Like most blade steels, the best way to understand the “magic” of K390 is to start with the reason it was developed in the first place. According to its creator, BÖHLER, K390 MICROCLEAN® was developed to “meet the demanding wear resistance and compressive strength requirements of cutting, blanking and punching applications, for cold forming applications, and for parts which are subjected to abrasive wear in plastics processing.” In simpler terms, K390 was created specifically to excel at some of the most demanding industrial processes imaginable.
K390’s remarkable qualities include good machinability, excellent grindability, uniform low dimensional change during heat treatment, excellent tolerance for long soak times during heat treating, and optimal EDM (electrically discharged machining) characteristics. The key to achieving these properties is BÖHLER’s advanced powder-metallurgy production process, which prevents alloy segregation and ensures a uniform chemical composition, uniform carbide distribution, and small carbide size.
As impressive as all this sounds, when it comes to appreciating K390’s potential as a blade steel, it helps to have other established steels as a basis for comparison. It helps even more when a steel-savvy custom knifemaker and popular Spyderco collaborator “cracks the code” for you.
K390’s remarkable qualities include good machinability, excellent grindability, uniform low dimensional change during heat treatment, excellent tolerance for long soak times during heat treating, and optimal EDM (electrically discharged machining) characteristics. The key to achieving these properties is BÖHLER’s advanced powder-metallurgy production process, which prevents alloy segregation and ensures a uniform chemical composition, uniform carbide distribution, and small carbide size.
As impressive as all this sounds, when it comes to appreciating K390’s potential as a blade steel, it helps to have other established steels as a basis for comparison. It helps even more when a steel-savvy custom knifemaker and popular Spyderco collaborator “cracks the code” for you.
| Phil Wilson is an accomplished custom knifemaker who specializes in the use of exotic, high-performance steels and the sophisticated heat-treatment voodoo necessary to wring the maximum performance out of them. At a basic level, he explains that K390’s alloy composition is similar to A11, a very high carbon, vanadium-enriched ingot tool steel. When A11’s alloy formula is produced with the benefit of powder metallurgy technology, the result is Crucible® Industries’ CPM® 10V—one of Wilson’s favorite blade materials. K390 takes this evolutionary process even further, tripling the amount of molybdenum and adding 1% tungsten and 2% cobalt. This enhanced composition further increases K390’s strength, hardness, hardenability, and toughness and gives it an attainable working hardness of RC64. In a post on the Spyderco forum, Wilson provided further insights into both the history and performance of K390: I have been using K390 from the start, ever since it was introduced by Bohler and I got some small samples to try. A bit of history is that it is the European version of CPM 10V but not the exact chemistry (about 1% less vanadium plus small addition of a few others). That is because the CPM 10V chemistry was protected by patent at the time. If you check the K390 data sheet, it claims that the bit less vanadium gives K390 a little boost in impact toughness. It also can be heat treated at a lower temperature than 10V. So it is pretty much the same as the A11 grade, but different in a few small details. It is hard to tell the difference between CPM 10V and BU K390 in the real world in my experience. I like both grades and they are the baseline (along with Vanadus 10 and K294) from which I measure wear resistance. The 5% chrome is there to make them all air hardening, among other things, and does not contribute much to corrosion resistance. It is going to make a killer knife... Phil Spyderco has long been an industry leader in “pushing the envelope” of performance through the use of exotic, state-of-the-art steels in our knives. In addition to our own relentless commitment to Constant Quality Improvement (C.Q.I.), we have the extraordinary benefit of the wisdom and experience of collaborators like Phil Wilson. Our K390 family of knives is a direct reflection of that dynamic synergy, and yet another example of what makes Spyderco and our knives distinctly different. |