Experimental investigation of mechanical properties of corroded cold-formed steels

Mechanical properties of corroded cold-formed steels were experimentally investigated. Flat and corner coupon specimens with different sectional loss ratio ranged approximately from 0 to 0.384 were subjected to monotonic tensile test to determine stress-strain curves and were measured by non-contact surface topography instrument ST400 3D to obtain the surface morphology. A method for calculating the minimum section area of flat and corner coupon specimens was established based on the surface morphology data. Finally, the failure mode and degradation laws of mechanical properties were analyzed. Results indicated that the fracture morphology is shear type for flat coupon specimens at low sectional loss ratio but only for non-corroded corner coupon specimens. The reduction in the elastic modulus of corner coupon specimens is greater than that of flat coupon specimens. With regard to flat coupon specimens, the degradation ratio of elongation significantly decreases at low sectional loss ratio and then tends to be slowed down with the increasing sectional loss ratio. But the elongation of corner coupon specimens decreases linearly with sectional loss ratio. Moreover, flat coupon specimens lost elastic strain energy more rapidly than corner coupon specimens. Thereafter, a stress-strain curve model far corroded cold-formed steels with different corrosion damage has been proposed. (C) 2019 Elsevier Ltd. All rights reserved.