Whether grafted composites or sandwiched laminates, ‘composite’ steel blades bring a geeky technological edge to your edged tools. Are they worth the extra complexity and expense vis a vis monolothic-steel blades?
The top photo shows a Kershaw ‘Rake’ and its distinctive grafted steel blade. The body of the blade is Sandvik 14C28N stainless (a perfectly decent blade steel in its own right) and the edge is D2 carbon steel.
This photo shows a similarly-made Kershaw folder. The benefits of this construction method are several. In additional to its obvious visual appeal, the D2 cutting edge can be made much harder than you’d want the rest of the blade to be. 14C28N is also far more resistant to corrosion than D2, giving this composite blade a trifecta of desirable qualities: a sharp/tough edge, a less brittle body, and easy corrosion maintenance.
In addition to being more practical than an over-hardened and slightly corrosion-prone D2 knife, Kershaw’s composite construction is also cheaper. D2 is tool steel, and when you use steel tools on it they wear out very quickly. Using a smaller piece of D2 means fewer worn-out drill bits, mill heads and grinder belts.
The sawtooth pattern in the steel is where the two steels meet and weld together. The zero-tolerance jigsaw puzzle pattern would have been all but impossible before the age of CNC mills and laser cutters, and provides a metal-to-metal interface which is in fact stronger than either of the component steels by themselves.
Kershaw tested the bejeezus out of these composite blades before selling them, and their failure testing showed that the blades never separated at the seam. (Follow the thread here, if you’re interested.)
But jigsaw-seamed composites aren’t the only game in town when it comes to composite-steel blades. The older method of laminated or ‘sandwich’ construction has been around for uncounted centuries. Handicapped by the shortage of quality ores in the mineral-poor home islands, Japanese swordsmiths turned necessity into the mother of invention. They made the most of their meager resources by building up their blades from several different types and qualities of raw iron.
Laminated blades have been around a long time, and they continue to thrive in this age of rare-earth alloying agents and powdered-metal supersteels. This 3″ Al Mar paring knife has a VG-2 core sandwiched between outer layers of much-softer (and unspecified) ‘400-series’ stainless. The outer layers provide corrosion resistance and flexibility, and the harder core does the cutting.
In the age of supersteels, the main benefit of these laminated blades is economy: this one runs about $70, which is less than a similar knife of all VG-2.
At the bottom end of the price scale, as always, are Mora knives. In addition to their traditional carbon steel and more modern stainless blades, some Mora designs are made in laminated carbon steel.
The edge is ultra-hard carbon steel (HRC 60-61) with softer carbon steel on the outside for toughness. The softer sides of the blade don’t give much corrosion resistance, but the astoundingly low price might make up for that. Most laminated Moras only cost $30 to $50.
To sum it all up, composite steel blades are a way to get the best performance from different types of steels by using them in different parts of the same blade. They’re the solution to a problem that modern metallurgy has largely solved: supersteels combine outrageous hardness, toughness and corrosion-resistance all in one metal. But these supersteels are super-expensive to manufacture and even more expensive to work with. And once you’ve bought them, they’re usually a bitch to sharpen.
I don’t own any composite or laminated blades, and I hardly think that my knives are inferior for not having them. But they’re still an interesting technology, and I’ve got my eye on one of these composite Kershaws to send Nathan for testing someday.