Was in the process of drifting a slit for my first hammer eye punch in a rectangular piece of 4140 about an 1 1/4 deep and 3/4 of the way one of the corners chipped off (about 1/4" of a 1").  I was cooling in my water quench bucket after every second/third hit, I didn't work the material cold (good orange heat), used a 2/5lb hammer.

What did I do wrong? I should be able to salvage the chisel by regrinding and re-heat treating, I just don't want to repeat my mistake.

Any advice (pertinent to my slitting chisel) is welcomed.

Edit: Should also indicate that the 4140 billet was annealed in vermiculite for a couple hours after I pressed it from round into rectangle.

Some picture would help..   Your information is a little to vague for me.. But the only thing I can come up with is it must  of gotten to hot when made and had an internal crack or it was at to high a temperature when you did your dunk to cool it off after using it.. 

The way your chisel cracked out is typical for the design of a narrow kerf cold chisel..  Hot chisels will usually normalize themselves in use so even if left a little hard they soften pretty quickly.. 

Sorry I couldn't be more help but without pictures to see how the failure took place it's kind of tough.. 

were you slitting a hole or drifting a hole?? A drift is something you drive through a piece of metal to get to the final shape, a punch is what you use to actually create the hole. I take it out every hit, it cools itself. when it gets stuck, I cool the punch off in a can of beeswax and graphite mix that cools it slower than water, and lubricates the punch tip. Also when removing it ever hit you don't run the risk of cooling it when it is above critical temperature and hardening it, which sounds like that may have happened. I don't recommend you "re heat treating it" as it is a waist of time. Like Jlpservicesinc said, they will normalize themselves in use, and you loose their temper the first use.

Also, no reason to anneal the 4140 before it is being forged, afterwards though could be of benefit if you were to be doing any grinding or filing. Basically, anything you do before critical temperature is lost once you go above it when we're talking about heat treating.

Not so much about the issue you are having right now, but I recommend using a punch rather than slitting a hole when making any hole in steel, and especially when I want it to be able to hold up to some hits. with a slitter, you don't punch a plug out, but just create a bubble that you then pop when you back punch creating cold shuts inside the eye, weakening the eye. Using a punch, you get a nice clean hole, no "rag" and a stronger eye in this case. Look up the "Brian Brazeal Punch" to get an Idea of a punch that works well for hammer making, its what I and lots of others use and enjoy, works great. I can post some pics if you would like, I have found it hard to find a good pic of the actual tip of the punch and the grind of it.

                                                                                                                                Littleblacksmith

What alloy is the chisel?  The high alloy tooling does NOT like being dipped in water to cool. You cool it in air.

Thanks for all the replies.

jlpservicesinc - I don't have any pics and have to dig out the chisel after work to get some (this happened at a hammer in and I haven't unpacked yet this week).

littleblacksmith - Originally I was worried about slitting the 4140 as it was relatively thick so I was going to drill some 5/16" holes then slit the webs (thus the annealing). Well I got impatient with the lineup on the mill drill at our hammer in and decided I could just use the slitting chisel. I'll be sure to invest in a better coolant/lube, where did you buy your powdered graphite? Also its somewhat ironic that the piece I was slitting was for a Brian Brazeal Hammer Eye Punch. I'm just starting out and am in the process of forging most of my tools.

ThomasPowers - Not sure what the alloy is, it wasn't supplied by CentaurForge when I bought it from them. It's clearly marked Peddinghaus made in Germany. Given the sound it made when it broke (a sharp "Ting" when I quenched it) I'm pretty sure you're right about it being a high carbon tool steel.

For graphite powder, look for the John Deere 1lb (or larger) container. Best price on graphite I've found - about $5-6 a pound.

http://www.greenpartstore.com/John-Deere-Powdered-Graphite-TY26253.html

Don't know where you're located (might add that to your profile info), but you may have a John Deere dealer near you to get it from directly.

+1 on the JD graphite. 

Also, if you're looking for a cheap/free source of beeswax as an ingredient in punch lube (as well as for a myriad of other uses), make friends with your local Eastern Orthodox priest. Orthodox churches go through a lot of beeswax tapers, and somebody has to do something with the stubs. 

6 hours ago, Chrislmathie said:

Originally I was worried about slitting the 4140 as it was relatively thick so I was going to drill some 5/16" holes then slit the webs (thus the annealing). Well I got impatient with the lineup on the mill drill at our hammer in and decided I could just use the slitting chisel. I'll be sure to invest in a better coolant/lube, where did you buy your powdered graphite? Also its somewhat ironic that the piece I was slitting was for a Brian Brazeal Hammer Eye Punch. I'm just starting out and am in the process of forging most of my tools.

ThomasPowers - Not sure what the alloy is, it wasn't supplied by CentaurForge when I bought it from them. It's clearly marked Peddinghaus made in Germany. Given the sound it made when it broke (a sharp "Ting" when I quenched it) I'm pretty sure you're right about it being a high carbon tool steel.

Aaaahhhh the evolution of tool making! love it, I enjoyed that a lot! You can make a hand held v tipped punch to punch it if you'd like, or if you really want to get fancy you can weld on a handle so you don't roast your hand.

got it. I forge just about all my hand tools, obviously not my anvil, and not all my hammers, though about 4 of them I made and still making more. And the ones I did buy were bought with money I made selling stuff that I made.

I get my graphite from the link that John in Oly, WA mentioned.

Here is a link to the thread I started on the evolution of tool making. Starting with just a hammer and hot cut and making all the tools to make the hammer and hot cut!

                                                                                                                         Littleblacksmith

Tho this is an older thread, lots of good ideas here... Thanks to all for posting

Dave

On 5/17/2017 at 4:38 PM, Chrislmathie said:

I was cooling in my water quench bucket after every second/third hit, I didn't work the material cold (good orange heat), used a 2/5lb hammer

I know this is an old thread but this may benefit someone reading this in the future. If it's the same type of Peddinghaus slitting chisel I have it's made from a manganese silicon steel and is  an air cool only alloy. 

Pnut