The first metal sample that will be discussed is 4140 steel. This sample was subject to multiple heat treatment processes that included quenching, normalizing, full annealing, and tempering.
The micrographs of the heat treated samples can be seen below in Figure 2.
Figure 2: 4140 Steel Micrographs 100X a) Baseline, prepared by Bryan Biggs b) Quenched, prepared by Cameron Palkowski c) Normalized, prepared by Michael Rodriguez d) Full Annealed, prepared by Avery Callahan e) Tempered, prepared by Kimsour Thach
As one can see above in Figure 2, the different heat treatment processes had a wide variety of effects on the microstructure of the 4140 steel. The baseline 4140 steel micrograph shows the lighter shaded ferrite regions with …show more content…
In the baseline micrograph, the small black areas are concentrated areas of lead that are present with the brass. Once the sample was quenched, the lead concentrations increased in size, which has a detrimental effect to the hardness of the material, since lead is a soft material. In the surrounding area around the lead concentrations, there also appears to be higher concentrations of zinc in the quenched brass micrograph, which is indicated by the darker brass colors. This coincides with the initial assumptions of what would happen to brass when subject to quenching. Since brass has a very lower carbon percentage, it can be expected that quenching will have little to no effect in hardening the brass sample. In this case, the quenching of the brass actually lowered the hardness significantly of the samples. This data is shown below in Table …show more content…
Heat treating steels to increase their hardness strength has been a process that has been done for centuries. In addition to this, reasoning was found for why it is uncommon to see heat treatment in materials with low carbon content, such as low carbon steels (1018 steel) and brass. The results of this experiment coincide with what was expected, and no obvious errors in the experiment were found. One factor of this experiment that could be improved is the quality of the micrographs that were produced. To do this, the metallurgical preparation of the material would need to be done in a much more precise and consistent way. The instructions were clearly laid out, but the execution of the instructions varied too much between individual samples, and consequently produced lackluster images for analysis. In the future, some recommendations to improve the quality of the finished surfaces could be to keep fresh abrasive pads on the ECOMET polishing machines, taking extra care when preparing and handling the etching solutions, and observing the surface finish of the material directly after the etching process is