Forging Stepped Shaft for Cold Rolling Mill Transmission Box

Material selection

The basic material is mostly medium high carbon alloy structural steel (such as 42CrMo, 35CrMo, 20CrNiMo), which achieves comprehensive performance of "high strength+high toughness+wear resistance and fatigue resistance" through a combination process of forging and heat treatment.

Surface treatment

Key surfaces can be further improved in surface hardness (up to HRC58~62) and fatigue strength through carburizing quenching, high-frequency quenching, or shot peening, avoiding surface wear and fatigue cracks.

Structural characteristic

It is mostly a stepped shaft or spline shaft structure, and the shaft diameter is designed in stages according to the magnitude of the force. The transition part adopts large rounded corners or chamfers to avoid stress concentration - this is the key structural detail to deal with rolling mill vibration and impact.

Quality inspection

Multiple non-destructive tests are required: ultrasonic testing (UT) after forging to identify internal defects, magnetic particle testing (MT) or penetrant testing (PT) after machining to inspect surface cracks, and hardness testing and tensile testing are also required for critical areas to ensure performance meets standards.

Steel grade

This type of material is medium carbon alloy steel with high strength, high toughness, good wear resistance, and fatigue resistance., which is subjected to quenching and tempering (or normalizing) heat treatment to improve its processing performance.