Wire laser metal deposition of 22% Cr duplex stainless steel: as-deposited and heat-treated microstructure and mechanical properties

Abstract

Duplex stainless steel (DSS) blocks with dimensions of 150 × 70x30 mm3 were fabricated by Laser Metal Deposition with Wire (LMDw). Implementation of a programmable logic control system and the hot-wire technology provided a stable and consistent process producing high-quality and virtually defect-free deposits. Microstructure and mechanical properties were studied for as-deposited (AD) material and when heat-treated (HT) for 1 h at 1100 °C. The AD microstructure was inhomogeneous with highly ferritic areas with nitrides and austenitic regions with fine secondary austenite occurring in a periodic manner. Heat treatment produced a homogenized microstructure, free from nitrides and fine secondary austenite, with balanced ferrite and austenite fractions. Although some nitrogen was lost during LMDw, heat treatment or reheating by subsequent passes in AD allowed the formation of about 50% austenite. Mechanical properties fulfilled common requirements on strength and toughness in both as-deposited and heat-treated conditions achieving the highest strength in AD condition and best toughness and ductility in HT condition. Epitaxial ferrite growth, giving elongated grains along the build direction, resulted in somewhat higher toughness in both AD and HT conditions when cracks propagated perpendicular to the build direction. It was concluded that high-quality components can be produced by LMDw and that deposits can be used in either AD or HT conditions. The findings of this research provide valuable input for the fabrication of high-performance DSS AM components. Graphical Abstract

The effects of laser wire directed energy deposition processing parameters on the properties of 309L stainless steel

“…The general microstructure of the test cubes was that of ferrite on austenite matrix. The ferrite had columnar dendrites with elongated morphology growing in the direction of maximum heat input, it was also observed that the microstructure was refined in between the successive layers due to high cooling rates [12,13].The microstructure was heterogenous from layer to layer due to the high heat input and high solidification rates that occurs during additive manufacturing processes [2,14]. The microstructures of the test sample fabricated at 700W and 900W revealed lack of fusion defects this was due to insufficient penetration of the molten pool of the upper layer into the subsequent layer.…”

“…The molten pool is created in which the previously deposited layer and the wire feedstock melts in the vicinity of the thermal energy focused area. This process is repeated until the required 3 dimensional part is built [1,2]. Coaxial wire-directed energy deposition (DED) machines are a recent development that feed wire orthogonal to the substrate, enabling uniform processing from any direction of motion [3,4].…”

Study of Electroless Nickel Plating on Super Duplex Stainless Steel for Lithium-Ion Battery Cases: Electrochemical Behaviour and Effects of Plating Time

“…The material was subjected to heat treatment, including casting, solution heat treatment, and heat treatment, for secondary-phase precipitation [19,28,45,46,52]. A schematic of the heat treatment conditions is shown in Figure 1.…”

Effects of Passivation with Cu and W on the Corrosion Properties of Super Duplex Stainless Steel PRE 42

“…Among the various types of steel, stainless steel is particularly interesting because of its remarkable corrosion resistance and strength [1][2][3][4][5], whereas duplex stainless steels (DSSs) exhibit excellent strength and corrosion resistance owing to their high Cr and Ni contents [6][7][8]. DSSs are graded based on their pitting resistance equivalents (PRE = wt.% Metals 2024, 14, 284 2 of 13 Cr + 3.3 wt.% Mo + 16 wt.% N), with super grade DSSs (SDSSs) having PREs of 40-50 [9][10][11].…”