Micro-Hardness Testing Lab Report

-uter system connected to the machine were set up to gather the information about the gauge length and width of the specimen. The tests were performed at a 2 mm/min. The samples were connected to the clamps of the machine from the both sides. Afterwards, the tensile forces were applied from the ends and the overload failure mode was examined. Furthermore, the test results were measured as the area under the load-displacement curve up to the peak load. The failure mode was determined from the failed samples.
2.3 Metallography
The macroscopic examination also termed as macro test were used to assess the quality and consistency of a test samples representing the flow of material during the welding procedures. Macro tests were achieved at 10x magnifications.
The micro-hardness test can measure the case to core depth parts. Micro-hardness testing is required where the superficial hardness test is not conceivable due to material’s small geometrical shape. The welded part we were going to examine, experienced the similar criteria since the welded bead of the joint was way too small. To test the hardness of our welded area we had gone through a micro-hardness test using a Shimadzu micro-vicker hardness testing machine. In the following practise, we used a micro-vicker tester consists of a square-based diamond pyramid indenter by applying a controlled pressure for a standard length of time with a 100gm load. The indent was made 50 micro metre away from the weld centreline for the galvanized and stainless steels. The diagonal of the resulting indention was measure on a microscope.
interfacial fracture and nugget pull-out as shown in the Fig. It is quite evident from the experimental outcome that welding current is the most significant parameter in resistance spot welding. Welding current significantly affects the mode by which the spot weld fails. It is also noted that increase in the welding current significantly affects the load carrying capacity of the spot welds which can be seen in Fig. This happens because of increase in size of the Fusion Zone (FZ) as it is evident from the literature that the fusion zone is the most important physical aspect in controlling the failure mode as well as some other mechanical properties of resistance spot welding. Fusion Zone increases as the welding current increases because of more generation of heat at the interfaces of the two sheets. It is quite evident after the static tensile-shear test that at low welding current (>8kA) the overload failure mode of the spot welds was interfacial fracture but as soon as the current is increased and subsequently FZ is also increased, overload failure mode changes from interfacial fracture to nugget pull-out as shown in