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1. (WO2013117273) PROCESS FOR THE HOT DIP COATING OF A FLAT STEEL PRODUCT

Pub. No.:    WO/2013/117273    International Application No.:    PCT/EP2012/075402
Publication Date: Fri Aug 16 01:59:59 CEST 2013 International Filing Date: Fri Dec 14 00:59:59 CET 2012
IPC: C23C 2/02
Applicants: THYSSENKRUPP STEEL EUROPE AG
OUTOKUMPU NIROSTA GMBH
Inventors: BLUMENAU, Marc
GUSEK, Christopher
JINDRA, Fred
SCHÖNENBERG, Rudolf
KRAUTSCHICK, Hans-Joachim
Title: PROCESS FOR THE HOT DIP COATING OF A FLAT STEEL PRODUCT
Abstract:
The invention provides a process which enables the process-stable hot dip upgrading of Ni-alloyed flat steel products (S) to be carried out cost-effectively and with efficient use of resources. For this purpose, the process comprises the following working steps: a) provision of a flat steel product (S) composed of a steel containing ≥ 2.0% by weight of Ni and ≥ 5.0% by weight of Cr; b) heating of the flat steel product (S) within 1-30 s to a hold temperature of 700-1100°C under a heating atmosphere (Atm1) containing N2 and optionally (in % by volume) 1-50% of H2, 0.1-2.0% of CO and 5.0-15.0% of CO2 and having a dew point TP1 of from -15 to +30°C; c) holding of the flat steel product (S) at the hold temperature for a hold time of 10-120 s under a hold atmosphere (Atm2) consisting of N2 and (in % by volume) 1.0-50.0% of H2 and ≤ 1.0% of O2 and having a dew point TP2 of from -30 to 0°C; d) cooling of the flat steel product (S) from the hold temperature to a strip entry temperature of 430-800°C; e) passing the flat steel product (S) through a blowpipe zone (6) in which an inert or reducing blowpipe atmosphere (Atm4) prevails and passing the flat steel product through a melt bath (B); where TP1 > TP2 > TP4.