Duplex Stainless Steel Welds Research Articles

Experimental investigation on dissimilar weld between super duplex stainless steel 2507 and API X70 pipeline steel

This work investigates the microstructure and mechanical properties of 2507 super duplex stainless steel and API X70 high strength low alloy steel weld joint. This joint finds application in offshore hydrocarbon drilling riser and oil–gas pipelines. Coated shielded metal arc welding electrodes have been designed and extruded on 309L filler and their performance compared with a commercial austenitic electrode E309L. Filler 309L solidifies in ferrite-austenite (F-A) mode with a resultant microstructure comprising skeletal ferrites with austenite distributed in the interdendritic region. Results of tensile and impact tests indicate that weld fabricated with laboratory-developed electrodes has higher ductility and impact energy than the commercial electrode. The tensile strength and weld hardness of commercial electrodes are superior. The laboratory-made electrode’s microhardness is lower than the commercial electrodes, making the former less prone to failure. An alternative welding electrode coating composition has been suggested through this work and found to be performing satisfactorily and comparable to the commercially available electrodes.

Comparisons of Different Oxide Fluxes in Activated Gas Tungsten Arc Welding of Duplex Stainless Steels for Improved Depth of Penetration and Pitting Corrosion Resistance

ABSTRACT The present work analyses the effect of five types of oxide fluxes – SiO2, TiO2, CrO3, MnO2 and MoO3 – on the depth of penetration and pitting corrosion behaviour of UNS S32205 duplex stainless steel produced with the activated tungsten inert gas welding (A-TIG) process. Five bead-on-plate (BoP) weld samples prepared autogenously with constant weld parameters. Depth of penetration (DP), depth-to-width (D/W) ratio and weld bead width (BW) were measured and compared with reference to the weld thermal cycle. The test results of ferrite measurement and micro-hardness were compared with normal – without flux added TIG-welded sample. Macro analysis of all samples indicates that SiO2 and TiO2 flux offer enhanced penetration depth and D/W ratio, in contrast, to use of other fluxes. Possibly, under the effect of either reversed Marangoni or arc constriction or both, however, all TIG BoP weld samples exhibited poor pitting corrosion resistance. Enhanced heat input due to flux and thus resultant unbalanced ferrite austenite proportion affected pitting corrosion resistance. ASTM A 923 microstructures did not show any presence of nitride formation. Results of energy-dispersive X-ray spectroscopy and scanning electron microscopy analysis of corrosion pits showed no abnormality with the chemistry of standard 2205 DSS.

Numerical Simulation on Effect of Microstructure on Hydrogen-induced Cracking Behavior in Duplex Stainless Steel Weld Metal

Numerical Simulation on Effect of Microstructure on Hydrogen-induced Cracking Behavior in Duplex Stainless Steel Weld Metal

A Pathway to Grain Structure Control of Gas Tungsten Arc Welded Duplex Stainless Steel Through Ultrasonic Vibration

A Pathway to Grain Structure Control of Gas Tungsten Arc Welded Duplex Stainless Steel Through Ultrasonic Vibration

Electron beam welding of 2205 duplex stainless steel using pre-placed nickel-based filler material

Duplex stainless steels are commonly used in the chemical as well as in the oil and gas industry due to their excellent mechanical properties and corrosion resistance. In this research, electron beam welded duplex stainless steel joints were investigated regarding their microstructure, mechanical and corrosion properties. Since the balance between austenite and ferrite is determined by the cooling rate and the chemical composition, a pre-placed nickel-based filler material was added to the weld joint in order to promote the austenite formation, which is suppressed by the rapid cooling. This is a common phenomenon in power beam welding processes. A suitable weld geometry was achieved by oscillating and defocusing the electron beam. Thereby, the process tolerates the diverse disturbances resulting from the production as well as an unexpected occurrence of a non-zero gap size. Using a nickel-based filler wire, the welds show an excellent austenite-ferrite balance, but with heterogeneous distribution over depth due to the insufficient dilution of filler wire and base material. As a result of a balanced microstructure, the post-welding heat treatment may become necessary solely in exceptional cases. The measured values of tensile strength as well as the impact energy meet all the requirements of the EN 10088-2 and EN ISO 17781, respectively. Furthermore, the critical pitting temperature values measured in the various regions of the seam are lower compared to the base material, although, they are above of the acceptance value according to EN ISO 17781.

Laser dissimilar welding of CoCrFeMnNi-high entropy alloy and duplex stainless steel

High entropy alloys (HEAs) have superior mechanical properties that have enabled them to be used as structural materials in nuclear and aerospace applications. As a dissimilar joint design is required for these applications, we created a dissimilar joint between CoCrFeMnNi-HEA and duplex stainless steel (DSS) through laser beam welding; a technique capable of producing a sound joint between the two materials. Microstructure examination using SEM/EBSD/XRD analysis revealed that the weld metal (WM) exhibits an FCC phase regardless of the postweld heat treatment (PWHT) temperature (800 and 1000 °C) without forming detrimental intermetallic compounds or microsegregation. The heat-affected zone of the CoCrFeMnNi-HEA showed CrMn oxide inclusions while that of the DSS showed no inclusions. Moreover, a lower hardness was recorded by the WM compared to the base metal after welding. After PWHT, the hardness of the WM, CoCrFeMnNi-HEA, and DSS decreased with an increase in the PWHT temperature. However, the decrease in the hardness of the HEA was more significant than in the WM and DSS. The cause for this reduction in hardness was attributed to recrystallization and grain growth. In addition, a strength of 584 MPa with low ductility was recorded after welding. The obtained strength was lower than that of the BMs, but comparable to that of the welded CoCrFeMnNi-HEA. The application of PWHT resulted in over a 20% increment in ductility, with only a marginal reduction in strength. The deformation mechanism in the as-weld joint was mainly dominated by dislocation while that for the PWHT joint was twinning. We propose laser beam offset welding as a technique to improve the mechanical properties of the dissimilar joint, which will be the subject of future studies.

PENGELASAN DISIMILAR MATERIAL (DUPLEX STAINLESS STEEL) 2205 DAN (HIGH STRENGTH STEEL) GRADE VL D36 UNTUK KAPAL OIL TANKER

The choice of Duplex Stainless Steel material for oil tanker ship construction is very appropriate because in addition to having good mechanical properties (high tensile and yield strength and toughness) as a ship construction structure, it is also resistant to loads of highly corrosive liquid chemicals. Unlike Mild Steel or Duplex Stainless Steel A, welding and treating Duplex Stainless Steel requires very strict procedures and care must be taken. The choice of welding process, namely a combination of (Flux Cored Arc Welding) and SAW (Submerged Arc Welding) is a welding process that is very suitable for welding ship construction. The welding process is categorized as a semi-automatic and automatic welding process that can increase productivity while speeding up welding work. This paper illustrates the welding of two materials with different specifications, namely Duplex Stainless Steel 2205 plate material and VL D36 plate material, along with practical instructions for welding it up to the things that must be considered regarding the handling procedure. In welding Duplex Stainless Steel 2205 plate material it is very important to keep the heat input in the range of 0.5-2.5 kj / mm.

Effects of nitrogen element on microstructure and pitting corrosion resistance of duplex stainless steel welded joints

The microstructure, element distribution and pitting corrosion resistance of Gas Tungsten arc welding (GTAW) duplex stainless steel welded joints under 100% argon (Ar) and 98% Ar + 2% nitrogen (N2) shielding gas were studied by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and electrochemical corrosion methods. These results show that the addition of N2 to the shielding gas promotes the formation of austenite (γ) phase in the weld joint. Also, the austenite phase distribution is dendritic and the ferrite (δ) and austenite phases in the heat-affected zone are no longer banded structures. Moreover, the austenite phase in the welded joint is enriched in nickel (Ni) and nitrogen (N) elements, while the ferrite phase is enriched in chromium (Cr) and molybdenum (Mo) elements. The pitting corrosion index (PREN) of the austenite/ferrite (δ/α) phase boundary is lower than that of δ and γ phases, which leads to their preferential corrosion. The appearance of chromium nitride (Cr2N) decreases the corrosion resistance of the weld seam and the heat affected zone. N2 in the 98% Ar + 2% N2 shielding gas can restrain Cr2N precipitation, increase the pitting corrosion index of secondary austenite structure (γ 2), and improve the pitting corrosion resistance of welded joints.

Corrosion study on AA-TIG welding of duplex stainless steel

Abstract Duplex Stainless steel composition has high amounts of Cr, Ni, Mo and Fe content. Due to the high chromium content passive layer of chromium precipitate is formed on the surface of the material which resists the corrosion in the metal. Duplex Stainless steel (DSS) has good weldability and formability. Based on previous Investigations found through various literatures there is no detailed investigation was carried out on the corrosion behaviour of Automated Autogenous Tungsten Inert Gas (AA-TIG) Welding on Duplex stainless steel. To study the corrosion behaviour of Duplex Stainless Steel, This investigation was carried out in Sodium chloride (NaCl) solution environment. The main objective is to study the corrosion behaviour of the welded material by using PARSTAT 2273. To study the electrochemical impedance technique was chosen to test the AA-TIG welded DSS 2205.

Optimization of process parameters of TIG welding of duplex stainless steel without filler rod by grey-Taguchi method

Input parameters of welding have played an important role in producing the quality of welding joint. Welding quality has been improved using proper process parameters with sound knowledge base. Current, welding speed and the shielding gas flow rate have been used as the most important influencing parameters of Tungsten Inert Gas (TIG) welding on Duplex Stainless Steel (DSS). In the present work, multi-objective optimization of TIG welding process parameters of Duplex Stainless Steel - ASTM/UNS 2205 has been determined. These welding process parameters have been optimized to achieve the required quality of DSS welding joints. The quality of the TIG welding on DSS has been evaluated in term of tensile test. The grey-based Taguchi technique has been used to solve this multi- optimization problem. Analysis of Variance (ANOVA) has been applied to evaluate the significanc e of the individual factors on desired results which are ultimate tensile strength, yield strength and percentage of elongation. Additional confirmatory experiment has been done to verify the optimal results. The application possibilities of the grey-based Taguchi method for incessant development of welding quality of DSS in many fields, like chemical industries, oil refineries, gas manufacturing industries etc. have been shown by this work.

Parametric optimization of TIG welding of duplex stainless steel without filler rod by PCA method

The weld quality is mostly depended on the welding input factors. Welding quality is controlled by appropriately controlling the using process factors with sound knowledge base. The major influencing Tungsten Inert Gas (TIG) welding parameters are welding current, gas flow rate and speed of the welding. Controlling these parameters, the quality of the Duplex Stainless Steel (DSS) welding joints are improved. These welding process parameters are optimized to achieve the better quality of DSS welding joints. Here, the Principal Component Analysis (PCA) method and concept of Taguchi’s signal to noise ratio (S/N) are used to optimize the above TIG welding process parameters of UNS 2205 DSS. The quality of the TIG welding of DSS has been evaluated in term of tensile test. Statistical tool like Analysis of Variance (ANOVA) is applied to evaluate the significance of the individual factors on the desired responses like ultimate tensile strength, yield strength etc. The optimal result is verified by the additional experiment. This result shows the application possibility of the PCA method for incessant development of welding quality of DSS in many fields, like chemical industries, oil & gas refineries, manufacturing industries etc.

Weldability of duplex stainless steels- A review

Duplex stainless steel finds widespread use in various sectors of manufacturing and related fields. It has many advantages due to its distinctive structural combination of austenite and ferrite grains. It is the need of the current generation due to its better corrosive resistance over high production austenitic stainless steels. This paper reviews the weldability of duplex stainless steels, mentions the reason behind the need for duplex stainless steels and describes how it came into existence. The transformations in the heat-affected zones during the welding of duplex stainless steels have also been covered in this paper. The formation, microstructure and changes in high temperature and low temperature heat-affected zones have been reviewed in extensive detail. The effects of cooling rate on austenite formation has been briefly discussed. A comparison of weldability between austenitic and duplex stainless steel is also given. Finally, the paper reviews the applications of the various grades of duplex stainless steel in a variety of industries like chemical, paper and power generation and discusses the future scope of duplex stainless steel in various industrial sectors.

Study on Effect of Microstructure on Hydrogen Cracking in Duplex Stainless Steel Welds

Study on Effect of Microstructure on Hydrogen Cracking in Duplex Stainless Steel Welds

WITHDRAWN: WITHDRAWN: Duplex stainless steel welding microstructures have been engineered for thermal welding cycles & nitrogen (N) gas protection

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Relationship between pitting corrosion resistance and Cr-depleted zone in duplex stainless steel weld metals

Relationship between pitting corrosion resistance and Cr-depleted zone in duplex stainless steel weld metals

Prediction of reversible α⇄γ phase transformation in HAZ of multi-pass welded duplex stainless steel by the phase-field method

Prediction of reversible α⇄γ phase transformation in HAZ of multi-pass welded duplex stainless steel by the phase-field method

Investigation on microstructure and mechanical properties of double-sided synchronous TIP TIG arc butt welded duplex stainless steel

Double-sided synchronous TIP TIG arc butt welding (DSSTTABW) is firstly carried out to join 5-mm SAF 2205 duplex stainless steel (DSS) plates without grooving. The microstructure and mechanical properties of DSSTTABW joints, including microhardness, transverse tension, and bend properties, are evaluated systematically. Results show that sound DSS joint, with excellent appearance and properties, can be obtained through the DSSTTABW process. In DSSTTABW joints, a deal of second austenite (γ2) appears in the weld metal, resulting in a slight increment of austenite volume fraction of the weld zone. Meanwhile sigma (σ) phase precipitates at the grain boundaries of delta ferrite (δ-Fe) and austenite of the weld zone. Mechanical property tests show that the DSSTTABW weldment exhibits higher tensile strength and microhardness but lower ductility compared to 2205 DSS base metal due to the existing Widmanstten-type austenite (WA) and σ phase. All weldments fracture at the weld zones in the mode of ductile. After bending tests, no surface cracks are observed on the DSSTTABW joint.

Promoting austenite formation in laser welding of duplex stainless steel\u2014impact of shielding gas and laser reheating

Avoiding low austenite fractions and nitride formation are major challenges in laser welding of duplex stainless steels (DSS). The present research aims at investigating efficient means of promoting austenite formation during autogenous laser welding of DSS without sacrificing productivity. In this study, effects of shielding gas and laser reheating were investigated in welding of 1.5-mm-thick FDX 27 (UNS S82031) DSS. Four conditions were investigated: Ar-shielded welding, N2-shielded welding, Ar-shielded welding followed by Ar-shielded laser reheating, and N2-shielded welding followed by N2-shielded laser reheating. Optical microscopy, thermodynamic calculations, and Gleeble heat treatment were performed to study the evolution of microstructure and chemical composition. The austenite fraction was 22% for Ar-shielded and 39% for N2-shielded as-welded conditions. Interestingly, laser reheating did not significantly affect the austenite fraction for Ar shielding, while the austenite fraction increased to 57% for N2-shielding. The amount of nitrides was lower in N2-shielded samples compared to in Ar-shielded samples. The same trends were also observed in the heat-affected zone. The nitrogen content of weld metals, evaluated from calculated equilibrium phase diagrams and austenite fractions after Gleeble equilibrating heat treatments at 1100 °C, was 0.16% for N2-shielded and 0.11% for Ar-shielded welds, confirming the importance of nitrogen for promoting the austenite formation during welding and especially reheating. Finally, it is recommended that combining welding with pure nitrogen as shielding gas and a laser reheating pass can significantly improve austenite formation and reduce nitride formation in DSS laser welds.

Effect of Heat Treatment on the Microstructure of Duplex Stainless Steel Welds

Abstract Duplex stainless steels (DSS) are gaining in popularity due to their characteristic features, excellent mechanical properties, and corrosion resistance. The microstructure of DSSs consists of ferrite up to 50 %, and the rest is built up from austenite. The ferritic microstructure can cause chromium-nitride precipitation because the nitrogen solubility in the ferrite phase is very low below 700 °C. Our research showed that electrochemical etching is an acceptable process for revealing chromium-nitrides. Additionally, our research points out that chromium-nitride acts as a secondary austenite nucleation site.

Explosive welding of Al alloys and high strength duplex stainless steel by controlling energetic conditions

Abstract In this study, Al alloys and high strength duplex stainless steel plates were welded using explosive welding technology. Compared with the direct welding method, the use of an interlayer can reduce kinetic energy dissipated during the welding of dissimilar metals, which reduce the thickness of excessive melting layer to achieve high-quality welding. Different interface morphologies were observed under different welding parameters. In particular, a flat welding interface was observed which differed from conventional explosive welding, when the velocity of the flyer plate was relatively less. The tensile shear tests and bending tests demonstrated that the welding strength was high when high-quality welding was achieved. The smoothed particle hydrodynamics (SPH) numerical model was used to simulate the welding process, and the simulated interface morphologies were consistent with the experimental results. The jet velocity, temperature, and strain near the interface and the velocity and collision angle of the interlayer at the collision point were calculated using the numerical simulations. As per the discussion based on the weldability window, the difficulty of achieving direct welding between Al alloys and duplex stainless steel was demonstrated. Using weldability window to analysis tri-metallic joints, the analysis revealed why using an interlayer can make the welding easily. Further, a method to realize interlayer welding is presented.