Characterization of microstructures and mechanical properties of Inconel 617/310 stainless steel dissimilar welds

doi:10.1016/j.matchar.2011.02.003

Materials Characterization

Volume 62, Issue 4, April 2011, Pages 425-431

https://doi.org/10.1016/j.matchar.2011.02.003 Get rights and content

Abstract

The microstructure and mechanical properties of Inconel 617/310 austenitic stainless steel dissimilar welds were investigated in this work. Three types of filler materials, Inconel 617, Inconel 82 and 310 austenitic stainless steels were used to obtain dissimilar joint using the gas tungsten arc welding process. Microstructural observations showed that there was no evidence of any possible cracking in the weldments achieved by the nickel-base filler materials. The welds produced by 617 and 310 filler materials displayed the highest and the lowest ultimate tensile strength and total elongation, respectively. The impact test results indicated that all specimens exhibited ductile fracture. Among the fillers, Inconel 617 exhibited superlative fracture toughness (205 J). The mechanical properties of the Inconel 617 filler material were much better than those of other fillers.

Research Highlights

► A fine dendritic structure was seen for the Inconel 617 weld metal. ► A number of cracks were initiated when the 310 SS filler metal was used. ► All welded samples showed ductile fracture. ► The Inconel 617 filler material presents the optimum mechanical properties.

Introduction

Inconel 617 (UNS N06617: Ni–22Cr–12Co–9Mo) is primarily a solid solution nickel-base superalloy with superior engineering properties. This alloy has been widely employed in power plants, aerospace, chemical, and nuclear industries because of its exceptional properties of high temperature strength and creep resistance. In addition, this alloy is extensively used in many reducing and oxidizing environments due to its excellent hot corrosion behavior derived from the simultaneous presence of chromium, aluminum and molybdenum in the alloy composition [1], [2], [3], [4]. As Inconel 617 is a relatively expensive alloy, a cheaper material with good properties can be used in lower risk conditions to reduce material costs. AISI 310 austenitic stainless steel (SS), is a prevalent material used in high temperature applications (about 1150 °C). This alloy would be a good alternative for Inconel 617. Due to the presence of chromium, an adherent oxide layer is formed on the surface of 310 SS. This layer can protect the alloy in oxidizing conditions [5], [6]. The application of dissimilar welding processes such as gas tungsten arc welding may be inevitable to alternate Inconel 617 with AISI 310 stainless steel.

Generally, the selection of a suitable filler material in dissimilar welding is one of the most important concerns. In recent years, extensive investigations have been conducted for introducing suitable filler materials in dissimilar welding processes. Sireesha et al. [7] used four types of filler metals to joint 316LN SS and alloy 800. Their results showed that the Inconel 82/182 filler materials exhibited the best properties. Dupont et al. [8] investigated the effect of processing parameters and filler metal chemistry on the microstructure and weldability of dissimilar welds between AL-6XN super SS and two nickel-base alloys, Inconel 625, and Inconel 622. Lee et al. [9] showed that the increase of Ti in filler metal composition led to the formation of equiaxial dendrites and thereby, increased elongation in the welding of nickel-base alloy 690 to SUS 304L. Weldability and joint properties between Inconel 657 and 310 SS were investigated by Naffakh et al. [10]. They illustrated that the Inconel A (a nickel base filler metal) was the best choice among four filler metals.

Based on a literature survey, no previous work has been reported on the dissimilar welding between Inconel 617 and 310 SS. The aim of this study was to investigate the influence of filler materials in order to achieve the best mechanical properties in severe conditions.

Section snippets

Experimental Procedures

The base materials used in this work were nickel-base superalloy Inconel 617 and 310 SS under the rolled and solution annealed condition in the form of 12 mm thick plates. Three types of filler materials, Inconel 617, Inconel 82, and 310 SS were employed. The chemical compositions of the base and filler materials are given in Table 1.

The base metal plates were cut and machined to the size of 195 mm × 32 mm × 12 mm. The specimens were machined to make a single V groove butt joint configuration with 70°

Base Metal Microstructures

The microstructure of the 310 SS base metal is shown in Fig. 2. The microstructure consisted of fine equiaxed grains of austenite. Annealing twins can be observed in the austenitic matrix. There does not appear to be any delta ferrite or carbide precipitates in the microstructure due to a proper annealing treatment after cold rolling. The fully austenitic structure improves toughness and corrosion properties especially at high temperatures, but encourages the sensitivity to solidification

Conclusions

Three types of filler materials, Inconel 617, Inconel 82 and 310 austenitic stainless steels were used to obtain dissimilar Inconel 617/310 austenitic stainless joint using the gas tungsten arc welding process.

The following conclusions can be drawn from the results:

•
The weld microstructure was fully austenitic for all filler materials. A cellular structure was seen for the 310 SS, while the dendritic solidification occurred for the Inconel 617 and 82 filler metals. The microstructure of the

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Characterization of microstructures and mechanical properties of Inconel 617/310 stainless steel dissimilar welds

Abstract

Research Highlights

Introduction

Section snippets

Experimental Procedures

Base Metal Microstructures

Conclusions

Corros Sci

J Nucl Mater

J Nucl Mater

Mater Sci Eng A

Mater Charact

Inconel alloy 617—a new high temperature alloy

Methods Eng Q

Microstructure and phase stability of Inconel alloy 617

Metall Trans