154cm HT Question

sunny_2_75

sunny_2_75

Joined
Nov 23, 2009
Messages
71
Well I have a couple things....first, I just received my 10 in KMG 2HP Variable speed Grinder:D enough said!! Now my question. I have some 154cm I bought awhile back. I didnt like how the HT went as the blades just didnt hold an edge as well as I thought they would. I wrapped them in SS foil, placed them in the oven and full ramped to 1400 and equalized. Then to 1950 and held for 30min. I plate quenched, dry iced for 1hr and tempered twice at 400 for 2hrs each. I dont have a hardness tester but they didnt perform as well as I thought they would. Blades were ground to .015. So I did some research. It looks like an oil quech is better than a plate quench....? If so, it mentioned that you oil quench to 1000 f. then air cool. My question is how do you know when you get to 1000f? Is it critical to be at 1000f? can you gage it with the amount of time its been in the oil....lets say 3 sec or so? Im wanting about 60hrc on the blades im making. Any advice would be appreciated. Thanks Sunny
 
With that H/T you should be getting about 58-59.Try finding a machine shop with a tester close to you.Or if you want H/T a 1" square coupon,grind it clean to 400 grit on both sides.Mail it to me and I will test it for you.Send me a PM or e-mail.
My H/T I ramp to 1200 hold 15 min,ramp to 1600 hold for 15 min,ramp to 1950 hold for 40 min,plate quench,cryyo overnight,two tempers at 425 and get constat 60-61.
Personally I would not mess wwith trying to oil quench 154cm.
OHH,and congrats on the KMG you will grow to love it.:D


Stan
 
Remember that dry ice [sub-zero treatment] is -100F and cryo , liquid nitrogen [cryo] is -300 F .Cryo should get 1-2 HRC points higher than dry ice.
 
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mete is right,before I started doing cryo,my 154 would be in the 58-59 Rc range.Also H/T can vary alittle from batch to batch of the same steel.I try to buy 5-7 bars at a time to help with that.
 
Thanks for the feedback guys!!!sorry I havnt gotten back. I appreciate any help I can and always seem to get it here. Sbuzek, I might just take you up on that. By the way, It seem rediculous to me not to have a hardness tester. I have looked around and....dang!!!...they are expensive! Anyone know of a model/manufacturer that has an Rockwell C hardness tester thats reasonable?
 
sunny_2_75 said:
Short answer, no.

Long answer, no but if you are consistently looking locally on Craig's List and eBay you may get lucky and find a somewhat reasonably priced one. I bought one from a local seller on eBay who was closing his industrial shop. Got it for $400.
Click to expand...
 
There are the major elements and there are minor elements. The minor ones have little effect on HT or properties.. When I use the terms major and minor that does not mean amounts only but are they there for an important reason . A full analysis has everything even those that are not put there or even if they're not good for the steel. All the elements have a range .]1.2 - 1.6 % for example, not just an exact amount .
 
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