Cracking behavior and formability of Zn-Al-Mg coatings: Understanding the influence of steel substrates

•The influence of steel substrates on cracking behavior of Zn-Al-Mg coatings is elucidated using in-situ microscopy testing.•Zn-Al-Mg coatings on a high strength low-alloy (HSLA) steel exhibit higher cracking compared to those on interstitial free (IF) steel.•Discontinuous yielding by Lüders banding in the HSLA steel substrate induces heterogeneous deformation leading to coating cracking.•IF steel substrate provides a more compatible deformation with the coatings and leads to an enhanced cracking performance.•Strain mapping by digital image correlation technique is conducted on the coated steel specimens across length scales.