Choice of steel and heat treatment is directly related to the durability of the knife. My goal is your survival. Many knives are brittle as the steel must be hardened in order to hold an edge. Breakage is possible with the application of lateral force. Tempering removes some of the brittleness, but the softer the steel the less edge holding ability. Modern CPM steels negate the need for ultra hardness somewhat, but the brittle factor remains.
ZONE tempering is stock on every Relentless knife. It is a process that has been perfected by Japanese Samurai sword makers and used for thousands of years. It is time consuming and difficult, but the end result is a knife with great break resistance as well as edge holding ability. ~
ZONE TEMPERING A process that imparts a spring temper in the center of the knife running from pommel to tip. This process gives you a knife that resists both bending and breaking at the application of lateral force on the knife. The steel I use is selected to enhance this process giving you a knife that is not totally unbreakable, but very nearly so with good to excellent edge holding. The spine of the knife is not soft, having the same hardness as the edge. It is also not brittle due to the use of rugged steels designed to endure. ~
Steel Chart Explained
Wear resistance=edge holding ability Toughness=resistance to strong lateral force without deformation or breakage. ~ I use the steels marked Relentless on the chart. ~ CPM 3VSuper High performance Semi stainless steel. Super performance with strength far exceeding all of the rest. More expensive due to its difficulty to work with, but an investment that will be with you for a lifetime. With properly prepared 3V steel you get a knife that will endure extreme conditions with ease. Easy to sharpen and keep sharp. ~
CPM S35V High performance stainless steel is an improved s30V formula that offers you a better finish with more strength and ability to resist lateral force. It sharpens easily compared to s30V steel with no edge chipping like s30V. It resists rust and corrosion better than most stainless steels, although more expensive. It is the best choice for a stainless extreme use knife available today. ~ 8670M/L6 Extremely rugged High Carbon Alloy steel. It has better edge holding than 1095 with twice the toughness. This is an L6 steel variant . Hard to get but well worth it if you cannot or will not afford the CPM steels. ~
2017 and beyond CPM s30V and 5160 available only by request as the other steels perform better.
What about RUST and Stain
Yes rust and stain can be a problem, even on stainless steel. Remember STAINLESS = stain- less. It stains less than non stainless but can still rust and stain if not maintained.
Interestingly the best way to STOP rust on your knife is to use it a lot. Since knives do their work via abraision, rust has little chance to form. It's like continually rubbing it with fine sandpaper depending on what your cutting. Rust can and will dull your knife as the reason it is sharp is because at the edge there is a very fine feather of steel that stands up when the knife is sharp. So keep the edge coated with a thin film of P.B. Blaster or any good oil. This repels the moisture in the air that would otherwise dull even stainless steel knives.
Myself and Lt Col Humphrey have done rust tests on the steels used in Relentless Knives. My choice for the BEST steel, CPM 3V did for sure survive 30 days submurgence in sea salt water. The result shown in the photos below. The knife was easily still useable and quickly brought back to new again. No oil was used to protect the knife.
Our tests were done before s35V was available. CPM s30V rusted 2 days after a sea salt water bath. It was left unattended and not dried or rinsed with fresh water. ~ 8670M/L6 Rusts easily if not maintained . It can benefit from KG Gun Kote, Dura Coat, Gun bluing, or Parkerizing.
When failure is not an option, equipment that won't fail is your only option. Incorporating the most durable steels, exotic heat treatment and Trademarked Tri a symetrical grind gives you extreme break resistance, exceptional edge retention, and a strong sharp point resulting in unequaled functional reliability.
Copyright 2016 by Daniel M. Certo Additionally, no material from this site may be copied, reproduced, republished, uploaded, posted, transmitted, resold, or distributed in any way without Daniel M. Certo's written permission. All rights reserves, and all Copyright,Trade mark and Patent laws strictly enforced