How to do the heat treatment of stainless steel bearing steel balls?
= 'Font-Size: 16px; Font- Family: boldface, SimHei; Color: rgb (0 0 0); According to the analysis of heat treatment process, FAG Bearing steel balls are not spheroidized and annealed due to waste heat quenching after forging, so the grains are coarse and there are banded structures; At the same time, the carbon content in quenched martensite is very high, and the water inlet temperature in Quenching after forging is too high, which increases the quenching stress of steel balls. The analysis shows that the West 120 steel ball is quenched by water cooling, the temperature distribution is very uneven, forming a very high tissue stress, and its surface is in a compressive stress state. Internal tensile stress is the main cause of workpiece fracture.
In addition, the bearing steel ball has strong water quenching cooling ability, and the layered structure in the workpiece is coarse, and there is a hard structure near the center, the core of the workpiece has poor toughness and there is a hidden danger of crack and cracking. In the production of workpieces, tempering is not carried out in time after quenching, and the stress after quenching is very high and has not been eliminated and released, thus causing cracking and damage of steel balls. Analysis shows that quenching cracking of bearing steel balls is closely related to forging and heat treatment process. Improper forging heating time or temperature control causes the steel ball to overheat or overburn, so the grain is coarse and the toughness of the workpiece decreases. On the other hand, the forging deformation of the central part of the West 120 steel ball is small, and the cooling rate is also small. Therefore, the recrystallization grain in this part is coarse, which causes the steel ball crack fracture to occur in the middle.
to sum up, the improvement measures to prevent cracking of high carbon martensitic steel balls are proposed as follows: forging. Increase the forging ratio, strictly control the forging process, and prevent the core structure from being bulky after forging. Reducing the quenching water inlet temperature of bearing steel balls and increasing the outlet water temperature can obviously reduce and ease the quenching stress of workpieces. Before quenching, spheroidizing annealing is increased to refine the structure so that the workpiece is fine needle-shaped after quenching (Fine sheet . )Martensite prevents coarse structure after quenching. After quenching, temper in time to eliminate quenching stress, stabilize the structure and further remove the hidden danger of workpiece cracking. After the above process is improved, the quenching cracking failure phenomenon of FAG Bearing steel balls is eliminated, the quality of workpieces after heat treatment is excellent, and the production operation is good.