Copyright © 2018 KWP Journals. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. International Journal of Engineering Works Kambohwell Publisher Enterprises ISSN: 2409-2770 Vol. 5, Issue 5, PP. 116-119, May 2018 www.kwpublisher.com To Study the Effects of Heat Treatment on the Welded Joints Engr. Mujahid, Dr. Saim Saher, Engr. Zainab Huma Abstract— The present research was undertaken to demonstrate the effects of heat treatment on the welded joints. The material used was mild steel and aluminum. Ten flat tensile specimens, ten mounted specimens for micro structure test were prepared for steel and four flat tensile specimens, four mounted specimens for micro structure. This project is an effort to establish better understanding about the heat treatment of the welded joints. The scope of work includes the preparation of test specimens for tensile testing and micro structure analyses. Keywords— Welding, Pre and Post welded joints, Grain size, Heat treatment, Universal testing machine, SEM, Machining. I. INTRODUCTION Fabricated structures often contain a number of welded sub-assemblies and these sub-assemblies generally contain several welded joints. The welded sections may require the Heat Treatment process to enhance the material properties. For tensile testing, from the first sample four set of specimens are prepared. One specimen is the original mild steel , second is “original heat treated” specimen, third sample is welded initially and then heat treated (pre-weld heat treated) and the other set of sample is heat treated initially and then welded (post-weld heat treated) . A comparison study is conducted on both types of specimens to evaluate the welding distortion and mechanical strength of the welded joints. Same procedure was repeated in the preparation of samples for the rest of two mild steel specimens and one Aluminum sample preparation. For micro structure analyses, four set of samples are prepared for the first sample that is “original sample” “original heat treated sample” “pre weld heat treated sample” and “Post weld heat treated sample”. Specimens for all the samples were prepared in the same fashion. After preparing the specimens, images of their micro structure are taken through scanning electron microscope (SEM). A. Major Equipments Used Heat Treatment Furnace: To perform the heat treatment on the selected and prepared specimen .one set of samples are “pre-weld heat treated” and other set of samples are “post-weld heat treated”. Scanning electron microscope: To take images from each of the mounted specimens to study the micro structure and to observe and analyze the effects of heat treatment on the grain size and structures of the specimens. Universal testing machine (UTM): To perform the tensile testing on different specimens and to study the effects of heat treatment on the tensile strength of the material selected. Lathe machine: The Lathe machine of workshop section of University of Engineering and Technology Peshawar was used for the conversion of raw material into Dog bone specimens. B. Material selection We selected our material as “mild steel strip” and “aluminum bar”. As these specimens are manufactured in the local industries of KPK so in order to find their exact composition we performed EDX analysis in CRL Lab University of Peshawar to find out there composition. Figure. 1 EDX Analysis of Mild steel From the results of EDX analysis we come to know about the composition of carbon which is above 0.8%. If the composition of carbon is above 0.8%, it is Hyper-Eutectoid so the metallurgical formulae are not applicable and we will examine its properties from the morphology of the structure i.e. SEM images. Now it becomes the base of our studies. This analysis has been shown in the Figure 1. II. PREPARATION OF SPECIMEN This section includes preparation of specimens for final tests and inspection .Two different sets of specimens were being prepared .They are: A. Specimens for UTM Engr Mujahid Wasim Durani: U.S Pakistan Center for Advanced Studies In Energy (U.S PCAS-E), UET Peshawar. Dr. Saim Saher: U.S Pakistan Center for Advanced Studies In Energy (U.S PCAS-E), UET Peshawar. Engr Zainab Huma: U.S Pakistan Center for Advanced Studies In Energy (U.S PCAS-E), UET Peshawar.