Quick Answer
Materials to avoid in folding knife construction include high-carbon content with high sulfur levels, such as brass and bronze, due to their tendency to corrode. Also, titanium alloys with high nitrogen levels can be brittle and prone to cracking. Avoid using these materials for stress-bearing components.
Poor Material Selection
Folding knives are subject to high stresses and impacts due to the folding mechanism and potential drops. Choosing materials that are prone to corrosion or cracking can lead to premature failure and compromise the knife’s performance. For example, using a brass or bronze spring for the folding mechanism can result in corrosion and failure over time.
High-Carbon Content Issues
Materials with high carbon content, such as 17-4PH, can be difficult to machine and may require specialized tools. These materials also tend to be more prone to warping and distortion during heat treatment. For a folding knife, it’s essential to balance strength, durability, and machinability. A material like 420HC, with a moderate carbon content, may be a better choice for the blade.
Titanium Allergy
Titanium alloys are commonly used in folding knives due to their high strength-to-weight ratio and corrosion resistance. However, using high-nitrogen titanium alloys can lead to brittleness and cracking. A lower-nitrogen content alloy, such as Ti-6Al-4V, is generally a safer choice for folding knife components. This alloy provides excellent strength, corrosion resistance, and machinability, making it an ideal choice for stress-bearing components.
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