Effect of cold rolling on microstructure, corrosion and electrochemical response of the lean duplex stainless steel LDX 2101® by a correlative EBSD–SKPFM investigation

Abstract

AbstractThis study elucidates the effect of cold rolling on the microstructure, corrosion and electrochemical response of the lean duplex stainless steel LDX 2101®. With thickness reductions of 0%, 20% and 40%, three different specimens are investigated in terms of microstructure (electron backscattered diffraction [EBSD] and energy‐dispersive X‐ray spectroscopy [EDS]), corrosion properties (ASTM G150, ASTM G61 and field testing), passive film properties (X‐ray photoelectron spectroscopy) and electrochemical response (scanning Kelvin probe force microscopy [SKPFM]). It is shown that deformation of LDX 2101 leads to changes in the microstructure such as mechanical twinning and martensite formation. The combination of EBSD, EDS and SKPFM maps shows that the work function is clearly dependent on composition, deformation and local misorientation, but not on the crystallographic orientation of the grains in the microstructure. Zones with low work function are seen to have the highest pitting susceptibility, which includes deformed ferritic, martensitic phase and areas with a high concentration of dislocations such as grain boundaries and mechanical twins. The overall conclusion is that cold deformation up to a 40% thickness reduction has a significant influence on the microstructure, but a small impact on the corrosion resistance of LDX 2101.