Work-hardening of 440C?

AlphalphaPB · Jul 29, 2003

Hi, I'm working on my first knife. I haven't gotten a belt grinder yet, so to profile I'm using a combination of a drill press, hacksaw, Dremel cutoff wheel, and files.

I didn't research hacksaw blades as much as I should have, and didn't get one with enough teeth per inch. As a result, the teeth got a little screwy and dull, heating up the tip of the 440C blade to a point where it was too hot to touch.

After getting the tip area to shape with the hacksaw, I moved in with the file, and quickly noticed an area where the file was slipping. The file wasn't cutting, and in fact, the blade cut some nasty grooves into the file.

This is all academic now, since I just took care of the spot by grinding it off with a sanding ring on the Dremel, but did this happen because I heated the blade up too much and work-hardened it? What kind of temperature is required to do this to 440C?

Thanks in advance for your replies. I really enjoy learning here.

mete · Jul 29, 2003

You don't have to heat it to work harden that's why it's also called cold working. I have no experience in work hardening of the 400 series though that is obviously what you did. However I am very familiar with the 300 series .The least affected by work hardening is 305 and the most affected ,by far, is 301. In fact we used to make springs of 301 by cold rolling. Another alloy notorious for that is monel metal as I remember. To drill such alloys you better have a drill with the perfect angle ,very sharp and the perfect speed and feed otherwise the metal work hardens in front of the drill and you're stopped right there. For you the poor choice of saw blade worked instead of cut the steel, the blade then created heat from friction.

Jason Arnold · Jul 29, 2003

AlphalphaPB,

Unless you saw the steel get a little red for a minute, I am doubtful you got the steel hot enough with those methods to get that effect you are experiencing. Like mete, said, you may have work hardened it. But that effect should have began when the file started to go dull and the file was no longer really removing metal, but rather "burnishing", in effect. Is the file dull? (Dull may also, simply be the problem). Also, I cannot see a work hardened 440C as being harder than a file, to cut it. However, in some cases I have use dull/semi-dull files on sharp corners though and had lines cut into the file, but not on a fresh, sharp file unless you press real hard and smash the teeth.

Dan Gray · Jul 29, 2003

you may have hit a hard spot with the hacksaw in the 440C
causing it to dull I don't think you worked it enouph to work
harden it.

just me 2 cent

heatride · Jul 29, 2003

AlphalphaPB all I use is 440C and never had this happen(EVER).I think Jason and Dan are on to something. I bet its not the steel like they said , bet its the files and hacksaw blades.

rlinger · Jul 29, 2003

mete,

What in the analysies actually causes work hardening to occur and why. Is it partially caused by local compression? Thanks.

RL

heatride · Jul 29, 2003

Here Roger this link might give the information I think your looking for.

Work Hardening

Jason Arnold · Jul 30, 2003

Work hardening occurs due to the deformation of grains. This rlinger, can come from compression, pulling, twisting, etc. Stretching and distorting grains (cold) creates stress, which leads to hardness, which leads to increased strength (as well as brittleness and loss in ductility for that matter).