5160 forging temps & heat treat

[Tim Lemke]

I'm reading up on this in bladesforum.com but figured I'd ask for some further data.

A steel comp site said to forge between 2200 and 2100???? That is really hot and narrow! I'm not sure that's applicable to knife making with forge anvil and hammer, rather than hot-roll ideal temp. This has me biting my fingernails figuratively, surely it ain't that dodgy.... Anyone got a minimum steel working temp you'd suggest? You can speak in terms of color too, that's what I'm most familiar with anyways, but a degree at which to cook would be highly appreciated. Can it be smoothed of hammer marks at red heats safely at least?

I'm seeing that it takes a usual vermiculite anneal good enough, and I'm glad of it. All my stock is hammer blanks from bonfire annealed forklift tine, truck coil spring, and annealed as needed leafspring, all hard working parts, so I would think I'd like to normalize before and after forging to make sure I do not pound in extra fatigue. Anyone have cautions towards this approach? I'd like to know.

Dooooooon't think I want to touch the triple quench some folks have touted with pretty much any chromium steel. Sounds ridiculous, and turns two HT heats into five! I don't want decarb! Says mid speed oil so gonna go for canola oil as parks 50 may be too fast if it says preheat the canola.

The steel comp site said 800°F temper???? I don't have that capacity in my oven! That's temper as for use as spring, right? *frets*

 

[EdCaffreyMS]

5160 is easy to forge, and is VERY forgiving of mistakes. I read your entire post and can't help but wonder if you were actually reading information concerning 5160..... if you were, I just can't wrap my head around any of that. I've forged and built blades of 5160 for over 3 decades, and have never heard/read those numbers in association with it. I've always forged from the aspect of using the first 2-3 "heats" as my highest temps... usually in the 1700-1800F range, to move as much material as possible, and I then reduce successive heats until I'm down to a medium read at finishing/the last heats. There's only 60 points of carbon in 5160.... I've never tempered ANY 5160 blade at more than 400F, and those I've used to win cutting competitions with were usually tempered at 350-375F. (by the way, ALL of the 5160, 52100 and SUJ2 blades that I've won cutting competitions with were of the multiple quenched variety)

When it comes to "normalizing" ,that should be a "standard practice" with any blade steel you forge. Not doing it is simply asking for problems.

Finally, DO NOT rely on information you find on the web! There is SO MUCH misinformation out there, especially when it comes to Bladesmithing, that's it's just laughable. If anything, use the information as a starting point only. Were it possible to eliminate all variables from both individuals, and their shops/work environments, information found on the web MIGHT be consistent/relevant, but things being as they are, with differing conditions from shop to shop, do not expect the first, or even the second or third blade from any "new" steel you try to be "right"...... you have to break a few eggs to make a cake, and that same mindset applies to forging blades.

 

[Andre Grobler]

I recently read Verhoeven’s pdf and he reported on a method of grange of normalizing at 900 degc or 1650f for 15minand quench and then three cycles of 790 degc for 4min and quench in oil... then take to austenitizing temp 830 degc and quench... it gave me decent grain i think and hardness figures. Like rc62-ish as quenched for quite thick sections... below is a funny pic of the as delivered steel soaked at 830 and quench and the bottom one was refined... no tempering... so that worked but it may have worked better if it could be heated quicker than in my kiln... so if you have a forge it might work but i think temp control is critical... so a forge might not be a good idea... i am sure my refinement was not as fine as it could be with better equipment but then again it may not have hardened very well... i tried a normalise at 900 degc air cool, soak at 815 degC and air cool and soak at 790 and aircool... then soak at 830 and quench... this hardened quite poorly especially in the thicker sections... so the grain may have been too fine... i posted the results on hypefreeblades so it may be worth taking a look there... i suspect there is better ways than i used...

 

[Doug Lester]

You're right, 2100°-2200° F is too high to work 5160 at. That's near to welding temperatures. It also appears that you are working with mystery metal and assuming that it is 5160. Now with the leaf spring steel is probably going to be 5160 or something close enough to use that as a starting point. The coil spring is a maybe and the fork lift tine left overs I don't know about. Not long ago we had someone who posted that he ran into a problem that after working out the heat treat for a bundle of leaf spring he ran into a couple of pieces that didn't respond the same. So, if you can, you would be doing yourself a favor by starting out with known steel rather than salvaged steel.

I'm really hesitant to say what color because it can be misleading according to ambient lighting and the way one sees color. I've yet to see cherry read at my forge but I would say an orange or a red is probably the right color. The temperatures given above would be almost a yellow and would result in grain growth, especially if you held the steel at that temperature for long.

Annealing or normalizing before forging is just spinning your wheels. Whatever you do will immediately be undone as soon as you bring the steel up to forging temperature. Normalizing after forging is a good idea to relieve stress. Thermal cycling is good to do after the initial grind and before the quench to refine the grain. I'm not a fan of annealing because it can cause aggregation of carbides which can cause problems with drilling or putting a really fine edge on the blade. Normalizing will get the steel plenty soft to grind.

I don't want to open a can of worms here but I'm not a fan of triple quenching either. Even though 0.6% carbon is not going to create as much plate martensite as, let's say 52100, each quench can cause microscopic cracks where the plates intersect. Of course you can minimize this by quenching for about 8 seconds and then allowing the steel to cool to where it's warm to the touch. The allows the steel to rapidly cool to under the nose of the cooling curve and maybe to just past the Ms point and then allow the steel to cool in air past the Mf point.

If you are wanting to see if your steel is the right temperature for quenching it would be good if you learned to spot decalences. You could do a web search or look on YouTube to see what that looks like but basically is looks like a shadow passing across the blade and indicates phase change better than using a magnet which can be misleading because steel becomes non-magnetic just before phase change. The reverse of the process is called recalesence and looks the same but just as temperature decreases.

Doug

 

[Kevin R. Cashen]

2,200°F is the maximum forging temp. for 5160. You can work it anywhere from 1600°F up to that. It is pretty simple, the more metal you have to move, the more heat you give it. Cut the 800°F in half for the tempering of blades. There are a lot of heat treatments based upon belief, I always just looked at what was actually happening inside the steel and proceeded accordingly, the actual metallurgy of it normally gets it done with very straight forward methods.