Corrosion Resistance Of Welds Research Articles

Corrosion of friction stir welded magnesium alloy AM50

The microstructure of a friction stir welded magnesium alloy AM50 was examined by means of optical light microscopy. The chemical composition, particularly the iron content, and morphology of the oxide film were analyzed and discerned via auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). Corrosion behaviour of the welds and base materials were investigated by virtue of neutral salt spray tests and potentiodynamic polarization measurements in conventional cells and in a mini cell. The results demonstrate that minor increases in iron concentration as might be speculated to occur as a consequence of tool/work piece interaction during the welding process on the corrosion resistance of the weld can be ignored. The corrosion morphology was predominantly influenced by the distribution of the Mg 17Al 12 phase. Here, it was also found that the corrosion resistance of the friction stir weld varied in response to changes in the joint microstructure.

Corrosion Characteristics and Mechanical Properties of Inconel 622 Weld Overlay of Waterwall Tubes in Coal Fired Boilers

Recently in Japan, boiler waterwall tube damage such as fireside corrosion and circumferential cracking in a low NOx environment has become a serious issue, despite the fact that relatively lower sulfur content coal is typically being used than in the US. Thermal spray coating is the most popular method for tube protection in Japan, and thermal spray coating tubes are used for this purpose.However, extensive damage to thermal spray coating tubes from cracking and exfoliation has recently been experienced. It is reported that the thermal fluctuations that occur as a result of operating changes create alternating stress, leading to cracking and exfoliation of the thermal sprayed thin coating. Corrosion-resistant weld overlays, such as stainless steel type 309, alloy 625 and alloy 622, are now commonly used to protect corrosion of boiler tubes in low NOx coal fired boilers in the US. In order to develop a fundamental understanding of the high temperature corrosive behavior of alloy 622 weld overlay, gaseous corrosion testing and certain mechanical tests for consideration of long-term aging were undertaken. After one year of service in the low NOx combustion environment of a coal fired supercritical boiler, field tests on alloy 622 weld overlay panels are continuing.This report describes the behavior of alloy 622 overlay panels in a field test installed in a Japanese supercritical boiler, the laboratory results of weight loss corrosion testing, and mechanical tests related to aging.

Effect of nitrogen addition on formation of secondary austenite in duplex stainless steel weld metals and resultant properties

The gas tungsten arc (GTA) welding process is widely employed for fabricating duplex stainless steel (DSS) components. The microstructural phase balance is disturbed in DSS welds owing to the thermal cycles associated with welding and the desired phase balance is generally achieved either through control of heat input or by altering the composition. In GTA welding, the phase balance is obtained either via the use of nickel fortified fillers or by introduction of nitrogen. Control of ferrite in the welds is essential, since metastable ferrite may transform to secondary austenite during multiple pass welding. The present work describes the influence of nitrogen on the phase balance of DSS welds and also its controlling effect on the secondary austenite formation in multiple pass welds. It was observed that neither the nitrogen addition nor the secondary austenite formation influenced the hardness of the welds, but formation of secondary austenite led to a deterioration in corrosion resistance. The corrosion resistance of welds containing secondary austenite (SA) was observed to be inferior to that of SA free weld metals.

An investigation of microstructure/property relationships in dissimilar welds between martensitic and austenitic stainless steels

Abstract The metallurgical characteristics, tensile, hardness, toughness and corrosion resistance of dissimilar welds between X5CrNi18-10 grade austenitic and X20CrMo13 grade martensitic stainless steel have been evaluated. Both austenitic and duplex stainless steel electrodes were used to join this combination, using multipass manual metal arc welding process. Defect free welds were made with each welding consumable. It was found that the tensile strength of weldment, which was produced by duplex electrode (E2209-17), was slightly lower than that of austenitic electrode (E308L-16). The toughness of the both E2209-17 and E308L-16 deposits was acceptable even at low temperature regardless of heat input. Hardness was increased in both welds made with E2209-17 duplex and E308L-16 austenitic electrode along the X20CrMo13/weld metal fusion boundary due to heat annealing and then following high cooling rate. The pitting corrosion resistance of the weld metal made with E308L-16 and E2209-17 filler metal was found acceptable. Although, heat affected zone in the weldment and X20CrMo13 base metal were affected by electrolytic corrosion. This investigation has shown that both filler metals can be used to join austenitic stainless steel to the martensitic stainless steel.

A Novel Approach to Characterizing the Corrosion Resistance of Super Duplex Stainless Steel Welds

Abstract The effectiveness of electrochemical techniques in characterizing the corrosion resistance of welded super duplex stainless steels has been evaluated. Localized corrosion of the alloy-depleted zone associated with sigma-phase formation is the primary concern, with specific interest in the extent to which various methods could predict the likelihood of sustained propagation of corrosion damage due to connectivity of depleted zones. Testing was carried out on a solution-annealed super duplex stainless steel, on samples isothermally heat-treated for different periods, and on welded pipe sections produced with different heat inputs. In addition, a failed weld from service was investigated. Three electrochemical methods were utilized, viz., critical pitting temperature (CPT) measurement, electrochemical potentiodynamic reactivation (EPR), and a novel galvanostatic test. All three electrochemical methods showed sensitivity to the extent of sigma-phase content in the isothermally heat-treated samples. T...

Influence of nitrogen in the shielding gas on corrosion resistance of duplex stainless steel welds

The influence of nitrogen in shielding gas on the corrosion resistance of welds of a duplex stainless steel (grade U-50), obtained by gas tungsten arc (GTA) with filler wire, autogenous GTA (bead-on-plate), electron beam welding (EBW), and microplasma techniques, has been evaluated in chloride solutions at 30 °C. Pitting attack has been observed in GTA, electron beam welding, and microplasma welds when welding has been carried out using pure argon as the shielding gas. Gas tungsten arc welding with 5 to 10% nitrogen and 90 to 95% argon, as the shielding gas, has been found to result in an improved pitting corrosion resistance of the weldments of this steel. However, the resistance to pitting of autogenous welds (bead-on-plate) obtained in pure argon as the shielding gas has been observed to remain unaffected. Microscopic examination, electron probe microanalysis (EPMA), and x-ray diffraction studies have revealed that the presence of nitrogen in the shielding gas in the GTA welds not only modifies the microstructure and the austenite to ferrite ratio but also results in a nearly uniform distribution of the various alloying elements, for example, chromium, nickel, and molybdenum among the constitutent phases, which are responsible for improved resistance to pitting corrosion.

REMANIT 4511

Abstract Remanit 4511 was developed as a modification of Type 430 to improve its aqueous corrosion resistance. Due to its composition, that is, an addition of niobium (columbium), the alloy maintains better corrosion resistance in welds and heat-affected zone areas than does Type 430. This datasheet provides information on composition, physical properties, and elasticity. It also includes information on forming, heat treating, and joining. Filing Code: SS-659. Producer or source: Thyssen Stahl AG.

The influence of the welding process on stress corrosion

Summary The stress corrosion resistance of welds in tubes in Inconel 600 MA alloy produced by different welding processes and subjected to different service conditions is investigated.

Development of YP350 MPa Class Steels for Ice Seas Use with Improved Local Corrosion Resistance in Welds and the Properties of its Welds

Local corrosion of the welds of offshore structures in ice seas is a serious problem as the paint and cathodic protection system of the structures are damaged by the impact of ice. For this reason, the fabrication of offshore structures requires the following considerations ;(1) Local corrosion resistance of welds.(2) Excellent low temperature toughness of base metal and welds.(3) Steel products, welding materials and fabrication methods, considering weldability for wide range of welding conditions from small heat input for repair welding to large heat input for high productivity.In this paper, development of better quality steel products, welding materials, welding methods and the properties of the welds which satisfied the above requirements are reported.

Increasing the quality of welded joints in corrosion resistant steels and alloys — high alloy, corrosion resistant weld metal for aggressive media

Increasing the quality of welded joints in corrosion resistant steels and alloys — high alloy, corrosion resistant weld metal for aggressive media

Corrosion and Stress Corrosion of Arc Welds in 18% Chromium–2% Molybdenum–Titanium Stabilised Stainless Steel

A study has been made of the effect of welding on the corrosion properties of 18%Cr–2%Mo–titanium stabilisedferritic stainless steel sheetfrom 2 to 3·5 mm thickness and 9 mmplate. Welds were made using the manual metal arc, MIG and TIG processes, with matching, austenitic stainless steel and nickel-based consumables. Intercrystalline, pitting and crevice corrosion resistance of welds was evaluated, using immersion and potentiostatic techniques, with stress corrosion behaviour being assessed using transverse weld tensile samples in MgCl2 and CaCl2 solutions.Welding promoted some susceptibility to intercrystalline attack, although all welds passed the Strauss bend test criterion for sensitisation. Resistance to pitting and crevice corrosion in FeCl3 was reduced by welding. No stress corrosion was observed in the parent material, but joints made with non-matching composition consumables suffered cracking, although susceptibility was less than that associated with austenitic grades of steel. It is concluded that in most environmental situations, the loss in corrosion resistance as a result of welding will not be significant. For the highest corrosion resistance, the use of matching composition consumables is preferred.

The corrosion resistance of welds in 18–10 Mo steel to boiling nitric acid

A lecture held in Paris the 22 April 1966 during an ESAB symposium on the subject of the development of methods for electrical welding, and originally published in Esab Svetsaren, no. 1, 1968 (Box 8850, S‐402 71 Göteborg 8, Sweden.)

原子炉用ジルコニウムの溶接

The most important problem in welding of zirconium is the subject of inert gas shielding. Weld is often contaminated by atmosphere during the welding. But a proper shielding can prevent from the weld from embrittlement and deterioration of corrosion resistance of weld caused by atmospheric contamination. The best way of shielding is to use the inert gas or vacuum chamber. But an improved shielding method being applied here, even in atmospheric environment, satisfiable weld can be obtained.Generally, zirconium alloy has excellent weldability and practically ductile and corrosion resistant weld can be easily obtained without porosity nor crack.

Corrosion of stainless steel welds in acid solutions

1. Heat treatment has a great influence on the corrosion resistance of welds, those not heat treated, and those water quenched, having better properties. A short-period tempering after heat treatment considerably increases the overall rate of general corrosion. A stabilizing anneal lowers the general corrosion rate, but it is useful when followed by short-period tempering in the dangerous temperature range (i. e. within which sensitization occurs). 2. Welds suffer concentrated intergranular (knife-line) corrosion in the junction zone. The deepest corrosion is observed in welds reheated for two hours at 650°C (1200°F). 3. In acid oxidizing solutions titanium-stabilized welds corrode more rapidly than unstabilized welds. Weld metal stabilized and not stabilized with titanium, particularly after short-period tempering, suffers intergranular corrosion at the same rate.