부산대학교 도서관

High-strength 690-MPa steel was prepared using a wire + arc additive manufacturing (WAAM) technology. The phase composition, microstructure, and crystal structure of highstrength 690-MPa steel samples were analysed, and the results show that a sample prepared using WAAM technology achieves a good formation quality. The metallographic structure was mainly acicular ferrite, massive ferrite, and granular bainite. The microhardness distribution of the vertical and horizontal sections of the samples is uniform. Excellent mechanical properties of the specimen were shown, including a horizontal yield strength of 536 MPa, a tensile strength of 760 MPa, an elongation of 23.5%, a Charpy impact value of 70 J at -508C, a vertical yield strength of 486 MPa, a tensile strength of 758 MPa, an elongation of 21.5%, and a Charpy impact value of 51 J at -508C.