Corrosion Properties Of Welded Joints Research Articles

Investigation on the pitting corrosion properties of welded joints of bimetal composite pipe

A bimetallic composite pipe butt joint was prepared by automatic gas tungsten arc welding (GTAW). The microstructure and pitting properties of the joint were investigated. The results show that the microstructure of the joint is columnar crystal, columnar dendrite, and equiaxial crystal. Mo, Nb, and Cr segregate in joint and form Laves and NbC precipitates in the interdendritic. The heat-affected zone (HAZ) becomes the preferred region for pitting due to recrystallization behavior and large and continuous Laves, this was demonstrated by both immersion corrosion and electrochemical experiments. To better understand the pitting behavior of the joint, this study discusses the mechanism of passive film rupture and pitting development, and uses electrolytic corrosion by Nital to simulate the morphology of the initial corrosion pits around the Laves phase.

Effect of low-temperature cooling on corrosion properties of laser welding Hastelloy C-276/304 stainless steel with filler wire

To suppress the weld defects and improve corrosion resistance of laser welded joints, the low-temperature cooling was applied to assist laser welding Hastelloy C-276/304 stainless steel with filler wire. And the different low-temperature cooling (-5 °C, 5 °C, 20 °C) were selected for experimental research. Results show that adding low-temperature cooling can increase the cooling rate and solidification rate of weld. And the temperature gradient grows with the increase of solidification rate near the fusion line of weld. Consequently, the content of precipitated phase decreases from 1.75% to 0.71%, reducing by nearly 59.0%. The increase of temperature gradient can reduce the unmixed zone, which decreases from 22.1 μm to 11.4 μm, reducing by nearly 48.0%. At the same time the contents of corrosion-resistant elements and the proportion of grain boundaries with small angles increase in the laser weld with low-temperature cooling. As the cooling temperature drops, the effect of microstructure optimization of weld is enhanced. Finally, the corrosion properties of welded joints are obviously improved with the temperature decrease. The corrosion potential of welded joints increases by 24.3%. The corrosion current density of welded joints reduces by 54.3%. The intergranular corrosion sensitivity of welded joints reduces by 76.5%.

A re-investigation: Effect of TIG welding parameters on microstructure, mechanical, corrosion properties of welded joints

Welding and riveting are the two fundamental joining processes for metals. Welding joints have high strength than the riveting joints. But there is a high heat-affected zone in welding. The heat-affected zone is the reason for the stress concentration and pre-mature failure. The heat-affected zone and other properties (i.e., microstructural, mechanical, and corrosion) of a welded joint depends on the welding parameters. In the present work, a re-analysis of the effect of welding parameters is done on the microstructural, mechanical, and corrosion properties of the inert tungsten gas welded materials. It was observed that the grain coarsening occurred in the heat-affected zone, while in the fusion zone, grain refinement took place. Hence, the coarsening of grains reduced the hardness and tensile strength of the material in the heat-affected zone. Heat affected zone can be reduced by reducing the current, but the reduction of current reduces the penetration.

Influence of Laser-Welding on Microstructure and Corrosion Properties of Twinning-Induced Plasticity (TWIP) Steel.

The effect of welding speed on microstructure, mechanical properties, and corrosion properties of laser-assisted welded joints of a twinning-induced plasticity (TWIP) steel was investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), electron backscattered diffraction (EBSD) analysis, electrochemical test, and micro-area scanning Kelvin probe test (SKP). The results reveal that the welded joints, with a fully austenitic structure, are obtained by laser welding. In addition, the preferred orientation of grains in fusion zone (FZ) increased with the increase of welding speed. Additionally, the coincidence site lattice (CSL) grain boundaries of FZ decreased with increasing welding speed. However, potentiodynamic polarization and SKP results demonstrated that the welding speed of 1.5 m/min renders superior corrosion resistance. It can also be inferred that the corrosion properties of the welded joints are related to the grain size and frequency of CSL grain boundary in FZ.

EFFECT OF FRICTION STIR WELDING PROCESS PARAMETERS AND POST-WELD HEAT TREATMENT ON THE CORROSION BEHAVIOUR OF AA6061-O ALUMINUM ALLOYS

The aim of the present work is to study the effect of rotation and welding speeds as well as the T4 and T6 post-weld heat treatments (PWHT) on the corrosion behavior of AA6061-O aluminum plates joined using friction stir welding (FSW). The corrosion properties of welded joints were studied by Potentiodynamic polarization and Immersion tests. The results showed that both T4 and T6 PWHT improves the corrosion resistance of stirred zones compared to base alloy. However, joints of T4 showed lower corrosion resistance compared to T6. Increasing welding speed or reducing rotation speed increased the corrosion resistance of joints.

Increased quality and welding efficiency of laser butt welding of 2205/X65 bimetallic sheets with a lagging MIG arc

2205/X65 bimetallic sheets were butt welded by a fiber laser with single pass based on flow behavior of molten pool in full penetration welding processes. Optimal welding parameters were defined based on experiments using orthogonal arrays design to ensure highest relative independence of the upper and lower fusion zones (FZ). Balance of ferrite and austenite was found to be completely disrupted. To counterbalance excess α-ferrite formed in the lower fusion zone, laser-Metal Inert Gas (MIG) tandem welding was introduced for butt welding of 2205/X65 bimetallic sheets. Microstructures and corrosion properties of welded joints were investigated using optical microscopy, scanning electron microscopy (SEM) and potentiodynamic tests. Metallographic observations indicated that MIG arc followed the rear of laser beam reheated the laser weld in the front. This resulted in increased austenite nucleation and growth in the FZ region of the flyer layer. Thermal power of MIG arc and laser arc distance were important factors, which affected grain size and alloy element content in ferrite and austenite. Potentiodynamic tests indicated that the FZ consists of fine grains with increased corrosion resistance, which was close to the parent metal exposed to chloride solution.

Effect of chemical composition on the properties of the weld metal steel welded joints 08H18AN5

The results of studies on the influence of the chemical composition of weld metal, weldstandard and new welding consumables for manual arc welding with coated electrodes, TIGwelding consumable electrode doped, automatic submerged arc welding, steel 08H18AN5 onmechanical and corrosion properties of welded joints. It is found that the mechanical properties ofwelded joints does not depend on the method and welding conditions, as conditioned by thechemical composition of the weld metal. The grain size of the HAZ in welding processes has notchanged, the 7th corresponds score as the base metal in a state of delivery. Resistance welded jointsto intergranular corrosion in the initial state after welding is caused by resistance of the weld metal,and, after provoking annealing at 6500С for an hour - resistance of the weld metal and heat affectedzone. The optimum combination of mechanical properties and resistance to intergranular corrosion08H18AN5 steel welded joints is achieved when the content of the weld metal of 17-18 %chromium, 6-7 % nickel, 2-3 % manganese, 0,12-0,15 % nitrogen, carbon 0,05 %.From the standard materials the best results are obtained by the use of wire Sv-01H19N9and Sv-07H20N9G7T with TIG welding electrodes NIAT-1 or CL-11 for manual arc welding, St-07H19N10B wire for automatic welding under flux AN-26.

Effect of Laser Beam Welding Parameters on Microstructure and Properties of Duplex Stainless Steel

The present study is concerned with laser beam welding and its effect on size and microstructure of fusion zone then, on mechanical and corrosion properties of duplex stainless steel welded joints. In this regard, influence of different laser welding parameters was clarified. Both bead-on-plate and autogenously butt welded joints were made using carbon dioxide laser with a maximum output of 9 kW in the continuous wave mode. Welded joints were subjected to visual, dye penetrant and radiography tests before sectioning it for different destructive tests. Accelerated corrosion test was carried out based on tafel plot technique. The results achieved in this investigation disclosed that welding parameters play an important role in obtaining satisfactory properties of welded joint. High laser power and/or high welding speed together with adjusting laser focused spot at specimen surface have produced welded joints with a remarkable decrease in fusion zone size and an acceptable weld profile with higher weld depth/width ratio. Besides, acceptable mechanical and corrosion properties were obtained. Using nitrogen as a shielding gas has resulted in improving mechanical and corrosion properties of welded joints in comparison with argon shielding. This is related to maintaining proper ferrite/austenite balance in both weld metal and HAZ in case of nitrogen shielding. As a conclusion, laser power, welding speed, defocusing distance and type of shielding gas combination have to be optimized for obtaining welded joints with acceptable profile as well as mechanical and corrosion properties.

Effect of the structure of weld metal on the pitting susceptibility of welded joints of ferritic-austenitic steel

The structure of welded joints of tubes from ferritic-austenitic steel 02Kh22N5AM3 is studied by methods of metallographic, x-ray diffraction, and electron microscopic analyses. Corrosion properties of welded joints are determined in pitting tests. The results of the study are used for developing a mode of welding and heat treatment that increases substantially the corrosion resistance of the weld metal.

Mechanical and corrosion properties of welded joints in a zirconium alloy when interacting with liquid cadmium and caesium

Mechanical and corrosion properties of welded joints in a zirconium alloy when interacting with liquid cadmium and caesium