Effect of Continuous and Pulsed Current on the Metallurgical and Mechanical Properties of Gas Tungsten Arc Welded AISI 4340 Aeronautical and AISI 304 L Austenitic Stainless Steel Dissimilar Joints

Abstract

In this research work, the weldability of low alloyed AISI 4340 aeronautical steel and AISI 304L austenitic stainless steel joined by continuous current (CC) and pulsed current (PC) gas tungsten arc welding (GTAW) techniques, using ER309L and ERNiCr-3 filler metals was investigated. The main focus of the study involves the investigation on the effect of continuous and pulsed current mode of GTA welding process on the metallurgical and mechanical properties of these dissimilar weldments. Microstructure studies revealed the formation of different zones across the weldments, vis-à-vis martensite at the HAZ of AISI 4340, vermicular δ -ferrite /ferrite stringers at the HAZ of AISI 304L, pearlite colonies at the parent metal of AISI 4340 and equi-axed cellular and/or columnar dendrites at the weld zone. Tensile results showed that current pulsing accrued better tensile properties. The structure -property relationships of these weldments were established based on the current modes employed by utilizing combined techniques of optical microscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS).

Dissimilar friction stir welding of AISI 430 ferritic and AISI 304L austenitic stainless steels

“…Welding of dissimilar materials is conducted frequently in different fields of industry such as power plants [1], chemical and petrochemical industries [2], as well as for nuclear and marine applications [3] to meet the accrued demand from the design and service conditions. This kind of joining is beneficial due to both technical and economic reasons which effectively utilizes the special properties including physical and mechanical of each individual materials [4]. In this regard, some industrial applications need the joining of austenitic stainless steels (ASSs) to ferritic stainless steels (FSSs) [5].…”

Potentiodynamic corrosion studies on laser beam welded austenitic stainless steel AISI 321

“…The weld bead is very narrow in the case of the LBW ranging from min 0.5 mm in the root region to maximum of 1 mm in the cap region. This when welded in the conventional welding with a filler wire shall have produced a wider weld bead [12,13]. Also, there is no trace of heat affected zone adjacent to the weld interface.…”

Effect of Pulsed Current Gas Tungsten Arc Process on the Dissimilar Weldments between Nickel-based Superalloy/Austenitic Stainless Steel

“…24,39) However, the precipitation of harmful deleterious tetragonal closed packed phases (TCP) such as sigma, P and μ were found to be totally absent due to controlled heat input and proper choice of filler material as confirmed by SEM-EDS analysis. The complete elimination of harmful secondary phase(s) in Superalloys 8,24) and dissimilar combination of 4 340 Alloy steel/Grade 304 L 28) was also reported on switching over from conventional GTAW to PCGTAW. The reason for this could be explained in terms of the theory of distribution coefficient (k) which was applied to quantify the propensity to micro-segregation of different alloying elements during cooling of the welds.…”

“…They concluded that the best performance could be achieved by employing ERNiCu-7 filler in combination with PCGTAW. Arivarasu et al 28) suggested employing PCGTAW technique for dissimilar joining of 4 340 Alloy steel/Grade 304 L as it provides controlled heat input which reduces the width of HAZ and secondary phase formation. Furthermore, R. Neissi et al 29) evaluated the quality of dissimilar joints between 2205 duplex stainless steel (DSS) to Grade 316 L weldments by employing both pulsed and continuous current mode.…”