Heat Treatment multiplies the overall performance of folding Knives Steel, here’s how

Pocket Knives

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According to the experts, the heat treatment procedure is undoubtedly one of the most critical processes in the production of solid and reliable Folding knives. If an adequate amount of heat treatment isn’t provided to the knife, there is a big chance that the knife will fail at some point throughout its intended use, and edge retention would keep suffering. 

You may think that the term “heat treatment” implies that this procedure includes only heating the knife’s blade, but you should know that the cooling process is as crucial as heating in this kind of procedure. How you cool the blade after heating determines if you receive the desirable characteristics, harmful properties, or no such results.

How you cool the blade after heating determines if you receive the desirable characteristics, harmful properties, or no such results. Note that the temperature used by you to heat the steel blade also plays a significant role. If you want to achieve different kinds of physical characteristics using heat treatment, you need to take your knife to the molten state.

The Importance of Heat Treating Knife Steel

The reason why you should use the heat treating process is to improve the blade’s toughness. Significant reasons include: strengthening its strength, improve flexibility, eliminate internal stresses, or lessen the coarseness of the blade’s grains.

Methods of Heat Treating Blade Steels


Quenching means to heat the knife steel very fast so that its steel becomes red hot and then again its instant cooling; this results in hardening of the blade. How quickly the heated knife blade should be cooled depends on the alloy used in its chemical composition. Low alloy steels need rapid cooling, preferably in oil. Other than that, some alloys need to be cooled down in the water, whereas high alloy steels require just air cooling. 

Air cooling provides more homogeneity and reduces the danger of deformation or cracking during the cooling process. If you use an ineffective cooling technique, it might cause the blade to break into fragments. The end product you get after the quenching process is the martensite.


Martensite is highly brittle, making it prone to cracking when stressed. Tempering is thus required to minimize the brittleness of a quenched blade while preserving the hardness it has obtained during the process. The heating procedure for tempering should be gradual and done with utmost care and should ideally last between 2 and 4 hours. This procedure must be repeated several times to ensure that the steel blade’s brittleness has been lost. In addition, this procedure makes the Folding knives ductile. 


In this heat treatment, the size of the grains is decreased, which composes the steel blade. Here, steel is heated to the point where its microstructure begins to change—this aids in increasing the knife’s resistance to grounding and filing.

Effects of Heat Treatment on a Knife

Changes in Size

Due to heat treatment, the blade’s size may vary by 0.0005 to 0.002 inches per inch. Alteration is influenced by the alloy its blade is made from and how heat treatment was carried out. Size changes need to be consistent. Otherwise, the blade will become distorted. IF shrinkage has been caused, it can be resolved using cryogenic treatment.

Loss in magnetic abilities

Heat treatment may cause a reduction in the blade’s magnetic properties. This usually happens due to an inadequate cooling process at the time of quenching. This issue can quickly be addressed just by introducing the blade to low temperatures using cryogenic treatment.


One can’t refuse or disagree with the importance of heat treating the steel of a knife. However, in case a knife does not get the heat treatment. It is for sure that the knife would not be able to withstand the pressures as the brittleness, softness, a lack of strength or an inability to keep its sharpness over a substantial amount of time would always come in the way. So, never overlook the importance of the heat treating procedure of Folding knives.


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