Fatigue behavior of ASTM A131 EH36 steel samples additively manufactured with selective laser melting

Publication date: Available online 4 February 2020Source: Materials Science and Engineering: AAuthor(s): Jingjing Wang, Meng Zhang, Xipeng Tan, Tong Liu, Guijun Bi, Hua Li, Shu Beng Tor, Erjia LiuAbstractBy tuning the process parameters mainly scanning speed ASTM A131 EH36 steel samples with high strength (1000 MPa) and fair ductility (10%) were additively manufactured through a selective laser melting process. A dual phase structure consisting of recrystallized fine ferrite and highly tempered martensite (<30%) resulted from a lower laser scanning speed of 100 mm/s. The higher heat input incurred with lower scanning speed improved the densification of the built samples, which was beneficial for achieving enhanced mechanical properties. Fatigue life cycles of the samples built at lower scanning speeds excelled those built at higher scanning speeds. Porosity induced failure was found to dominate the high cycle fatigue failure for all the samples printed, which was attributed to the ubiquitous distribution of the pores in large quantity and size with complex shapes. Grain orientation in the horizontally built samples favored crack propagation in the early stage, which was believed to contribute to the lowered fatigue limit and life. The stable crack propagation and fast fracture regime were characterized by tearing topology surface and dimples, respectively, for the samples. The fatigue behavior of the SLMed EH36 steel samples was correlated to their microstructure as w...
Source: Materials Science and Engineering: A - Category: Materials Science Source Type: research