This is a question that comes back very regularly among our customers ... and the sources on the internet are sometimes contradictory! Rather than proposing a condensed information we could have found on the net, we took the party to go to Larrin Thomas directly, doctor in metallurgy - that many of you know thanks to his blog Knife Steel Nerds, The Bible for the Kings, and also at the origin of the famous Cutlery Steel Magracut! Discover his answers in the interview below:
Hello Larrin, and thank you very much for taking your time to answer us! First question, paramount: Can we forge stainless steel?
Larrin Thomas: Yes!
But to go further: Why is it so hard to forge stainless steel? Can someone do it with basic workshop tools?
Larrin Thomas: Stainless steel can be forged with basic tools. However, stainless steels have a narrower forging range than carbon steels: they can easily crack when forged at high temperatures. A widespread error in the middle wants to believe that stainless steel requires being subjected to high temperatures to be forged. This is not the case: on the contrary, some shades are very sensitive to overheating.
The overheating causes crumbling during the forge, and the blacksmith may think that it is necessary to climb higher in temperature to correct the shot: which, on the contrary, only makes things worse. It is a mistake that can also be encountered in blacksmiths from a "simple" steel such as the 80crv2 with more carbon-loaded shades: the higher the carbon level, the lower the melting temperature. This is also the reason why the melting has an extremely high carbon content, it is easier to reach its melting point to melt it.
Finally, grain joints melt first, which can also cause problems during the forge.
Is there a real technical advantage to forge stainless steel, beyond creating damask kits?
Larrin Thomas: Forge stainless steel has at least as much advantages as to forge simple carbon steels and weakly allied tool steels. We can always debate the advantage of forging a knife blade, minimal in most cases. With simple steels, carbides dissolve at "typical" forge temperatures, which means that the forge is not necessary to improve the carbide structure. With strongly alloy tool steels and stainless steels, these carbides remain present until the merger, so that it is possible to fragment them more during the forge. In addition, during the forging knife blades, the orientation of the carbide bands can be moved under the hammer so that the latter follow the shape of the blade.
Why are martensitic stainless steels so difficult to weld between them? How to weld them without encountering problems?
Larrin Thomas: Stainless steels form stubborn chrome oxides that conventional flows can not eliminate. Therefore, the best approach to welding martensitic stainless steps between them is to do it in an oxygen-free environment (NDLR: in vacuo, to avoid oxidation)
What are the stainless steels that are best for the forge? Similarly, what are the shades that are forged less well?
Larrin Thomas: On the principle, all stainless steels can be forged. After all, their manufacturer forged them before you sell them! The steels develop less forging temperature / smaller carbide carbide are generally easier to forge. AEB-L (NDT: or 12C27 ofAlleima, very similar in its composition) is a good steel to start, for this reason, but also because it is quite cheap. The main disadvantage of this nuance remains its dimensions: the thicknesses available on the market are generally insufficient for blacksmiths who like to have material under their hammer.
Let's talk about Damascus Stainless steel! What are the shades that give the best contrasts when they are properly revealed?
Larrin Thomas: It's a vast question, and an area that deserves to adventure more deeply in the future! The best contrasts are usually obtained when you are married martensitic steels (440C, AEB-L, Magnacut, S30V, 154 cm ...) with austenitic steels (304, 302 ...) or nickel.
However, the big difference between the carbon rates between these two families and the high chromium rate of austenitic stainless steels can lead to the formation of important carbide in austenitic steels, which reduces toughness.
A "double carbon" double "double carbon" mixture is known by Damasteel In its DS93X range, with the PMC27 and the RWL34 - we can get equivalents by marrying nuances like 12C27M with 154cm or RWL34. The high molybdenum content of the 154cm gives it a high contrast when revealed with hydrochloric acid. However, many other "double high carbon" mixtures have been used without containing high molybdenum steel - for example, Balbach used Nitro-B and N690CO, or 7C27MB2 and 19C27.
To start, you can base this kind of alliances before experimenting with others!
A huge thank you to Larrin Thomas for his time and valuable answers! You can find his search job on the blog Knife Steel Nerds, as well as in his book, "Knife Engineering", available on Amazon (English only). He also published a comprehensive study of the story of cutlery steels, last year. "The Story of Knife Steels"Also available on Amazon.
