forging support roll

Large forged steel backup rolls are critical components of rolling mills. However, surface defects dominated by forging cracks frequently occur during the forging process, which seriously hinders process implementation and even results in product scrap. This paper mainly analyzes the crack generation causes from the production process and implementation links of forged steel backup rolls, and discusses effective prevention and control measures.

The problem of Grade 4 network carbides and a small amount of eutectic carbides in Cr5 forged steel caused by improper post-forging heat treatment design can be solved by optimizing the heat treatment process. High-temperature normalizing is adopted to dissolve most carbides into the matrix, followed by rapid cooling using water-based or oil-based quenching media to ensure full austenite transformation, reduce precipitation of secondary carbides, thereby sufficiently refining the microstructure and avoiding the formation of network carbides. Ultimately, zero defect echoes and favorable bottom echoes are achieved in testing.

Due to prolonged friction and rolling contact between the work roll and the support roll, the support roll bears significant shear and contact stresses, resulting in deformation strengthening and wear. Therefore, its main failure modes are peeling and wear. The tonnage of forged steel support rollers is large, the production process is complex, and waste products are easily generated.

The manufacturing methods of support rollers mainly include forging and casting. The hot working process of forged steel support rollers mainly includes smelting, casting, forging, and heat treatment, so that the working layer of the produced support roller body can achieve high wear resistance, high and uniform hardness, and excellent accident resistance. At the same time, it ensures that the core and neck of the roller have high toughness and strength, to ensure the dimensional accuracy and good surface quality of cold-rolled strip or steel plate.

Ultra large support roller forgings are prone to ultrasonic testing failure due to incomplete forging and compaction of the core. This time, the composite forging main deformation process of "upsetting WHF method for elongation+upsetting FM method for elongation" is adopted to achieve forging looseness and porosity, improve stress and inclusion distribution in the core of the steel ingot, and prevent the formation of new crack sources.