Investigating the impact of aging on the mechanical properties of steel extracted from the hull of the Royal Canadian Navy ship Ex-HMCS Iroquois

This paper presents the research results of testing the mechanical properties and fracture surfaces of aged steel components that were extracted from the hull of the retired Royal Canadian Navy Destroyer ex-HMCS Iroquois. A study is held to investigate the aged steel of the retired ship to determine the impact of aging on the mechanical properties of the steel and identifying its capability to meet the design requirements after more than 40 years of service under various conditions. A total number of 78 specimens were subjected to mechanical and microstructural characterization. The tests included uniaxial tensile behavior analysis of 30 different specimens, Rockwell hardness testing for 8 specimens at 48 locations, fracture energy measurement through Charpy impact test of 25 specimens and fracture surface characterization of 15 distinct specimens. Average yield strength and ultimate strength for the tested aged steels were 347 MPa and 502 MPa respectively. In addition, average Rockwell hardness B was 80 HRB and ductile to brittle temperatures were calculated to be −30 °C, −20 °C and −30 °C for the plate, web and flange respectively. The results presented remarkable alignment of properties with the design requirements even after 40 years of service in various conditions. • Mechanical characterization of aged steel specimens extracted from the retired ex-HMCS Iroquois destroyer. • Mechanical Characterization included tensile tests, Charpy tests and Rockwell hardness tests. • Fracture surface morphological characterization was performed using SEM and phase identification was also applied using EDS. • Mechanical Characterization results showed that the IROQ-Steel met design requirement range after 40 years of service. • Charpy test fracture surfaces demonstrated a full transition from ductile to brittle behavior as impact test temperature decreased.