Too much manganese?

[running bird]

I made a post a while back asking about carburizing mild steels for a personal project. At the time I didn’t have the equipment for the project, but I recently made a big order. I’ve been become more interested i knife making and metal over the past year. so I finally use some money I put away to buy an Evenheat kiln so I can do more accurate heat treatments on my own.

Now that I really have the chance to play with metals using more accurate temperature control, I’ve been thinking over my carburization project more. I have a few questions about manganese and how it effects steel. I’m familiar with how it helps steel with hardenability. But I’ve have read that when there is too much manganese along with higher carbon contents it can make steel too brittle. I know in steels like 1095 or W2 or the white steels that manganese contents are usually a lot lower (.2-.4%). I would assume that having any more manganese would make these steels very brittle.

My original plan was to use some 1/8” 1018 as the base for this project because I have an access to a lot of it for very cheap. And I figured that if I was adding carbon to steel, and resulting in an unknown carbon continent, that the manganese in 1018 would probably help. But after receiving data sheets for the 1018 I have I noticed it says .6-.9% for the manganese. Which is a lot more manganese than even in 1075 which is .4-.7%.

Assuming after the carburizing a decent amount and forge welding, that the steel would have a carbon content of .8-1%. Would the manganese of .6-.9% would be too high and cause me to end up with steel that’s too brittle? 1018 obviously was designed around having a lower carbon content. so would raising the carbon do the opposite of what I want, turning it into an unusable steel?

Any advice is greatly appreciated.

Thanks for helping out,
Kevin

 

[jdm61]

O2 has 2% manganese and is, by all accounts, an excellent knife steel.

 

[olymon]

Sounds like you are going to spend a lot of effort to make a steel that has limited capabilities. If that's what you want to try then go ahead and do it and report your results.

p.s. just buy some good steel.

 

[running bird]

jdm.
I haven't heard of O2 before, I didn't think there were any steels that used that much manganese. So I guess that .6-.9% isn't too much of a problem to worry about.

olymon.
I have plenty of cutlery steels I use whenever I make knives. This is a project for myself, something that I thought would be fun to try. I'm not worried about this steel not being that great, I'm expecting the steel to kind of suck. I had some left over 1/8" 1018 offered to me for $1, I don't really have much use for stock that thin but took it anyways. So I tried to come up with a project for it.

I definitely will post results once I get around to this project though.

 

[MBB]

According to one of my heat treatment books, manganese <2.0% is beneficial, with improved hardenability, tensile strength, and hot workability of the steel. From 2.0-10.0% manganese, the steel is embrittled. One steel is useful above 10% manganese, Hadfield steel, with 1.1-1.4% C and 11-14% manganese (specific 1:10 ratio of C to Mn).

So realistically, the amount of manganese is the steels you discuss will not be an issue. What will be, is the unpredictable carbon content. However, if you do successfully carburize 1018, you may end up with something like 1075/1084 with the requisite need for a fast quenchant.

 

[running bird]

MBB.
Thank you, that’s exactly the information I was looking for. I knew that too much manganese to carbon was bad, but had no idea what too much is. I definety don’t have to worry about the manganese then. My hopes are that I end up with something close to 1075.

 

[MBB]

Hey, no problem, man. I was randomly reading about that the night before, so it was especially timely.