Lab 3 has two tests in which the procedure and the objectives are different. The first test is known as the Heat Treatment Test. In this test 6 sample bolts are placed in a heated furnace. The sample bolts are the cooled by a method called quenching. This method is used to shock cool the sample bolts by immerging them in liquid or gas. The shock cooling of the samples increase the hardness of its structure. The objective of this test is to determine the hardness of the sample bolts after the quenching. The second test is known as the Spark Test. In this test 4 specimens are worn down on a grinding machine. The type of metal that the specimen is made of can be determined by the patterns of the sparks. There are 10 different patterns of sparks. Both of these tests have two different procedures and objectives; but the one thing they have in common is heat. Heat is used to induce the hardness of the sample bolts and generates sparks used to determine the type of material the specimens are.

1. The furnace and tongs were preheated to avoid thermal shock.
2. The six samples (bolts) were placed in the furnace until red-hot (orange).
3. Each sample was cooled in a different manner;

• In cold water
• In brine (salt water)
• At ambient temp (air cooled)
• In oil
• Cooled in the furnace
• Using Jominy end quench

1. A metal sink was filled with cold water.
2. The sample was removed from the furnace with the tongs and held in the cold water for approximately 10 seconds.
3. The sample was then dropped into the sink to cool further.

1. Salt and water were mixed in a metal container.
2. The metal container was placed in a water bath (in a metal sink filled with cold water).
3. The sample was removed from the furnace with the heated tongs and held in the brine for approximately one minute.
4. The sample was then dropped into the brine to cool to an adequate handling temperature.

1. The sample was removed from the furnace with the heated tongs and placed on a heat resistant tile on the floor to cool to ambient temperature.

1. A metal container with oil was placed in a double water bath system; which comprised of a metal container containing cold water in a cold-water-filled metal sink.
2. The sample was removed from the furnace with the heated tongs and held in the oil for a few minutes.
3. The sample was then dropped into the oil to cool to handling temperature.
4. Excess oil was wiped from the surface of the sample, in preparation for the hardness test.

1. The furnace was turned off.
2. One sample was left too cool in the furnace.

1. A water jet system, which sprayed water upwards, was set up inside of a metal sink.
2. The sample was removed from the furnace using tongs and positioned above the water jet system.
3. The water jet was started and sprayed onto the bottom of the specimen until the specimen was coo

1. One side of the head of the bolt was gently filed with a metal file to remove the buildup of iron oxide.
2. The same area was then gently sanded, using 600 sandpaper, to achieve a polished surface.

1. The machine is turned on.
2. The penetrator (1/16" ball) is selected.
3. The test force (100 kgf) and adjust knob is selected.
4. The penetrator is inserted carefully guarding the tip.
5. The penetrator is tightened.
6. The work piece is placed squarely on the platform.
7. The platform is gently raised near the penetrator.
8. The contact is initiated between the piece and the penetrator, by gently raising the platform until the squares on the left side of the monitor reach the "set" square, release the platform knob and wait for the reading to appear.
9. The screen displays the final results of the test. In this case the final reading of the metals hardness is 86.6 HRB.
10. The platform has to be released; press clear and press reset, repeat the steps until you have completed 5 trials for each piece that needs to be tested.

Jominy

1. 68.7 HRB 1- 59.6 HRB
2. 50.7 HRB 2- 63.6 HRB
3. 50.9 HRB 3- 67.2 HRB
4. 53.6 HRB 4- 59.6 HRB
5. 51.0 HRB 5- 58.2 HRB

The spark test was conducted by testing four (4) separate specimens and analyzing their sparks to determine their metallic composition. The specimens that were used were a profiler, a milling bit, a file, and a hacksaw blade. To perform the tests, first, the grinding machine was turned on. With the proper eyewear in tact, the human subject commenced the test by applying pressure to the spinning grinder wheel with the metallic specimen. When enough friction was generated, the result was a marvelous array of flares known as sparks. Each specimen generated a different type of spark hence giving insight to its metallic composition. The results of the tests were as follows: The profiler-.

The milling bit-.

The file- and

the hacksaw blade-.

Comparing these results with the "characteristics of sparks key-guide", it was determined that the profiler produced sparks consistent with low-carbon and cast steel. The milling bit produced sparks consistent with wrought iron. The file produced sparks consistent with high-carbon steel, and the hacksaw blade produced sparks consistent with monel and nickel.

After the trials were conducted, the human subject safely turned off the grinding machine and removed his safety glasses hence concluding the spark test.

The property of hardness was measured and evaluated before and after the heat treatment of five similar specimens of an iron alloy. The specimens were quenched using various mediums and the results tabulated in the Analysis section. For the first three specimens, quenched by water, brine, and oil, the time allotted for the cooling process was constant but the rate of quenching altered according to the method of quench. The hardness value varied considerably from specimen to specimen. The water-cooled specimen generated the largest value for hardness, followed by brine-cooled and last by the oil-cooled.

The remaining two specimens required a significantly longer amount of time to cool. For the air-cooled and furnace-cooled specimens, the length of time was the relevant factor in the severity of quenching. Instead of being quenched by a liquid medium, the remaining specimens were subject to different reductions in temperature. The difference in temperature inside and outside the furnace contributed to the differences in the hardness values measured for each specimen. The air-cooled specimen generated a greater value of hardness than that of the furnace-cooled specimen. The air-cooled specimen was exposed to a lower temperature medium that increased the rate of cooling for the specimen. In result, the higher severity rate increased the hardness property for this particular specimen.

The following section of the experiment analyzed the different values of hardness affected by end quenching. An additional specimen was evaluated after being slowly quenched by water in sections from one end to another. The specimen was tested for hardness in five separate one-centimeter increments from the tail of the specimen to the head. As the test proceeded from the tail to the head, the values of hardness decreased from highest to lowest respectively. This experiment proved the assumption that the hardness value would be the highest nearest the tail where the quenching originated. This portion of the specimen cooled at a higher rate because the heated alloy was instantly subjected to quenching at its highest temperature level. The remaining sections of the specimen cooled with respect to a reduced temperature level.

The aim of this lab was twofold. One, to learn the effect that different types of quench has on a metal and two, to get a general idea of the content of different metals by the sparks these metals give off when pressed against a grinder.

This lab utilized the use of the Rockwell hardness tester, which was learnt in a hardness-testing lab and introduced the proper handling of hot metals, thermal shock and lab safety.

The quenching process proved that different quenching media have a different effect on the hardness of the metal, brine quenched giving the hardest and furnace cooled the least hard.

While the Jominy end quench test gave a greater hardness at the end closest to the water, the other values, though lower in value, were too variable to be conclusive.

This lab was instrumental in providing a practical representation of the theory of course. Time management and teamwork was also very important aspect of this lab. One example of this was Team Kenya’s decision to share all digital photos with the members of other teams.

Kalpakjian, Serope and Schmid, Steven R. "Manufacturing Engineering andTechnology."

New Jersey: Prentice-Hall Inc., 2001.

Li, J C M. "Microstructure and Properties of Materials".

http://www.wspc.com/books/materialsci/4311.html