Ht 5160 ?

Gahagan

Well-Known Member
Ok I need to know the temps to HT 5160. What is the soak temp and what for tempering and how long for each?
 
1525 soak for 10 minutes to harden

temper 375 for 2 hours twice.

That'll make you a fine knife. I give it a soft back draw after tempering. Also done twice.

-Josh
 
5160 is a hypoeutictic steel that's not going to form any appriciable amount of carbides other than cementite so I don't think that it really needs 10 minutes soaking at themperature in other than a kiln. I would cut it back to about 2 minutes if I were using a gas forge Just look for the decalesence and hold until heated through then quench to harden.

Doug
 
Actually Doug it is somewhat the inverse. At .55% to .6% Carbon at best there will be no cementite, but there could be chromium carbides, and with that carbon level if there are chromium carbides they will be at the expense of proper austenite solution. So while it is generally not always a good idea to attempt a soak in a forge if you do not have good controls, but if one has an oven or those controls, a soak is almost always beneficial for total solution.
 
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I have just been gifted some 6150 and am lead to believe that heat treat is the same as for 5160. Does that sound right?
 
Thanks for the clarification, Kevin. I guess that my understanding that with a steel like 5160 that the carbon is taken up by the formation of cementite in the pearlite structure, leaving little to no carbon to form any carbides outside of the pearlite was wrong. I guess it's another of those "rules" that we find that is highly dependent upon the alloy, and the equipment, being used.
 
Doug, I think you and Kevin are talking about 2 different points during heat treatment. There won't be any cementite outside the pearlite, just as you describe, but when austenizing, there won't be any pearlite either, or we hope not. In any case, there will be more ferrite, which has essentially zero carbon in it for our purposes. For that reason, a soak would be good to get the carbon evenly distributed.
 
The point is that there would not be much carbon tied up in carbides other than cementite within the pearlite that will need to be soaked to be put into solution in the ausinite, unlike something like 52100 which will have plenty of proeuticiod carbides to dissolve to release their carbon. The general information that I had learned, maybe by mistake, is that a hypoeutectic steel can be soaked a little hotter for a shorter period of time. As Kevin has pointed out in other threads, soak time will not lead to a problem with grain growth if the temperature is kept down. Also, kilns tend to heat steel more slowly than a forge, at least from what I've read.

Doug
 
My interpretation is that there aren't as many carbides to dissolve, just as you describe, but the distance between the carbides will be greater. Thus, even for a hypoeutectoid steel like 5160, a little soaking will ensure the carbon is evenly distributed in the larger spaces between the carbides. A little higher temperature never hurts either, w/r to efficient carbon movement. Also, for hypoeutectoid steels, one wants to completely convert the pearlite/ferrite into all austenite, which requires a higher temperature than normally used for hypereutectoid steels. Hypereutectoid steels are rarely quenched from an all austenite temperature. We want some carbides left over for various reasons.
 
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