forging work roll

Forged steel cold rolling rolls commonly use electric slag steel to manufacture roll blanks; Steel ingots are usually treated with high-temperature diffusion to improve the uniformity of the chemical composition of the rolling billet; The roller blank is deformed by forging, and the material has good density; After forging the roll blank, normalizing treatment is carried out to eliminate secondary network carbides, and spheroidization annealing treatment is performed to prepare the microstructure for the subsequent quenching and tempering treatment; Perform hydrogen expansion annealing to prevent the formation of white spots.

Prior to roll quenching and tempering, appropriate heat treatment processes can improve the grass-like echo defects of roll blanks. Aiming at the grass-like echo defects detected by ultrasonic testing in 70Cr5Mo steel roll blanks, this paper adopts post-forging heat treatment processes such as normalizing and spheroidizing annealing to refine the microstructure morphology of 70Cr5Mo steel blanks, obtain favorable microstructural features, and reduce or eliminate grass-like echoes in the blanks, so as to ensure no adverse effects on inspection and service performance.

The heat treatment process of forged steel cold rolling rolls mainly includes post forging heat treatment, overall quenching and tempering treatment of the roll, deep quenching and tempering treatment of the roll body. Some cold rolling work rolls also require deep cryogenic treatment to increase the depth of the quenching layer and reduce the residual austenite content. Among them, post forging heat treatment, as a heat treatment process for roll forging, includes forms such as normalizing and spheroidizing annealing, mainly used to improve the matrix structure, eliminate stress, and improve machining and cutting performance. The overall quenching and tempering treatment of the rolling mill includes quenching and high-temperature tempering. After quenching and tempering treatment, the rolling mill substrate has good strength, toughness, plasticity, and mechanical processing properties.

This article introduces the key points of MC5D roll billet manufacturing technology. Through the reasonable application of forging process and high-temperature diffusion technology, the original segregation of roll billet is improved, liquid precipitation carbonization is eliminated, and the density of roll billet is increased to achieve high-quality roll billet quality requirements, while effectively reducing production costs..

The fracture of the 9Cr2Mo steel cold rolling roll is classified as hydrogen embrittlement fracture, with the crack initiation site located at the circular spots inside the roll where hydrogen accumulates. High hydrogen content and large quenching stress caused by delayed tempering are the main causes of hydrogen embrittlement fracture of the roll, while severe dendrite segregation and abundant inclusions accelerate the fracture. The recommendations are as follows:① Improve metallurgical quality to reduce the content of inclusions and the degree of segregation in the steel;② Increase the forging ratio to avoid dendrite segregation in the material;③ Prolong the hydrogen diffusion time to reduce the hydrogen content of the roll;④ Conduct tempering in a timely manner to reduce the quenching stress of the cold rolling roll.