchers in the field of development of welding processes. Over the years welding methods and techniques have developed to great extent [3]. Now it is feasible to weld starting from thin metal sheets of fraction of mm to very thick plates of virtually any thickness. The quality of welding is not restricted only to work done by the welder but depends on many other factors, viz. welding technique and its parameters, welding equipment shielding medium, working environment, etc.
The heat input rate is one of the most important variables in fusion welding, since it governs heating rates, cooling rates and weld pool size. In the welding of steel, this is important relationship since increased cooling rates increase the risk of hydrogen-induced cracking. The other metallurgical feature that is directly affected by the heat input rate is grain size in the heat affected zone (HAZ) and in the weld metal. In steel welding it is necessary to seek a heat input rate that gives the optimum combination of grain size and cooling rate [11]. Before the actual welding is done, all the earlier steps such as layout, plate edge preparation, fit up and alignment should be well planned with regard to achieving...

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...sed upon the present research work the following conclusions could be drawn:
• The weld joint made using the low heat input possessed the maximum ultimate tensile strength (791.56 MPa).
• It is investigated that in the present experiment work, maximum UTS increased by 38.11 MPa for the joints fabricated with low heat input and subjected to post weld heat treatment.
• Percentage elongation (ductility) of the joint decreased due to the post weld heat treatment.
• From the results of the Charpy V-notch impact test, it is found that the maximum CVN value in as welded condition of low heat input combination is 115 Joule, and it is increased with the post weld heat treatment.
• Comparing the joints welded with two different heat inputs, concluded that the ultimate tensile strength (UTS) and impact toughness of the welded joints decreases with increases the heat input.

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