Nanoscale Surface Analysis on Second Generation Advanced High Strength Steel after Hot Dip Galvanizing

TL;DR

This study investigates the nanoscopic surface chemistry of second-generation advanced high strength steel after hot dip galvanizing, revealing surface oxide structures and composition to improve corrosion protection strategies.

Contribution

It provides detailed nanoscopic analysis of surface oxides on nano-TWIP steel post-galvanizing, aiding in understanding and enhancing galvanic protection.

Findings

Manganese segregation leads to oxide formation affecting coating quality

Surface oxides characterized by advanced spectroscopic methods

Insights into surface processes to improve corrosion resistance

Abstract

Second Generation advanced high strength steel is the material of choice for modern automotive structural parts because of its outstanding maximal elongation and tensile strength. Nonetheless there is still a lack of corrosion protection for this material due to the fact that cost efficient hot dip galvanizing can not be applied. The reason for the insufficient coatability with zinc is found in the segregation of manganese to the surface during annealing and the formation of manganese oxides prior coating. This work analyses the structure and chemical composition of the surface oxides on so called nano-TWIP (twinning induced plasticity) steel on the nanoscopic scale after hot dip galvanizing in a simulator with employed analytical methods comprising scanning Auger electron spectroscopy (SAES), energy dispersive x-ray spectroscopy (EDX), and focused ion beam (FIB) for cross section preparation. By the combination of these methods it was possible to obtain detailed chemical images serving a better understanding which processes exactly occur on the surface of this novel kind of steel and how to promote in the future for this material system galvanic protection.