A demonstration of heat affected zone from welding

Heat effects on base metals caused by welding are often described to students in courses in manufacturing, design, or materials. An example where students may measure these effects was developed, is presented here, and is intended for programs and students who prefer to learn from concrete examples, as is typical of many engineering technology students. Description of situations where heat effects may be deleterious are provided to place this work in the context of welding operations. Presented in this paper is a simple demonstration of heat effects from welding, using commonly available materials and equipment, which allows students to measure changes in material properties. Significant changes in material properties have been achieved by butt welding two socket-head cap screws end to end, then measuring Rockwell hardness values incrementally from the weld out to the ends of the part. Sample preparation, welding, and measurements for this demonstration could easily be assigned to students in its entirety. An approximate finite element analysis of the heat applied during welding of the demonstration part, and the material changes that should be expected as a result of the welding operation are included. This demonstration combines several elements of the desired accreditation criteria program outcomes, drawing upon and extending student knowledge of manufacturing processes, materials, and thermal sciences. Possible extensions to this demonstration are also presented.