What is Powder Metallurgy?

[Larrin]

In this article I describe the process of powder metallurgy including:

How does powder metallurgy refine the microstructure of steel?
When was powder metallurgy invented and which company was the first to use it?
What were the early steels used with powder metallurgy and how were steels developed differently to take advantage of the technology?

https://knifesteelnerds.com/2018/08/20/what-is-powder-metallurgy/

 

[GatorFlash1]

Great article and website. Thanks for posting. I was thinking that powdered steel was a steel ground from a casting into tiny powdered bits and then recasted and forged. I never realized it was produced with something like a super duper paint sprayer spraying bits of the molten steel alloy into a cooling bin. Very interesting.

 

[stonproject]

In this article I describe the process of powder metallurgy including:

How does powder metallurgy refine the microstructure of steel?
When was powder metallurgy invented and which company was the first to use it?
What were the early steels used with powder metallurgy and how were steels developed differently to take advantage of the technology?

https://knifesteelnerds.com/2018/08/20/what-is-powder-metallurgy/

Very interesting website. I wound up reading about the CATRA test on edge angle with the 154 steels. Really cool stuff!

 

[jbmonkey]

another great article Sir. thanks for sharing.

 

[Alberta Ed]

Spyderco's catalogue (you can download) has an excellent section on powder steel metallurgy, too.

 

[Legendary_Jarl]

This is quite an education. Thank you for sharing.

 

[DocJD]

Great stuff ! I had a vague idea that that the powder steels are better but know I why .

 

[Glenn Goodlett]

Like most things, there is more to it than you would ever dream. As much as we try to simplify it, the world is a complicated place.

 

[Larrin]

Like most things, there is more to it than you would ever dream. As much as we try to simplify it, the world is a complicated place.

What extra complications would you like to add?

 

[Revolverrodger]

One thing I din’t understand is that you say in one of your articles that RA increases toughness. So cryo would decrease toughness

 

[Mo2]

One thing I din’t understand is that you say in one of your articles that RA increases toughness. So cryo would decrease toughness

Cryo increases toughness and edge retention.

 

[Larrin]

One thing I din’t understand is that you say in one of your articles that RA increases toughness. So cryo would decrease toughness

In general cryo does decrease toughness. But there are always exceptions.

 

[Revolverrodger]

Cryo increases toughness and edge retention.

Data presented by Larrin tend to disagree with your statement

 

[Mo2]

Data presented by Larrin tend to disagree with your statement

I've read alot about it too, so I'm confused. Alot of what I've read has said otherwise. Being that his background is knives and heat treatment I'd take his word over what I've read. Though I do recall reading on the forum that cryo gives a point of hardness with no decrease in toughness but I've also read from sites doing cryo services that it gives more toughness.

 

[dirc]

Larrin shows it like it is... in some cases, certain alloying elements in specific quantities could cause a reversal of what you expect, often depends on how they come together in certain HT regimes, and the growing (or lack thereof, or shrinking) of carbides. When you cryo, the low temp can exacerbate the problems, or, with a good HT & alloy mix, the problems are not there, and thus the cryo does help.

 

[Revolverrodger]

Larrin shows it like it is... in some cases, certain alloying elements in specific quantities could cause a reversal of what you expect, often depends on how they come together in certain HT regimes, and the growing (or lack thereof, or shrinking) of carbides. When you cyro, the low temp can exacerbate the problems, or, with a good HT & alloy mix, the problems are not there, and thus the cyro does help.

Metallurgy is definitely not a simple science

 

[Larrin]

Warren heat treated some Z-wear that I tested where no change in toughness was found with cryo (but it did increase hardness slightly thereby improving the hardness/toughness balance): https://knifesteelnerds.com/2018/06/04/toughness-testing-cru-wear-z-wear/

But in that article I said this: “Because of the overwhelming amount of research showing that cryo tends to lower toughness somewhat means that we probably can’t take this result as a hard and fast rule. Perhaps the retained austenite in the non-cryo version of Z-Wear didn’t have the right level of stability to improve toughness or there was too little of it to make much difference.”

 

[Glenn Goodlett]

What extra complications would you like to add?

I don't have anything to add, I'm just shocked at how complicated the whole process seems to be.

I should have added in my first post that I thought it is a interesting and well done article. Thanks

 

[Larrin]

I don't have anything to add, I'm just shocked at how complicated the whole process seems to be.

I should have added in my first post that I thought it is a interesting and well done article. Thanks

Got it.