The heat treatment of saw blades primarily aims to simultaneously improve the hardness of the teeth and the overall toughness, making them both wear-resistant and less prone to breakage during cutting. Common saw blade materials undergo overall heat hardening after forming. This involves heating within the austenitizing temperature range followed by rapid cooling, transforming the matrix structure into martensite, thereby increasing overall strength.
After overall hardening, tempering is typically performed to reduce internal stress and improve toughness. Without tempering, while the saw blade will have high hardness, it will become brittle and prone to breakage under stress or vibration. The tempering temperature is generally adjusted according to the material to achieve a balance between hardness and toughness, a crucial step in ensuring the saw blade's lifespan.
For high-performance saw blades, localized heat treatment processes are also employed, such as induction hardening or laser hardening of the teeth. The teeth are heated to a high temperature and then rapidly cooled, resulting in high hardness at the tooth tips, while the back of the saw retains better toughness. This "hard at the front, tough at the back" structural design makes the saw blade less prone to breakage under impact and bending, while ensuring the wear resistance of the cutting edge.
Some special-purpose saw blades also undergo surface strengthening treatments, such as carburizing, nitriding, or coating processes, to further enhance their wear resistance and fatigue resistance. These processes are typically used in metal cutting or high-strength material processing, ensuring the saw blade maintains stable performance under high-load conditions.
