The heat treatment process of the solid steel ball is analyzed. Since the residual steel is not subjected to spheroidizing annealing after forging, the solid steel ball is not subjected to spheroidizing annealing, so the crystal grains are coarse and there is a band structure; at the same time, the carbon content in the quenched martensite is high, forging The temperature of the water entering the post-quenching is high, which increases the quenching stress of the steel ball.
The solid steel ball bearing steel ball has strong water quenching and cooling ability, and the inner layer structure of the workpiece of the whole product is coarse, and to a certain extent, it is mainly close to the hard tissue at the core, so that the toughness of the workpiece core is poor. There is a hidden danger of crack cracking when it is used. After quenching, the workpiece is not tempered in time. After quenching, the stress is high and is not eliminated and released, resulting in cracking and damage of the steel ball. According to the analysis, the quenching and cracking of bearing steel balls is closely related to the forging and heat treatment processes.
Process improvement measures for solid steel balls
1. Forging. Increase the forging ratio and strictly control the forging process to prevent the core structure from being thick after forging.
2. Reduce the quenching water temperature of the bearing steel ball and increase the water temperature, which can significantly reduce and alleviate the quenching stress of the workpiece.
3. Add spheroidizing annealing before quenching, refine the structure, and make the workpiece quenched into fine needle-like (small sheet) martensite to prevent coarse structure after quenching.