13-14 June 2022
Schönbrunn Palace/Apothekertrakt
Europe/Vienna timezone

ON GRAIN BOUNDARY TOPOGRAPHY AND SURFACE REACTIVITY DURING HOT-DIP GALVANISING

14 Jun 2022, 08:00
1h
Schönbrunn Palace/Apothekertrakt

Schönbrunn Palace/Apothekertrakt

Apothekertrakt Schönbrunn, Meidlinger Tor, Grünbergstraße, 1130 Vienna

Speaker

Nils Köpper (Salzgitter Mannesmann Forschung GmbH)

Description

Under certain conditions of oxygen shortage and high temperatures as could occur after coiling a hot-rolled strip, alloying elements can diffuse and oxidise preferably along grain boundaries, causing a depletion zone of solute alloying elements in the surface near region. When oxides are present along grain boundaries, pickling can alter surface topography by selective dissolution of these oxides on the µm-scale (µ-topography).
In this lecture I would like to introduce you into the principles of grain boundary oxidation in hot strip and its influence on the subsequent processes.
This grain boundary oxidation in hot rolled state leads to surprisingly visible effects on the µ-topography before galvanising. This altered topography and the depletion of alloying elements influence diffusion properties during intercritical annealing prior to hot-dip galvanising, leading to a reduced surface segregation of alloying elements. Surfaces with altered µ-topography show lower surface segregation of alloying elements, can build more dense inhibition layers during hot-dip galvanising with the same annealing conditions, and exhibit improved coating adhesion. This effect could be helpful to enhance galvanisability of future challenging steel grades.
Furthermore, I will give a short overview of the topic “Developments in On-Line Coated Steel Measurements & Coating Analysis”. In this thematic field, I will present a selection of exciting findings on the topics of coating characterisation, surface inspection systems with deep learning and interesting analytical methods in a short overview.

Best Paper Winner Nils Köpper, Salzgitter Mannesmann Forschung GmbH, will present highlights from his Galvatech 2021 paper "ON GRAIN BOUNDARY TOPOGRAPHY AND SURFACE REACTIVITY DURING HOT-DIP GALVANISING
". Selected highlights from other Galvatech 2021 papers on advances in our understanding of coating analysis and on-line measurements will also be summarized.

Each session will start with the 20 minute lecture, followed by a 20 minute panel discussion. This will be followed by 10 minutes of general discussion and a short break before beginning the next session.

Keywords

galvanized high-strength steel, selective oxidation, hot rolled steel, inhibition layer, grain boundary oxidation, hot dip galvanizing simulator, surface reactivity, µ-topography, segregation, depletion

Primary author

Nils Köpper (Salzgitter Mannesmann Forschung GmbH)

Co-authors

Dr Friedrich Luther (Salzgitter Mannesmann Forschung GmbH) Dr Thomas Koll (SZMF)

Presentation Materials