Month: July 2019

History - Articles - Books

XHP Steel – History and Properties

Larrin

Thanks to John Bates, Kenny Lazarus, Robert Abel, and Matt Danielson for becoming Knife Steel Nerds Patreon supporters! I have some exclusive Patreon supporter content this week. Pete of the Cedric and Ada Youtube channel posted this past week a video summarizing his rope cut tests on 14 Spyderco Mule knives in different steels. This is a fun test because all of the knives are nearly identical and only the steel and heat treatment is different, so it is a better steel comparison than some of the others between different knives. I already have a previous article where I compared CATRA testing to rope cutting so this new test didn’t warrant a whole new article, but I offered an analysis of his test for Patreon. read more

Forging

Forged vs Stock Removal Knives

Larrin

Thanks to Colin Fergus and funny_name_here for becoming Knife Steel Nerds Patreon supporters!

Forging by the Steel Company vs Bladesmith

When the steel company makes the steel they produce a large melt of the steel with the desired composition and pour it into a mold which solidifies and produces an ingot. A typical ingot size for tool steel or high speed steel might be 10″ thick either round or square depending on the production process and the desired final shape. Smaller ingots are better for limiting the segregation of alloying elements and keeping the cast structure fine. At that point the steel is in “cast” form. The ingot is then heated up to high temperature and forged either with a hammer or press to a form ready for hot rolling. In some cases the ingot is ready for rolling as-produced. Next the steel is hot rolled to the final desired thickness. Hot rolling in an industrial setting is typically done with relatively few reheats, typically single digits. That depends on how much reduction in necessary, how difficult the steel is to work, and the capability of the rolling mill. read more

Carbides, Steel and Knife Properties

Carbide Types in Knife Steels

Larrin

Thanks to Todd Kroenlein and David for becoming Knife Steel Nerds Patreon supporters!

Cementite

The most basic carbide type in steel is an intermetallic compound formed between iron and carbon, commonly called cementite. Carbides are hard and brittle, similar to a ceramic material. Cementite has a relatively complex structure but in its simplest form it is 3 iron atoms for every carbon atom: Fe3C. However, other elements can partially replace the iron, so the carbide is sometimes given as M3C where M can mean Fe, Mn, Cr, etc. Cementite is typically present as either particles or in “pearlite.” I introduced what pearlite is in this article. However, cementite is the only carbide type that typically forms in pearlite, so to keep things simple for this article I will be focusing on carbide particles. Below I have a schematic representation of carbides (black circles) along with the grain boundaries (black lines). read more

Austempering, Austenitizing, History - Articles - Books

The Secret Heat Treatment of Frank J. Richtig

Larrin

Thanks to Dean Baughman, Kitoc420, Steve Callari, Jay Ghoo, and Mitch Cagile for becoming Knife Steel Nerds Patreon supporters!

Legendary Heat Treatments

Last week I wrote about What a Good Heat Treatment Can and Cannot Do, and as part of that topic I wrote about how some knifemakers have a legendary or even mythical reputation for their heat treatments. In that article I argued that the big differences are between “bad” and “good” heat treatments, and that the differences between various good heat treatments are much smaller. And that edge geometry and knife design are more important to knife performance than the differences that are possible between different “good” heat treatments. So I think it makes sense to discuss a particular case of a knifemaker known for legendary, unmatched heat treatments, which brings me to… read more

Heat Treating and Processing

What a Good Heat Treatment Can and Cannot Do

Larrin

Thanks to C6 MFG and Dan Swaney for becoming Knife Steel Nerds Patreon supporters!

The Legend of Heat Treatment

There is some debate about knives that have steel with a “good heat treatment” vs those that have a bad or sub-par heat treatment. Some knifemakers have a near legendary reputation for their excellent heat treatments. What exactly is possible in terms of heat treating? How much better can steel be? How bad can it get? read more