Austenitic Steel Weld Research Articles

Weldability of austenitic stainless steel by metal arc welding with different shielding gas

During fusion welding the molten metal is shielded from contact with the atmospheric gas by means of a gaseous flux. The shielding gas prevents weld embrittlement, affects welding quality, because of its influence on filler metal transfer, and has a direct impact on welding costs as well. Argon is the most common shielding gas, often used with some adds of other gases that can be inert, as helium, or active, as CO2, O2 or H2. In this work the effects of mixtures with different composition have been considered for the arc welding of austenitic steels. Metallographic samples of welded sections have been undergone to visual and optical microscopy observations, microhardness, indentations and tensile tests.

Influence of Arc Welding Power Supply on Structural Phase Composition of X12CrNiTi 18-9 (DIN) Weld

The paper presents the results of studies improve efficiency of manual arc welding of austenitic steels. It is in arc welding of austenite steels the use of inverter power supply furthers obtaining more fine-grained structure of added metal and thermal impact zone, shortens thermal impact zone; that improves corrosion resistance of joint weld.

Comparative study of evolution of residual stress state by local mechanical tensioning and laser processing of ferritic and austenitic structural steel welds.

Complex thermal stresses generated in welded structures are undesirable but inevitable in fusion welding. The presence of residual stresses can be detrimental to the integrity of a welded joint. In this research, redistribution of residual stress magnitude and profile was studied and compared in two multi-pass welded structural alloys (API X100 and 304L stainless steel) after cold rolling and laser processing. The residual stress field was studied by neutron diffraction using the SALSA strain scanner at their reactor neutron source at ILL, Grenoble. In addition to a complex distribution of residual stress state, multi-pass welds also forms dendritic grain structure, which are repeatedly heated, resulting in segregation of alloying elements. Dendritic grain structure is weaker and segregation of alloying elements may result in formation of corrosion microcells as well as reduction in overall corrosion prevention due to depletion of alloying elements in certain areas. The modification of as-welded residual stress state was done by cold rolling which was followed by laser processing to create a recrystallized microstructure to minimise segregation. The main objective of this study is to understand the suitability of this novel manufacturing technique to create a stress free weldment with recrystallised grain structure. Hardness evolution in the welded structures was scanned following welding, post weld cold rolling and cold rolling followed by laser processing. Hardness distribution in both the structural alloys showed a significant evidence of plastic deformation near the cap pass of the weld metal. Residual stress redistribution was observed up to 4 mm from the capping pass for ferritic steel, while in austenitic steel weld, post weld cold rolling was effective in modifying the residual stress redistribution throughout the entire thickness. Laser processing in both cases reinstated the as-welded residual stress distribution and resulted in softening of the strained area.

Effect of silicon on the solidification cracking behavior and metastable carbide formation in austenitic high Mn steel welds

Addition of 1.5 wt.% Si into Fe–18Mn–0.6C steel noticeably increased the tendency of solidification cracking. Extensive segregation of Si at the dendritic and grain boundaries suppressed the formation of (Fe,Mn)3C eutectic carbide during solidification. On the other hand, Si segregation led to the formation of a metastable carbides consisting of a mixture of (Fe,Mn)5SiC and (Fe,Mn)23C6.

Hydrogen distribution and hydrogen cracking susceptibility of a martensitic–austenitic steel welding wire

Hydrogen distribution and cracking susceptibility of a martensitic–austenitic steel weld in ambient atmosphere and in aggressive chemical environment was evaluated by measuring hydrogen desorption at a constant heating rate. In ambient atmosphere, most of the hydrogen is trapped in austenite phase, thus the weld is not susceptible to hydrogen cracking. In chemical environment, diffusible hydrogen content of the weld is much higher than the critical hydrogen level to cause cracking, thus weld metal is highly susceptible to hydrogen cracking.

Electrodes for welding of dissimilar chromium martensitic and chromium-nickel austenitic steels

The Paton Welding Journal, 2014, №06. International Scientific-Technical and Production Journal «The Paton Welding Journal» «The Paton Welding Journal» has been published monthly since 2000 in English, ISSN 0957-798X. «The Paton Welding Journal» is a cover-to-cover English translation of the «Avtomaticheskaya Svarka» (Automatic Welding) journal. The «Avtomaticheskaya Svarka» journal has been published monthly since 1948 in Russian, ISSN 005-111X.

Mechanical Properties of Interface of Heterogeneous Diffusion Welds of Titanium and Austenitic Steel

Titanium is material which is used in many areas of human activity. Therefore it is necessary to join it with other material. It is very difficult to welding Ti with other metals by conventional fusion welding methods. There exist special joining technologies of heterogeneous materials which is possible to use. This is usually a joining of materials in the solid state, as diffusion welding, friction welding or explosion welding. This contribution deals with diffusion welding of titanium alloy Ti6Al4V and stainless austenitic steel 1.4301. There are described mechanical properties (as is reduced modulus Er and indentation hardness HIT) and changes of chemical composition of join due to diffusion of elements.

A technology for arc welding cold-rolled pipes produced from new austenitic steels

To produce components of a power plant, working at temperatures of up to 750°C, investigations were carried out to develop a technology and carry out computer modelling of the method of combined argon-shielded arc and manual arc welding of experimental austenitic steels. The tests of the mechanical properties and metallographic analysis confirm the satisfactory characteristics of the strength and ductility properties of the welded joint and the absence of any susceptibility to hot cracking in welding new austenitic steels.

Monte carlo inversion of ultrasonic array data to map anisotropic weld properties

The quality of an ultrasonic array image depends on accurate information about its acoustic properties. Inaccurate acoustic properties can cause image degradation such as blurring, mislocation of reflectors, and the introduction of artifacts. In this paper, for the specific case of an inhomogeneous and anisotropic austenitic steel weld, Monte Carlo Markov Chain (MCMC) inversion is used to estimate unknown acoustic properties from array data. The approach uses active beacons that transmit ultrasound through the anisotropic weld; the ultrasound is then captured by a receiving array. A forward model of the ultrasonic array data is then optimized with respect to the experimental data using an MCMC inversion. The result of this process is the extraction of a material property map that describes the anisotropy distribution within the weld region. These extracted material properties are then used within an imaging algorithm-the total focusing method in this paper-to produce autofocused images. This MCMC inversion approach is first applied to simulated data to test the convergence, robustness, and accuracy of the method and its implementation. The extracted weld map is used to show improved imaging of defects within the weld, relative to an image formed assuming a constant velocity. Finally, the MCMC inversion approach is used on experimental data from a 110-mm-thick steel plate containing an austenitic weld. Here the extracted weld map is used to show that defect location errors of greater than 5 mm are reduced to around 2 mm when the extracted weld map is used.

The application of magnetic structural phase analysis for the diagnostics of the State of a 08X18H10T Steel-Ct3 Steel composite material and its components that were subjected to plastic deformation

The use of composite, in particular, multilayer materials, is one way to decrease the specific quantity of metal in an item and to increase its service characteristics. To develop methods for the diagnostic of the state of such composite materials and their components, the effect of cold rolling on the structure, magnetic, and mechanical properties of a two-ply composite material and its separate components was studied; the material was prepared by explosion welding of austenitic corrosion-resistant and low-carbon steels. It was shown that magnetic characteristics can be used for estimating the degree of deformation by rolling, phase composition, and mechanical properties of both two-ply 08X18H10T Steel-Ct3 Steel composite material as a whole and its separate components.

Electrochemical method for pickling and passivation of austenitic steel welds

The aim of this work is to develop an innovative process for pickling and passivating tungsten inert gas welds on austenitic stainless steel in order to obtain complete removal of non-protective oxides and to passivate the metal surface. In particular, the treatment intends to increase both corrosion resistance and surface appearance of the steel without making use of traditional pickling solutions (which usually contain high concentrations of strong acids). The treatment, based on an electrochemical approach, uses specific electrolytes, and to evaluate their effect in terms of corrosion resistance and surface finish, different solutions were prepared and tested using low concentrations of weak organic acids, e.g. citric, oxalic, sulphamic, gluconic and lactic acids. This aspect is very important to reduce the hazardousness of the solution compared to the traditional pickling acids.

Microstructure and Corrosion Resistant Property Research of Super 304H and TP347H Heat-Resistant Steel Welding Joint

Microstructure of Super 304H and TP347H austenitic heat resistance steel welding joint by handwork argon tungsten-arc welding and electro-chemical corrosion property of weld metal and two base materials were investigated by SEM and M273 constant potential rectifier. The results shows that microstructure of the weld metalwere austenitic matrix + δ ferrite; In 5% HCl Solution, corrosion resistant capabilities were super 304H base material＞ weld metal＞TP347H base material; in 9.8% H2SO4 Solution, corrosion resistant capabilities were Super 304H base material＞TP347H base material＞ weld metal; Super 304H and TP347H austenitic heat resistance steel welding joint has better corrosion resistant property in HCl solution than in H2SO4 solution; Inter-crystalline corrosion results were consistence to results electro-chemical corrosion experiment in 9.8% H2SO4 solution.

Design of weld fillers for mitigation of residual stresses in ferritic and austenitic steel welds

Residual stresses that arise as a result of welding can cause distortion, and also have significant implications for structural integrity. Martensitic filler metals with low transformation temperatures can efficiently reduce the residual stresses generated during welding, because the strains associated with the transformation compensate for thermal contraction strains during cooling. However, it is vital that a low weld transformation temperature is not obtained at the expense of other important material properties. This article outlines the alloy design process used to develop appropriate low transformation temperature filler materials for the mitigation of residual stresses in both low alloy ferritic and austenitic stainless steel welds. Residual stresses in single pass, 6 mm bead in groove welds, on 12 mm thick plates, have been measured and compared against those obtained with commercially available conventional austenitic and ferritic filler materials. The filler metals developed here exceeded requirements in terms of weld mechanical properties, while significantly reducing the maximum residual stress in the weld and heat affected zone.

Correction of ultrasonic array images to improve reflector sizing and location in inhomogeneous materials using a ray-tracing model

The use of ultrasonic arrays has increased dramatically within recent years due to their ability to perform multiple types of inspection and to produce images of the structure through post-processing of received signals. Phased arrays offer many advantages over conventional transducers in the inspection of materials that are inhomogeneous with spatially varying anisotropic properties. In this paper, the arrays are focused on austenitic steel welds as a representative inhomogeneous material. The method of ray-tracing through a previously developed model of an inhomogeneous weld is shown, with particular emphasis on the difficulties presented by material inhomogeneity. The delay laws for the structure are computed and are used to perform synthetic focusing at the post-processing stage of signal data acquired by the array. It is demonstrated for a simulated austenitic weld that by taking material inhomogeneity and anisotropy into account, superior reflector location (and hence, superior sizing) results when compared to cases where these are ignored. The image is thus said to have been corrected. Typical images are produced from both analytical data in the frequency domain and data from finite element simulations in the time domain in a variety of wave modes, including cases with mode conversion and reflections.

The application of Fermat's principle for imaging anisotropic and inhomogeneous media with application to austenitic steel weld inspection

Ultrasonic inspection in anisotropic and inhomogeneous media has long presented a challenge because of the complex steering of ultrasonic paths. An approach is presented in which the true geometry of a previously used austenitic steel weld model is distorted so that, from one viewing location, all ultrasound travels in straight lines with a constant isotropic velocity. The mapping from the real space to this distorted space is accomplished using Fermat’s theorem of least travel time applied through ray tracing. Applications specific to inspection design and data interpretation for manual ultrasonic inspection of welds in austenitic steel plates are given. Validation of some intermediate results is provided using finite element analysis.

Compositional boundary between primary austenitic and ferritic Mn–Cr and Ni–Cr steel weld metals

The compositional boundary between primary austenitic and primary ferritic steel weld metals is revised. An extension that agrees with previously defined ones and expands the concept to leaner nickel compositions and richer manganese contents is proposed. In an effort to make this Cr eq/Ni eq boundary as exact as possible for different alloying ranges, a change of the effect of manganese in the stabilization of austenite at different alloying levels in the form of a new coefficient is devised. The manganese (coefficient) effect is then compared with those from other studies to present a general panorama of its complex behavior.

Use of A-TIG method for welding of titanium, nickel, their alloys and austenitic steels

Use of A-TIG method for welding of titanium, nickel, their alloys and austenitic steels

Corrosion resistance of the high‐strength filler metal NiCr20Fe14Mo11WN (alloy 50 PLUS)

AbstractThe Nb‐free NiCr20Fe14Mo11WN alloy has been developed as a new filler metal which combines high strength and excellent corrosion resistance in wet environments at ambient temperatures.The alloy is characterized by exceptional resistance to pitting and crevice corrosion, no sensitiveness to chloride induced stress corrosion cracking and shows high mechanical properties, e.g. 0.2 %‐yield strength.Because the alloy is practically free of stable nitride formers like niobium, titanium etc., no nitride formation during welding of super austenitic, duplex and super duplex steels is possible, which proves the alloy to be superior to alloy 625.

Factors affecting reheat cracking in the HAZ of austenitic steel weldments

Reheat cracking in the heat affected zones of austenitic stainless steels can occur during high temperature service and is thought to arise from the relaxation of welding residual stresses, resulting in creep damage. Key features of reheat cracking are the magnitude of the residual stresses, degree of triaxiality, extent of stress relaxation behaviour and the influence of triaxial stress on creep ductility. A thermo-mechanical pre-conditioning technique has been developed for testing specimens to represent the welding cycles experienced between 200 and 1100 °C by the ‘strain affected zone’ of a weldment in a steam header during manufacture. Subsequent creep tests have been carried out at 550 °C on pre-conditioned plain and notched specimens to identify the behaviour as regards creep rate and ductility in both the uniaxial and triaxial stress states. The results have been compared with data in the literature and with models of the influence of multiaxial stress on creep ductility. It has been found that certain types of pre-conditioning give a marked reduction in creep ductility as strain rate is reduced, which helps to explain the reheat cracking process.

102 オーステナイト鋼溶接部の超音波伝搬解析

102 オーステナイト鋼溶接部の超音波伝搬解析