1095/W2 Heat Treat Confusion

[ScarFoot]

So I went through my scrap bin a few weeks ago and decided to give a few old blanks another chance. They were all 1095 and W2 with an odd 1075 thrown in. I heat treated them all again and tried a few different things this time. A few of these blanks failed 2 previous hardening attempts miserably. The failed heat treat protocol for the 1095/W2 blanks was to soak at 1465F for 15 minutes and quench in ambient Parks 50. Out of the quench into a 300F snap temper, Then a 2x2 tempering cycle at 405F which was giving me 60-61 HRc on my test pieces.

The protocol I ran the other night was to soak at 1435F for 15 minutes then quench in oil or brine, both at ambient temp. The oil was about 2 gallons of Parks 50, the brine was 5 gallons of water with about 3.5 pounds of salt. I kept adding salt until it stopped dissolving easily. After quench they were snap tempered at 300F and then 2x2 tempering cycles at 405. After tempering, the brine quenched 1095 and W2 blanks are 64 HRC. I did check against a cal block and checked 3 locations per blank. The other water quenched 1095 blank tested out at 62HRC but is much thicker than the other two (0.125” vs 0.073”) so I wasn’t surprised it was a bit softer.

Anyway, I was expecting them all to be around 60 HRC. I can understand them being slightly higher but, 64 HRC after 2 tempering cycles seems a bit odd. All were surface ground prior to testing in all cases and in all cases they were all tempered together. I’m not sure if it was the brine quench or the lower soak temp or both that made the difference but something clearly worked this time that didn’t the last two times. I’ll just have to temper them down a bit.

The 1075 came out right where the knife engineering book said it would.

I don’t really know what to take away from this but at least I got a few data points to play with.

 

[Thescrawnylumberjack]

I’ve done some 1095 in a brine of something like 20% salt be weight since that’s about the max that can be dissolved into water if I remember correctly. I don’t remember the protocol but I do know I got 64 hrc after two temper cycles. It had a pretty bad warp in it as well from that quench. I know with parks 50 I can achieve 63-64 as well. Both of these tests pieces didn’t utilize a DET anneal prior to HT.

 

[Stacy E. Apelt - Bladesmith]

More salt does not increase the hardening ability of brine. The optional concentration is around 10%. However, it probably doesn't affect it much or any if it is a bit higher. 10% works out to be .75 pounds per gallon or around 1.5.cup per gallon. 3 pounds (6 cups) of rock salt in 4 gallons of water is my brine mix. Pretty much any type of salt or ice-melt will work.

Salt gets the highest hardness results with hyper-eutectoid steels. W2 with low manganese is the best choice.

If you can live with the dreaded PING happening occasionally, brine is a fun thing to play with. Otherwise, Park's #50 is a wiser choice.

405°F is not going to lower the hardness on a brine quenched 1095/W2 blade to the same point as a Park's quenched blade because the "as-quenched" hardness will be higher with brine. Thickness also greatly affects quench hardness (for several reasons).

 

[ScarFoot]

More salt does not increase the hardening ability of brine. The optional concentration is around 10%. However, it probably doesn't affect it much or any if it is a bit higher. 10% works out to be .75 pounds per gallon or around 1.5.cup per gallon. 3 pounds (6 cups) of rock salt in 4 gallons of water is my brine mix. Pretty much any type of salt or ice-melt will work.

Salt gets the highest hardness results with hyper-eutectoid steels. W2 with low manganese is the best choice.

If you can live with the dreaded PING happening occasionally, brine is a fun thing to play with. Otherwise, Park's #50 is a wiser choice.

405°F is not going to lower the hardness on a brine quenched 1095/W2 blade to the same point as a Park's quenched blade because the "as-quenched" hardness will be higher with brine. Thickness also greatly affects quench hardness (for several reasons).

I was shooting for 10%. I dissolved most of a 4 pound box of rock salt into a 5 gallon bucket of water. It was the first time I’d used brine. I was mainly using it because I knew some of those blanks didn’t harden previously in Parks 50. I enjoyed watching the scale blow off of the blanks. The end of the handle broke off of one. Two others had small cracks I’m going to try to grind out. I broke one in half trying to straighten it. Since they were all old blanks I wasn’t terribly concerned about failures.

The only data point I had was W2, water quenched from the Knife Engineering book. I was expecting the hardness to be closer to it. I should have done a little more research on expected hardness from brine quenching. No big deal though. I’d rather them be too hard than too soft. That’s an easy enough fix.

 

[Stacy E. Apelt - Bladesmith]

If you have cracks you can see you likely can't remove them. There are deeper and longer cracks you can't see. If they are just for you and the shop, go ahead and try.
When doing a water/brine quench, don't evcen stare hard at te blade before full tempering. Then check for hardness before trying any bend straightening. A water/brine quench leaves the blade VERY brittle.

 

[ScarFoot]

If you have cracks you can see you likely can't remove them. There are deeper and longer cracks you can't see. If they are just for you and the shop, go ahead and try.
When doing a water/brine quench, don't evcen stare hard at te blade before full tempering. Then check for hardness before trying any bend straightening. A water/brine quench leaves the blade VERY brittle.

The brine quenched ones are all pretty much practice blades. I took them to the toaster at a dead run to get them into a snap temper until the good oven was ready. One of the ones that cracked was oil quenched and it cracked towards the tip but I think it might have happened while I straightened it. It had a pretty noticeable warp in that same area. I didn’t notice the crack until I got to 400 grit. It’s a big blank so I might be able to reprofile the tip completely and take it out.

I’m surprised the oil quenched blades were a bit harder too. I’m assuming the lower soak temp allowed them to quench faster?.?.

 

[Daniel Fairly Knives]

The last time I bought 1095 I messed with the heat treat for days and then ht'd about 50 kwaikens in a row to get them nailed just right. I like to test and also etch to see visible results.

It is not a bad idea to do a few stress relief and normalizing cycles for a lot of reasons... you might see more consistent results and a point where the right amount will make it "easy" to hit the RC you need.

Edge thickness is really important as well as an even grind.

 

[ScarFoot]

The last time I bought 1095 I messed with the heat treat for days and then ht'd about 50 kwaikens in a row to get them nailed just right. I like to test and also etch to see visible results.

It is not a bad idea to do a few stress relief and normalizing cycles for a lot of reasons... you might see more consistent results and a point where the right amount will make it "easy" to hit the RC you need.

Edge thickness is really important as well as an even grind.

My grinds were good and even but a few were definitely too thin at the edge. I’ve put a lot more focus on good even grinds before heat treat over the last 6-8 months and it definitely makes a huge difference. I get them to the point they’re essentially ready to hand sand and finish before heat treat now. After the first edge waffled and cracked on me the other night I ground the edges back on any of the rest that were thin before heat treat.

I generally do test pieces of any new steels I use and keep them in envelopes with the heat treat protocol and hardness results written on them. I always line that out before heat treating the blades.

I don’t mess with 1095 much anymore. These were just some old blanks I’d messed up too bad to fix at the time. I always go through my scrap bin once or twice a year to see if I’ve gotten good enough to fix the mistakes that were over my head when I initially made them. I do still tinker with W2 from time to time but I mainly use 80CrV2 now. I think I might try some “exotic” steels this year but I’m not in a big hurry to.