Jominy End-Quench Test.
In this lab, we will perform a Jominy Test on a sample of 1018 Steel, which contains 0.18 wt % C.
Our first step is to austenitize our sample, meaning that we heat it up to a temperature where the sample transforms from the BCC α-Fe to the FCC γFe, also called austenite. For our sample, we’ll use a temperature of 1700 °F (about 927 °C), holding it at temperaure for 30 minutes. Notice where the sample would be on the Fe-Fe3C phase diagram, shown below, when it is held at 1700 °F.
Shackelford’s Figure 9.19, page 272. The Fe-Fe3C phase diagram.
The sample is quickly removed from the furnace and placed in the Jominy tester (see Figure 10.21), and the water cooling begins. Notice that only one end of the sample is directly cooled by the water flowing in the Jominy test apparatus. This means the highest quench rate occurs at that end and decreases as we move away from the quenched end. You may be able to demonstrate the validity of this last statement by something you may observe during the test.
When the sample reaches room temperature, we may safely remove it for further testing.
Shackelford’s Figure 10.21, page 325. The Jominy End-Quench test.
Measure the Rockwell hardness at various distances from the quenched end, every 1/16 inch up to one-inch, then every 1/8 inch up to twoinches. Present your data in a graph like Figure 10.24 shown below.
Shackelford’s Figure 10.24, page 326. Hardenability for various grades of steel. These grades all contain 0.40 wt % C.
Some questions you may wish to ponder as you write your report.
• Is there a standard size for Jominy samples?
• How does the Jominy apparatus actually work? Note that our apparatus was designed and constructed by one of our students.
• Did you observe anything during the Jominy Test that confirms the idea that the quenching rate is lower away from the quenched end?
• How does your data for 1018 steel compare to the other grades of steel shown in Figure 10.24?
• Can you find for Jominy data for 1018 steel? How does it compare to our data?
• What is ideal hardenability behavior?
• How do the curves we have seen, both in the lab and in our textbook, compare to this ideal?
• What can you conclude about the effect of quenching rate on hardness?
SRT 4/20/2020
