Failure Analysis of High Strength Galvanized Bolts Used in Steel Towers
Jose Alberto Álvarez,
Roberto Lacalle,
Borja Arroyo,
Sergio Cicero,
Federico Gutiérrez-Solana
Affiliations
Jose Alberto Álvarez
LADICIM (Laboratory of Materials Science and Engineering), University of Cantabria, ETS. Ingenieros de Caminos, Av/Los Castros 44, Santander 39005, Spain
Roberto Lacalle
LADICIM (Laboratory of Materials Science and Engineering), University of Cantabria, ETS. Ingenieros de Caminos, Av/Los Castros 44, Santander 39005, Spain
Borja Arroyo
LADICIM (Laboratory of Materials Science and Engineering), University of Cantabria, ETS. Ingenieros de Caminos, Av/Los Castros 44, Santander 39005, Spain
Sergio Cicero
LADICIM (Laboratory of Materials Science and Engineering), University of Cantabria, ETS. Ingenieros de Caminos, Av/Los Castros 44, Santander 39005, Spain
Federico Gutiérrez-Solana
LADICIM (Laboratory of Materials Science and Engineering), University of Cantabria, ETS. Ingenieros de Caminos, Av/Los Castros 44, Santander 39005, Spain
This paper analyses the failure of three bolts used in the structural connections of a number of steel towers located in northern Europe. The analysis comprises optical and scanning electron microscopy, microstructural and hardness analysis, mechanical testing and structural integrity assessments. The three bolts present very similar failure processes, with a circumferential external crack that led to the final failure. The morphology of the crack propagation is typical of Hydrogen-Induced Stress Corrosion Cracking (HISCC), with mixed intergranular-transgranular micromechanisms, tearing processes and secondary cracking. The cracks then grew subcritically until they reached their critical size. Quench cracking or fatigue processes have been ruled out.
