Development and Comparison of Quantitative Phase Analysis for Duplex Stainless Steel Weld

Abstract

In duplex stainless steels the ideally 1:1 ratio of austenite-to-ferrite phases ensures the outstanding mechanical and corrosion properties compared to other, conventional stainless steel grades. However, this phase balance can be easily shifted to a mostly austenitic or mostly ferritic microstructures, depending on the welding process and heat input. In order to determine the phase ratio, several methods are available to use, such as Feritscope measurements, ASTM E562 manual point count method (on metallographic images) or quantitative image analysis. From these methods, Feritscope measurements cannot be applied to determine phase quantification in the narrow heat affected zone of duplex stainless steel welds – because of the very limited heat input. The manual point count method is very dependent of the assessor and cannot be automated. In this paper a histogram-based image analyzing process was developed, using Beraha's etchant solution. The results were compared to Feritscope measurements and a very good correlation (R2 = 0.9995) was found. This method will give the ability to easily and automatically measure phase ratio in weld metal, heat affected zone or in subsurface regions of multi-pass welds.

Ferrite content measurement in super duplex stainless steel welds

“…[16], Varbai et al [17], and Putz et al [22], where all suggested etching followed by IA can be used to accurately measure the ferrite fraction. A suitable etching practice will minimize the required post-processing of the micrographs, otherwise a more advanced software with adjustable settings is needed to measure the ferrite fraction.…”

“…In the direct approaches, the ferrite fraction is measured using optical microscopy-based techniques such as point counting (PC) and image analysis (IA) [15][16][17] and scanning electron microscopy-based techniques such as electronbackscattered diffraction (EBSD). PC is a time-consuming technique but is manual and applicable without an image analyzing program.…”

Physical and Theoretical Modeling of the Nitrogen Content of Duplex Stainless Steel Weld Metal: Shielding Gas Composition and Heat Input Effects

“…The application of image analysis has recently been popular with researchers for DSS characterization [38,39]. A brief description of our self-developed method [40] follows. The cut weld cross-sections were prepared for standard metallography: mounted, ground to 4000 grit paper, and polished to 3 µm diamond suspension.…”

“…Next, the samples were color etched, using Berahas II etchant (85 mL H 2 O + 15 mL HCl + 1 g K 2 S 2 O 5 ). A 2 × 12 s etching cycle (total of 24 s etching time) was used, which was found to be optimal in our previous work [40]. The samples were rinsed in ethanol in between the two, 12 s, etching cycles.…”

Effect of post-weld heat treatment on microstructure and mechanical properties of DP800 and DP1200 high-strength steel butt-welded joints using diode laser beam welding

“…Advanced high-strength steels are extensively used in automotive sectors due to their extraordinary combined properties of strength, ductility, formability, high-strength to weight ratio and low CO 2 emissions [1][2][3][4][5]. Dual phase (DP) steels are a group of low-carbon micro-alloyed steels, and the term 'dual phase' indicates that the steel has two distinct phases, i.e.…”