My tempering logic: sensible or hocus pocus?

P.Brewster

P.Brewster

Joined
Jul 25, 2007
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1,380
Last week, I did some stars out of 1075 and spikes from W1. Neither have an edge, so my demands are not as critical as those who are making cutlery.

Long story short, I normally temper everything twice; 2 hr in a PID-controlled toaster oven.

For some reason, I seemed to think that it would be ok to temper the 1075 only once (because the items had to ship the next day)... but I felt that the W1 really needed that second temper.

Is there any validity to this thinking?

thanks
 
Did you temper at a hotter temperature than the first temper? If not then I don't think there was any need for the second temper when working with 1075 or W1, but it can't hurt. I would be interested to see if there is any facts backing up the benefits of a second temper on carbon steel.
 
Aiming for the low 50s, I normally temper the W1 at 670°, and the 1075 at 600° (and I do play around with those temps a bit)... I didn't do anything differently with my temps. I just did one temper for the 1075, and two for the W1.
 
The first temper not only stress relieves, but also converts retained austenite (RA) into martensite. The second temper stress relieves the newly converted martensite.

The question is how much RA is really in W1 or 1075 following quench, and how much of that can be converted to martensite during the first temper. The answers there are beyond me as I don't work with either steel, but I do know that more complex steels such as O1 benefit from that second temper.

--nathan
 
Word is that very simple carbon steels only require one temper, I always temper twice. W1 should have basically the same requirements for time at temp that 1075 does, so your logic was flawed :D
 
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