Measurement of Fracture Shear Stress at Coating/Substrate Interface in Hot Dip Aluminum Alloy Coated Dual-Phase Steel Sheet

摘要

This paper investigates the fracture shear stresses at coating/substrate interfaces in hot dip aluminum alloy coated dual-phase steel sheets by means of a newly designed shear test method in which shear stress is applied to the interface. The coating/substrate interfaces in the shear test specimens consisted of alloying layers: an η-Fe_2Al_5 phase layer on the steel substrate side and a θ-FeAl_3 phase layer on the coating side. A fracture occurred mainly within the η phase layer in the shear tests. The fracture shear stress values measured in 21 tests ranged from 2 to 14 MPa, and tended to increase with a decrease in the thickness of η phase layer in the shear test specimens.