Failure Case Study Series Part Two: Failure Analysis of Roller Guides in a Wire Rod Rolling Mill

The paper aims to present the root cause of failure of roller guides from the wire rod and coil rolling mill during normal operation. A comprehensive failure investigation was conducted following standard metallurgical procedures, including visual inspection, hardness testing, chemical analysis, optical microscopy, stereomicroscopy, scanning electron microscopy (SEM–EDS) characterization, and inclusion rating according to ASTM E45. The investigation concludes that the primary root cause of failure was the use of D3 tool steel, which is unsuitable for components subjected to severe thermal cycling, resulting in progressive thermal fatigue damage and eventual catastrophic fracture. Moreover, the election of D2 or other Mo-V alloyed hot‑work tool steels, combined with appropriate surface hardening, is recommended to enhance service life under rolling mill operating conditions.