Water Hardening Q

For W1 tool steel:

Preheat to 1200 F then heat to 1425 F and hold 5 minutes per inch of cross section. Quench in a water 10% brine solution. Temper at 350 F for two hours. From "Heat Treatment,selection and application of tool steels" by Bill Bryson.

Karl

this should help, but be specific about what type of steel and you will get a more specific answer.

wrong link, try this one

Your steel should have come with directions on heat treating, sometimes it's a separate sheet, sometimes it's on the VPI wrapper. If you didn't get clear directions with the stuff, you got rooked, don't buy stock from that supplier again. Brownell's has some directions in their catalog and on their website for both their oil-hardening and water-hardening stock, you might try those directions. For hardening, heat it up until a magnet is no longer attracted, then quench. The second part of heat-treating after the hardening part is called tempering, not annealing. For cutting tools, you can temper in a toaster oven with good results, the temperatures needed are that low. No quench needed afterwards and follow the heat treating instructions for tempering times for best results. Harden and temper before grinding the final edge on the parts, thin edges will burn.

Stan

FWIW, I've never had any trouble with just heat, quench, temper. Maybe a minute at temp.

I'd guess the difference is more changes to the hot phase, thus allowing more complete hardening? Ed?

Tim

-- "That's for the courts to decide." - Homer Simpson Website @

I suspect it's W-1, but when MSC sent it to me, it wasn't listed on the packing sheet nor was the steel itself marked in any way.

By way of follow up. I began the hardening process for the first piece today. I held the piece at red color for 1 minute and then quenched it in water. A file skates over the surface, so it's hard. I dug up some old Home Shop Machinist magazines from 10 years ago that had information on hardening and tempering. Based on this and some other reading this morning I thought I'd continue in an old fashion using oxidation colors rather than a specific annealing temp and time. I thought I'd play a flame over the side farthest from the cutting edge and let the oxidation color migrate toward the cutting edge. When the cutting edge is light yellow, I'll quench in water again.

This is the first time I've ever hardened anything. So far so good. If this doesn't work, I'll repeat the hardening process and try annealing it with an oven.

RWL

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I don't remember what the physical change is supposed to be. However, long tempering times significantly increase toughness without reducing hardness. There are some graphs that show the specifics of it in _Tool Steel Simplified_.

Ed Huntress

I think you still really need to do a full temper to create a more durable cutting tool, and then follow by a selective temper as you described, or you risk a brittle steel that isn't entirely tempered through it's cross section.

It's tempering, or drawing the temper ..... annealing is a different process all together

To anneal decent steel, I heat it to white hot then cover it with sand and leave it overnight. The sand holds in the heat so it will cool slowly. Not all steel will stand being heated to white hot, if there is too much carbon it will start sparking on the edges before that point; in that case you stop when it begins sparking.

To harden a blade, I heat it to cherry, let it cool to bright orange, then quench it in used motor oil. The steel will absorb minute amounts of carbon from the old motor oil, so if your steel is a bit on the "mild" side use really dirty motor oil. There are cases where you actually want to "water harden" which in my terminology is a different technique, where you run cold water over one part of a blade (usually the back which has been tempered for strength/spring) while you heat the edge to cherry before quenching.

Everybody has his own ways of doing this stuff. Some do it "scientifically". I've found that different pieces of steel have different characteristics, sometimes subtly different based on which lot it came from.

I was told once, which may be apochryphal, that the spaniards in the middle ages who were making the best damascus swords used a slave to temper their blades, plunging it down their throats and through their hearts; go figure, the guy who told me this story knew more about making things from steel than anyone I've met before or since. It sounds brutal but this was about the time of the inquisition and their civil rights left something to be desired.