Distortion properties in hot rolled rings

Important results from the project

The purpose of the project has been to increase the long-term predictability of distorsions that occur during hardening of steel and to reduce the rate of scrapping of hardened components. Within the framework of the project, it was specifically investigated how chemical variations within the incoming material, in the so-called center segregations, contribute to the distorsions. The goal has been to map the impact of the center segregations on distorsions and map their movement within the material during the hot working process, in this case ring rolling.

Expected long term effects

The investigation showed that center segregations clearly contribute to various types of shape changes in hardened ring gears, givan that good control of the heat treatment process is established beforehand. The carbon content in the center segregation is of particular importance. The result is valuable for being able to set requirements for the incoming material so that distorsions become more predictable in the next step.

Approach and implementation

Within the project, rod blanks were produced where the position of the center segregations were varied eccentrically and chemically. Ring gears were manufactured from these raw materials, whose distorsions were mapped after case-hardening. In addition to this, model blanks were produced to trace how the center ring was moved during the ring rolling process to the finished component. The result was compared with outcomes from a digital twin.