DiGiannoHeatTreatment

docx

School

New Jersey Institute Of Technology *

*We aren’t endorsed by this school

Course

215

Subject

Mechanical Engineering

Date

Jan 9, 2024

Type

docx

Pages

Uploaded by CorporalSnow2799

Mechanical Engineering Laboratory New Jersey Institute of Technology Report Submitted by Michael F. DiGianno Experiment No. 6 Date Performed 10/31-11/07/23 Date Submitted 11/14/23 Course & Section ME215-101 Instructor Naruemon Suwattananont Heat treatment Experiment Title Performed by Group 101b With TA Md Sojib Kaisar Group Members Michael D Bauly S Yahia Elmanier Marta D Stephen M Jonathan G Braeden G

Table of Contents Abstract 3 Introduction 3 Objectives 3 Background and importance 3 Procedure 3 Original Data Sheet 4 Results and Calculations 6 Discussion 8 Conclusion 8 Questions and Answers 9 Appendix A 9 2

Abstract This is the lab report for experiment six, known as the heat treatment lab. This lab is designed to demonstrate to students the process and results of heat treatment. This lab was split into two weeks. The lab mainly consisted of testing the hardness of samples before and after heat treatment, as well as tempering and annealing. Although our results are dubious, we seem to have validated which heat treatments increase or decrease hardness. Introduction Heat treatment is a very common procedure. Its variations and effects are present in many fields and products. Being familiar with how techniques like tempering and annealing affect the the mechanical properties of the metal is very important as certain processes must be used to achieve desired results Objectives Students participating in this lab should be able to understand and predict the mechanical properties of samples that have undergone various different types of heat treatment. Students should be able to operate a rockwell hardness tester and be able to interpret the reading of the tester. Students should also be able to safely operate a furnace. Background When heat treating these samples we are primarily moving the sample on the iron carbon phase diagram. “The most important alloying element in steel is carbon. Its presence is largely responsible for the wide range of properties that can be obtained and make this metal such a highly useful commodity in everyday life” (Karl-Erik Thelning, 2000) So it's important to know how to move a material to various spots on the graph. Procedure This lab is split into two weeks, although both weeks follow a similar procedure. Students are to obtain low and high carbon steel samples, then test their hardness. These data values are to be stored for future reference. The samples will then undergo heat treatment at various temperatures with different quenching techniques. The samples are then retested for their hardness. This should give students an idea of how various techniques affect mechanical properties. 3

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

Original Data Sheet 4

Results and Calculations 6

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

Discussion When we zoom out and look at all of our results as a whole, they seem quite accurate, but as we look closer things begin to get fishy. I would not go out right to say that I reject any of the results, but some of the data gathered goes against what we generally know to be true with the sample and heat treatment at large. The most egregious is the low carbon samples becoming softer after heat treatment. There are a few reasons that this could be occurring. The first is unlikely, but perhaps the samples were improperly heated. We have no specific reason to doubt the furnaces, but it's worth mentioning that. Some of the samples were sanded down, and we are unaware of what improper sanding would do to the results. The air cooled sample was not let cool all of the way. Prof. used water to finish the cooling process, this may have impacted the results slightly. There are some more reasons that our results may deviate from the expectations.We had various different people taking the measurements. There is a strong possibility that some of them may have used an amount of force that did not correlate with an accurate measurement. There is also a possibility that some of the samples were mixed up. They swapped hands several times and in the lab things can happen. Conclusion Using our results we can draw some conclusions. Judging by the first round of quenches, it seems that a significant increase in hardness requires a high heat as we only see this result in the samples that have been heated to 960C. Although it may be hard to see there is a trend in the harness with quenching mediums. Air provides the lowest hardness of all the mediums. This trend is formed from the medium's speed at pulling thermal energy out of the sample. We also see an evident trend when observing the hardness values after tempering. The higher temperature that we temper at, the more ductile properties get returned to the material. After reviewing our results, we can conclude that the general trends follow the iron carbon phase diagram, and when prompted group members would be able to suggest processes for attaining certain mechanical properties. Furnaces were operated with no mishaps, but due to the multitude of people operating the Rockwell hardness tester there may have been variation introduced into the data. 9

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

Questions and Answers 1. A very hard and brittle version of iron and carbon, it is archived with a specific austenite quenching. 2. All low carbon steels around 85000psi, Water quenched around 280000 psi, Oil quench around 270000psi, and air quench also 270000psi 3. This is because the more carbon in the structures results in a higher hardness. 4. This is due to the specimens heated at 960C being austenite and the specimens at 500 C being cementite. 5. Normalizing forms a uniform layer of austenite by heating at 60C then removes it. This improves ductility. Full annealing converts to homogeneous austenite, this provides the weakest mechanical properties. Process annealing induces ferrite to form, this reduces hardness and internal stress. 6. Yes, this statement is true, the composition and heat treatment are main factors. 7. This appears to be pearlite, and because of the cooling process required to chaiv perlite, i don't believe this is possible. 8. Yes the comparison would be valid as they are measuring the same value, similar if one is to convert F to C. 9. Pearlite has a DPH of 200 kg/mm^2 (Britannica) 10. Yes, cementite is harder than pearlite. The extra carbon in the cementite structure makes it harder 11. Annealing, quenching, tempering 12. A case hardening processes only hardens the outside of the metal, this is done so the interactable surface retains its nee properties, but the inside can absorb shock 13. Tempering returns ductility and fracture resistance to the sample in question Appendix A. Karl-Erik Thelning. (2000). Steel and its heat treatment (2nd ed.). Butterworths. 10