OK, I'll confess. I don't make knives. But I have a few Kershaws that I love and EDC. 
By way of introduction, I'll just say that I am a student and I am here because I have some heat treat questions that I hope somebody can point me in the right direction...
I am currently taking a materials technology class. For a lab, we were given 5 steel specimens of various shapes: 1” round, 1” hex, ¾” hex, 1” square, and 13/16” square. Each sample was about 1/3” thick. We were told that each shape corresponds to one of the following steels: 1018, 1045, 4140, 1215, and 8620.
For the lab we were supposed to test the hardness, then heat treat them, then test the hardness again. Finally, we are supposed to match each shape to the appropriate steel type.
The heat treat process consisted of being inside the heat treat furnace at 780°C for 20 minutes followed by an immediate quench in room temperature oil.
For hardness, here is what we measured. The first number is pre-heat treat. The second number is post heat treat.
1” round – 93 HRB then 87 HRB (marginally softer)
1” hex – 26 HRC then 35 HRC (harder)
¾” hex – 93 HRB then 76 HRB (much softer)
1” square – 17 HRC then 51 HRC (much harder)
13/16” square – 88 HRB to 44 HRC (much harder)
I am having difficulties matching up the results for each steel type. Here is what I have concluded so far:
1” square – 4140
13/16” square – 1045
1” round – 1018? (Didn’t respond much at all to heat treat process.)
After that, I am stuck. I have done a bit of research but can’t figure out how the 1215 and 8620 would respond to the heat treat process we put them through. The instructor won’t tell us the condition of the samples when we received them so we don’t know if they were hot rolled, cold-worked, annealed, cased hardened, etc. All he said was to look up how they are normally purchased and that might give us some ideas.
I know 8620 is commonly used in case hardening applications. I’m wondering if this sample would be the one that became much softer after our heat treat process?
Any suggestions would be helpful!
By way of introduction, I'll just say that I am a student and I am here because I have some heat treat questions that I hope somebody can point me in the right direction...
I am currently taking a materials technology class. For a lab, we were given 5 steel specimens of various shapes: 1” round, 1” hex, ¾” hex, 1” square, and 13/16” square. Each sample was about 1/3” thick. We were told that each shape corresponds to one of the following steels: 1018, 1045, 4140, 1215, and 8620.
For the lab we were supposed to test the hardness, then heat treat them, then test the hardness again. Finally, we are supposed to match each shape to the appropriate steel type.
The heat treat process consisted of being inside the heat treat furnace at 780°C for 20 minutes followed by an immediate quench in room temperature oil.
For hardness, here is what we measured. The first number is pre-heat treat. The second number is post heat treat.
1” round – 93 HRB then 87 HRB (marginally softer)
1” hex – 26 HRC then 35 HRC (harder)
¾” hex – 93 HRB then 76 HRB (much softer)
1” square – 17 HRC then 51 HRC (much harder)
13/16” square – 88 HRB to 44 HRC (much harder)
I am having difficulties matching up the results for each steel type. Here is what I have concluded so far:
1” square – 4140
13/16” square – 1045
1” round – 1018? (Didn’t respond much at all to heat treat process.)
After that, I am stuck. I have done a bit of research but can’t figure out how the 1215 and 8620 would respond to the heat treat process we put them through. The instructor won’t tell us the condition of the samples when we received them so we don’t know if they were hot rolled, cold-worked, annealed, cased hardened, etc. All he said was to look up how they are normally purchased and that might give us some ideas.
I know 8620 is commonly used in case hardening applications. I’m wondering if this sample would be the one that became much softer after our heat treat process?
Any suggestions would be helpful!