Transmission gears often work under conditions of high speed, high load, and continuous rotation of speed and load. In addition to normal wear and tear, gears may also cause gear shocks, poorly gnawed gears, and start jitter due to lubricating oil quality, poor lubrication conditions, improper driving operations, improper gear assembly positions during maintenance, etc. And so on, will accelerate the wear and damage of the gear. Gears rely on their own structural dimensions and material strength to withstand external loads, which requires materials with high strength, toughness and wear resistance; due to the complex shape of the gears, the gears require high precision, and the materials also require good manufacturability. The commonly used material for transmission gears is forged steel.