On the influence of cold work on the oxidation of some stainless steels

Abstract

Oxidation experiments, performed by means of light interference microscopy, give information of the initial oxidation on a microscopic scale. A thin oxide layer on the substrate gives rise to an interference colour, which is directly correlated to the thickness of this layer. It is shown that not all stainless steels react in the same way to the same pretreatments. The oxidation behaviour of drawn AISI 304 and AISI 321 is completely different from that of Incoloy 800 H, while the undeformed and recrystallized samples all show the same oxidation behaviour. It is suggested that this behaviour of AISI 304 and AISI 321, is caused by the formation of a' martensite in the deformed austenitic matrix.Oxidationsversuche in Verbindung mit optischer Interferenzmikroskopie liefern Aussagen iiber die Anfangsstadien der Oxidation im Mikrobereich. Die auf dem Substrat entstehende diinne Oxidschicht fiihrt zum Auftreten einer Interferenzfarbe, die direkt mit der Dicke dieser Schicht korrelierbar ist. Es wird gezeigt, dal3 das Verhalten der nichtrostenden Stahle auch bei gleicher Vorbehandlung verschieden ist. So ist das Oxidationsverhalten von gezogenem Stahl AISI 304 und 321 vollkommen anders als das von Incoloy 800 H, wahrend unverformte und rekristallisierte Proben sich gleich verhalten. Dieses Verhalten der Stahle 304 und 321 ist wahrscheinlich der Bildung von a'-Martensit in der verformten austenitischen Matrix zuzuschreiben.

On the kinetics of oxidation of austenitic stainless steels AISI 304 and incoloy 800H

“…For Incoloy 800H a decrease in oxidation resistance with increasing cold work has been reported [22]. However, this influence has not been seen in this study -probably due to an increased number of defects created by the bombardment procedure.…”

“…Due to cold work a phase transformation occurs in which some martensite formation takes place in the austenitic grains. The grain boundaries between the austenite and martensite grains show a very high diffusivity for Cr and Fe [21], explaining the increase of the oxidation resistance of AISI 304 as a result of cold work [1, 2,22].…”

Multi-scale characterization of stress corrosion cracking of cold-worked stainless steels and the influence of Cr content

“…Cold work, in particular, was found to be beneficial in the long term, increasing oxidation resistance in 304 stainless steels [26]. Langevoort's work showed a small influence of cold work on the oxidation behaviour of 304 stainless steel under atmospheric and ultrahigh-vacuum conditions [25][26][27].…”

On the influence of cold work on the oxidation behavior of some austenitic stainless steels: High temperature oxidation

“…Langevoort et al 5 explained their results from optical microscopic measurements of AISI 304 at temperatures of 770-970 K with the formation of an a' martensite structure within the austenite matrix. This martensite structure was found to exhibit a high rate of diffusion for chromium, 7 which will lead to a very fast initial and a very slow subsequent oxidation, due to a protective Cr203 oxide layer.…”

“…Stevens 4 observed that annealed specimens showed a better oxidation resistance than cold worked ones. Langevoort et aL 5 reported an increase in oxidation resistance of AISI 304 and 321 in the temperature range 800-1000 K, but a decrease in oxidation resistance of Incoloy 800H after cold work. Stokkers et aL 6 observed an increase in oxidation rate after ion bombardment of stainless steel AISI 314.…”