Corrosion resistance of W600 hot work tool steel in artificial rainwater and 3.5 % NaCl solution

Sandra Brajčinović, Anita Begić Hadžipašić, Jožef Medved and Franjo Kozina

DOI: https://doi.org/10.64486/m.65.4.13
Online publication date: April 29, 2026

Abstract: This paper studied the corrosion resistance of W600 tool steel in artificial rainwater and 3.5 % NaCl solution. The equilibrium phase diagram was determined from the material’s chemical composition, with calculations and thermodynamic simulations carried out using Thermo-Calc software, enabling accurate prediction of stable phases as a function of temperature and composition. According to the obtained projections, the solidification and precipitation of individual phases at characteristic temperatures was read. Following the completion of the electro-chemical measurements, insight into the corrosion behavior of the tested sample was provided. Electrochemical tests showed a decrease in charge transfer re-sistance and an increased corrosion rate in the 3.5 % NaCl solution, indicating inadequate resistance in a chloride-containing solution, attributed to the formation of a thin oxide layer caused by the attack of chloride ions from the solution. Metallographic analysis confirmed the occurrence of slowly progressing pit-ting corrosion in chloride solution, while no significant changes were observed after testing in artificial rainwater. The lower rate of pitting corrosion was at-tributed to the martensitic microstructure with fine needle-like morphology with uniformly distributed carbides in the W600 tool steel. Such investigations are essential for understanding material behavior in aggressive environments and for reliably predicting its durability in real applications.

Keywords: hot work tool steel; corrosion resistance; corrosion parameters; impedance; micro-structure

This article is published online first and will appear in Metalurgija, Vol. 65, Issue 4 (2026).