The Influence of Heat Treatment Temperature on Microstructure and Corrosion Behavior of SDSS Tube

Title & Authors
The Influence of Heat Treatment Temperature on Microstructure and Corrosion Behavior of SDSS Tube
Lee, Insup; Cheon, Chang-seok; Yim, Tai-Hong; Han, Yoon-Ho; Lee, Myon-Hag;

Abstract
The aim of this paper is to determine the proper heat treatment temperature for SDSS tube production without $\small{{\sigma}}$-phase precipitation. When Mother steel tube was heat treated at $\small{800^{\circ}C}$ temperature, relatively a large amount of $\small{{\sigma}}$-phase precipitated and grain refinement of ferrite phase occurred simultaneously. However, in Pilgered and Drawn steel tubes, grain refinement of the ferrite phase did not occur and a small amount of $\small{{\sigma}}$-phase precipitated. For all three types of steel tubes, the pitting potential was reduced to 2/5 or less compared with the untreated one and corrosion also occurred in the salt spray test due to the precipitation of $\small{{\sigma}}$-phase. When heat treatment temperature was $\small{900^{\circ}C}$, grain refinement of the ferrite phase occurred and very little $\small{{\sigma}}$-phase precipitated in Pilgered and Drawn steel tubes. But when heat treatment was done at $\small{1,000^{\circ}C}$ temperature, all three types of steel tubes had a similar corrosion properties of that of untreated one and also corrosion did not occur in the salt spray test, as $\small{{\sigma}}$-phase did not precipitate. Therefore, the optimum heat treatment temperature range is determined to be more than $\small{1000^{\circ}C}$ for the SDSS at which corrosion does not occur.
Keywords
$\small{{\sigma}}$-phase precipitation;corrosion resistance;hardness;super duplex stainless steel;
Language
Korean
Cited by
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