Tempering 60Si2MnA ? Hard to find on color charts

falselycondmdlabrat said:
found the temper was much higher an longer then non.alloy steel and is hard to find on basic color charts
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Fine ill just talk to myself i done a few runs at this an the first drew back to a nice dark straw an broke the tip off, second drew back at 400 for 3 hours an was a dark brown an purple still chipped the edge. So at this point i did more diggin an found that can be tempered between 375 and 575 so i went as high as oven would almost go at 520 for 4 hours to a grey light blue. An its still hard as ever i just dont know havent broke it yet but could this be within a normal range?
 
falselycondmdlabrat said:
found the temper was much higher an longer then non.alloy steel and is hard to find on basic color charts
Click to expand...
Fine ill just talk to myself i done a few runs at this an the first drew back to a nice dark straw an broke the tip off, second drew back at 400 for 3 hours an was a dark brown an purple still chipped the edge. So at this point i did more diggin an found that can be tempered between 375 and 575 so i went as high as oven would almost go at 520 for 4 hours to a grey light blue. An its still hard as ever i just dont know havent broke it yet but could this be within a normal range
polish avenger said:
So, this is Chinese 5160?
What is your hardening procedure?
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I do a normalizing with about five minute soak an then air cool then the heat treat pretty much the same way by visual i have a infred gun but im convinced its all over the place so ya. Oil quench
 
If this is being heat treated in a forge, I suspect you've overheated it. Properly held temps and soak times are your friend.
 
Yea ide agree there just seem to different temps an info every time i search i really dont feel its an over heating but then again maybe this steel looks an burns different. I went easy on the soak for thickness in relation to whatever recommended control may been an those are pretty hot anyway ...maybe time to upgrade this system
 
Like i said it hardens just fine its getting it to come back is troubling. I searched again an it recommended 750°c for 90min which is why i figured the 500 doubled...an the fact i cant control a temp to much past there🫣
 
If your forging, "normalizing", and HT were done too hot you may have massive grain growth. This will still harden quite well, but no mater what the tempering can break and chip easily.
 
Why are you using color to determine how much it was tempered? An oven where you control the temperature is much more reliable.
 
I see people using 375 for tempering for 9260, which is supposed to be close to your steel. Many steels get Tempered Martensite Enbrittlement above 450, so that may be going on, too.

How does the grain structure look at the tip break? Does it look like powdered sugar or granulated sugar/salt?? If it's not velvety smooth and looks more granular like sand, you cooked the steel and the grain is massive and will be brittle at any real hardness. But since you tempered to a light gray color, it's probably pretty soft already, so if it's still breaking, its most likely large grain from overheating during the quenching.

How are you testing the hardness??? Chisels, files, hardness tester, or seeing if it breaks?

I am guessing it was way overheated at some point and the larger grains are why it's so brittle. Do you have any real idea what temp you "normalized" at or quenched at?

Did you forge the steel or stock removal? Was it repurposed steel, ie old springs? Those may have existing stress fractures. Is it a short blade or a sword? Short blade, temper in your kitchen oven and start off at like 325 degrees or so and put the blade in AFTER it's been at temp for a while. Ovens can be pretty off temperature wise and can get a lot hotter than the set temperature while heating up, too.

Or are you tempering in your oven/torch and just looking at the colors? The steel needs to be ground clean and thoroughly cleaned/degreased to use colors since contaminants can change color before the steel does.

Tempering colors don't change all that much with different steels, so light straw should be around 400, not dark purple.

Infrared and laser temp devices do not do well with hot steel, so they are not accurate.

Doubling the tempering time at 500 degrees is not the same as tempering at a higher temperature for a shorter time, either.

You may want to do more research and figure out what is going on. There are a lot of variables you are dealing with, so it's hard for people to answer when the info is all over the map.

If it was brittle at "dark straw", its most likely a large grain issue, or it's not the steel you think it is? I had a knife blanks that was 1095 I heat treated like it was AEB-L by mistake, so it was way overheated! It's 63 HRC after tempering, but super brittle and with huge grain when I broke it. Smaller grain at the same hardness shouldn't be anywhere as brittle!
 
Taz said:
I see people using 375 for tempering for 9260, which is supposed to be close to your steel. Many steels get Tempered Martensite Enbrittlement above 450, so that may be going on, too.

How does the grain structure look at the tip break? Does it look like powdered sugar or granulated sugar/salt?? If it's not velvety smooth and looks more granular like sand, you cooked the steel and the grain is massive and will be brittle at any real hardness. But since you tempered to a light gray color, it's probably pretty soft already, so if it's still breaking, its most likely large grain from overheating during the quenching.

How are you testing the hardness??? Chisels, files, hardness tester, or seeing if it breaks?

I am guessing it was way overheated at some point and the larger grains are why it's so brittle. Do you have any real idea what temp you "normalized" at or quenched at?

Did you forge the steel or stock removal? Was it repurposed steel, ie old springs? Those may have existing stress fractures. Is it a short blade or a sword? Short blade, temper in your kitchen oven and start off at like 325 degrees or so and put the blade in AFTER it's been at temp for a while. Ovens can be pretty off temperature wise and can get a lot hotter than the set temperature while heating up, too.

Or are you tempering in your oven/torch and just looking at the colors? The steel needs to be ground clean and thoroughly cleaned/degreased to use colors since contaminants can change color before the steel does.

Tempering colors don't change all that much with different steels, so light straw should be around 400, not dark purple.

Infrared and laser temp devices do not do well with hot steel, so they are not accurate.

Doubling the tempering time at 500 degrees is not the same as tempering at a higher temperature for a shorter time, either.

You may want to do more research and figure out what is going on. There are a lot of variables you are dealing with, so it's hard for people to answer when the info is all over the map.

If it was brittle at "dark straw", its most likely a large grain issue, or it's not the steel you think it is? I had a knife blanks that was 1095 I heat treated like it was AEB-L by mistake, so it was way overheated! It's 63 HRC after tempering, but super brittle and with huge grain when I broke it. Smaller grain at the same hardness shouldn't be anywhere as brittle!
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Well duly noted about doubling up on temper i can see how the tip it came off this smaller knife..i have a afinity to throw um but yes it was not powder grain structure this this thinner knife i could reason why it chipped ... but yea the other two just as hard but blued not that i was going off color or i wouldnt of said temps i just felt on all the trial tempers color seemed kinda random nonetheless i do only check by file for hardness an go for a finish before i ditch one an they are all anti creep anchors
 
falselycondmdlabrat said:
Well duly noted about doubling up on temper i can see how the tip it came off this smaller knife..i have a afinity to throw um but yes it was not powder grain structure this this thinner knife i could reason why it chipped ... but yea the other two just as hard but blued not that i was going off color or i wouldnt of said temps i just felt on all the trial tempers color seemed kinda random nonetheless i do only check by file for hardness an go for a finish before i ditch one an they are all anti creep anchors
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I liked working with AEBL the cryo an all was pretty slick i do my research an dont really mess with the trickier steals i tried a "supposed D2 " i did get from a die shop but it was tricky by that i mean my my normalization an quench temps are pretty within the bigginer range still other then those two an 1095 nicolson file ...an now this one i had read its an easy treat hardens well an does ...but your probably right about my oven being off an the peice going too long. An i felt i was just aswell try to control temp by sight an àn watch my flame an scale an spark then the temp gun. Seemed to just get me general idea of inside temp. So i just go to bright orange for any specified hold. Unless above 1700 it would be brighter but at those temps i got foil next time i was tryin boric acid.
 
Questions:
Are you saying you HT AEBL and D2 in a forge?
Did you do your 5minute normalizing in a forge?
What type of oven are you doing the tempering in?

As Taz pointed out, the colors that form on a blade being tempered in an oven are not always the same as "Temper Color Charts". You can get all sorts of colors that mean nothing at all.
 
Stacy E. Apelt - Bladesmith said:
Questions:
Are you saying you HT AEBL and D2 in a forge?
Did you do your 5minute normalizing in a forge?
What type of oven are you doing the tempering in?

As Taz pointed out, the colors that form on a blade being tempered in an oven are not always the same as "Temper Color Charts". You can get all sorts of colors that mean nothing at all.
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Thank you Taz N Stacy thats what i think i needed to hear the temp colors could mean nothing i most have missed Taz noting to the effect but i do the tempering inside kitchen oven an all my heat treat/ forging in furnace i made in garage i wish i knew how to load images of things i been trying to say but its just a shell of pressure washer boiler with a burner on top an forced air through the back and yea i did a few of each AEBL an D2 Through it cryo on both steels only seemed to had trouble on one of the biggerD2 had significant layer of decarb skin
 
At the temps needed for AEB-L and D2, you need to protect the steel or it will decarb pretty badly, especially in a forge that may be hotter than the temps you are aiming for! 309 stainless foil is recommended (2240 max temp), you may be able to squeak by with the 321 stuff (2000 max temp), but in a propane forge, you will probably need the 309 stuff or some way to protect the blade. Tips and thinner sections will heat up quicker, so will be more likely to decarb and burn the carbon out of the steel, which will weaken it, too, which may be why the tip broke. Overheating and decarb can do nasty stuff to a blade!

Kitchen ovens are good for tempering, but I would get a digital thermometer you can put the probe into the oven and see the more accurate temp. I found mine at 335 was around 350, but when I was preheating it, it was up to 400 at one point! Turn the oven on, pre heat it and let it soak for a while to even out. Some guys put a cookie sheet or 2 or other pans filled with sand in the oven to act as a heat sink and help even out the temp swings. Once mine is up to temp and soaked, it has maybe a 5 degree swing. I am going to convert my HT oven I built into a tempering oven this summer and then build a newer/better HT oven with the proper bricks. With the PID controlling the ovens, it holds within a degree usually, even at 2150.
 
Taz said:
At the temps needed for AEB-L and D2, you need to protect the steel or it will decarb pretty badly, especially in a forge that may be hotter than the temps you are aiming for! 309 stainless foil is recommended (2240 max temp), you may be able to squeak by with the 321 stuff (2000 max temp), but in a propane forge, you will probably need the 309 stuff or some way to protect the blade. Tips and thinner sections will heat up quicker, so will be more likely to decarb and burn the carbon out of the steel, which will weaken it, too, which may be why the tip broke. Overheating and decarb can do nasty stuff to a blade!

Kitchen ovens are good for tempering, but I would get a digital thermometer you can put the probe into the oven and see the more accurate temp. I found mine at 335 was around 350, but when I was preheating it, it was up to 400 at one point! Turn the oven on, pre heat it and let it soak for a while to even out. Some guys put a cookie sheet or 2 or other pans filled with sand in the oven to act as a heat sink and help even out the temp swings. Once mine is up to temp and soaked, it has maybe a 5 degree swing. I am going to convert my HT oven I built into a tempering oven this summer and then build a newer/better HT oven with the proper bricks. With the PID controlling the ovens, it holds within a degree usually, even at 2150.
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That would be cool to get digital i did grab some foil off amozon i will check if its ,,309 or 321 guess hadn't thought on the degree of pertection because im sposed to be getting a bit more D2 while im here i was trying to look on here about diricting my air in its kinda central air concept it works fair an even up through fire brick an back but i could get hot faster from a port above next to gas .but it always seemed like a cold spot smak in the center is that being too close to flame or is the air blowing to hard
 
I think he may have an air source blowing in from the back into the forge instead of having the air and gas going together to mix? I am curious to see pictures as well! I wonder if the air is blowing the heat out the front and not circulating it through the forge???

With a blown air/forced air forge (ie ribbon burner or mini ribbon as I call my setup), the air/propane mix in the tubing and come out as a jet from the nozzles; it's not a burner for the flame and a separate air source? With a Venturi burner, the air is sucked in from outside the forge to mix with the propane; controlling the air mixture controls the flame and atmosphere inside the forge.

A "central air" setup using a fan to blow the air around the forge or like a convection oven/air fryer may not work as well in this application since items in the forge will disrupt the air flow more. With the fan blowing the heat from the burner from the back of the forge to the front, the rear portion of the forge won't heat up well since the hot air is being pushed out of the forge.

This is my "QBert" forge. On the left is a port to put my nozzle into. The air comes from a blower under the forge to tubing and the propane comes into the tubing at an elbow connection. The nozzle has numerous stainless tubes welded into it, which creates numerous mini jets. It's similar to a ribbon burner, but the nozzle is around 1.75" diameter or so. I can unscrew the nozzle and reweld tubes in or replace the entire nozzle when it gets too burned out. This allows the gas and air to mix well in the tubing and get ignited

q bert1.jpg

The nozzle:
Nozzle.jpg

Forge 2134.jpg

Most venturi forges have the burner(s) mounted at the top or side and are open ended. Venturi burners suck air into the burner to mix with the gas in the nozzle. Even coal forges with blowers have the air blowing through the flame itself. It's about blowing air through the flame, or mixing the gas and air flow.

Putting a fan at the back end of a Venturi type forge doesn't do anything except blow the heat out the front. If you are doing forced air forge, the air and gas need to mix at the flame to be effective, not coming from different areas.
 
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