Weld Reinforcement Height Research Articles

Decoupling the role of microstructure and geometric discontinuity introduced by weld reinforcement height on corrosion behavior of SA106B/316L SS welded joint in the flowing 0.5 M NaCl solution

The flow-influenced corrosion (FIC) behavior of SA106B/316L stainless steel (SS) welded joints with SS located upstream and downstream is investigated experimentally and numerically. The damage components of microstructure heterogeneity and geometric discontinuity are quantified. The FIC of the welded joint is affected by the combination of galvanic corrosion, mass transfer, and charge transfer. The electrochemical measurements indicate that the corrosion is aggravated by a flow disturbance component of 18.70∼26.96%. The corrosion of SA106B carbon steel is more severe than 52M and 316L SS due to galvanic effect, which is further promoted by flow disturbance. The FIC mechanism is also discussed.

CFD-DPM modelling of solid particle erosion on weld reinforcement height in liquid-solid high shear flows

Liquid-solid two-phase flow erosion can lead to great economic losses and safety concerns in the oil & gas storage and transportation industry. The solid particle erosion on weld reinforcement height (WRH) in liquid-solid high shear flows were systematically investigated by coupling the computational fluid dynamics (CFD) and the discrete phase model (DPM) method. The effects of liquid velocity, WRH height, particle flow rate, and particle size on the particle erosion in the WRH region were analyzed. Increasing erosion rate was observed with increasing liquid velocity. The erosion rate first increased and then decreased with increasing WRH height. The increasing erosion rate was observed with both increasing particle flow rates and particle sizes. The existence of defects on the WRH surface significantly increased the maximum erosion rates. This work can provide scientific guidelines for the corrosion protection and safe operation of long-distance oil & gas pipelines.

Effect of Local Fluid Disturbance Induced by Weld Reinforcement Height on the Corrosion of a Low Alloy Steel Weld

Weld corrosion exists widely in the petrochemical industry and attracts great attention. Most research proves that weld corrosion originates from the material factors introduced during the welding process. However, it is noted that local fluid turbulence due to the weld reinforcement height (WRH) plays an important role in the non-uniform corrosion of welds in flowing media. Accordingly, the individual effect of the local flow on the weld corrosion of low alloy steel was analyzed by experiments and simulation in this study. Electrochemical measurements and morphology observation were conducted, combined with flow field analyses. The results showed that local fluid turbulence due to WRH affected the non-uniform corrosion of low alloy steel welds. The upstream surface and the backflow surface had the highest and lowest corrosion rates, respectively. Interestingly, the high flow velocity surface region did not have a high-corrosion rate. This is due to the combined effects of mass transfer, charge transfer, and wall shear stress. The pitting corrosion was also discussed in view of the aspects above.

Application of Taguchi method and ANOVA analysis for optimization of process parameters and exothermic addition (CuO-Al) introduction in the core filler during self-shielded flux-cored arc welding

The main factors affecting the mechanical properties of the deposited metal in arc hardfacing are primarily the chemical composition and the cooling rate. The latter depends on the filler materials composition, hardfacing condition (mode), and hardfacing technology, determining the geometric parameters and parameters of the welded bead shape, the amount of deposited metal dilution with the base metal, and the amount of the introduced heat. The goal of this work is to analyze the effect of exothermic addition introduction to the core filler and the effect of welding condition on weld bead morphology, thermal indicators, and mechanical properties of the deposited metal. The deposited metal of the Fe-C-Cr-Cu-Ti-V-Al alloying system was used. The Taguchi technique was adopted as the experimental plan design, as follows: the orthogonal array L9 (3 ^ 4) and signal-to-noise ratio (S/N). The analysis of variance (ANOVA) was also applied for determination of the variables contribution to the dependent parameters. Application of the Taguchi method is simpler, more efficient, and quicker. It requires fewer experiments to determine the optimal values of the studied variables. Microstructural studies using an optical microscope were additionally performed for individual samples of the weld metal with the best mechanical properties, for each of the experimental flux-cored wires. We determined that introduction of CuO-Al exothermic addition of to the core filler had a significant effect on such indicators of the weld bead morphology as the weld reinforcement height and the weld reinforcement form factor (WRFF). Introduction of exothermic addition (CuO-Al) to the core filler had a significant effect on the welding current (I), heat input rate (HIR), and microhardness. The arc voltage (Р(Ua) = 45.8 %) had the greatest influence on the microhardness value, while the percentage of exothermic addition in the core filler (P (EM) = 26.9%) and the wire feed rate (P (WFS) = 21.5%) had a smaller effect. It was shown that it is important to take into account complex parameters, such as dilution variation and weld reinforcement form factor (WRFF) for the geometric characteristics of the weld bead and heat input rate (HIR) for heat indicators in order to optimize hardfacing conditions and composition of the core filler (introduction of exothermic addition). According to the results of the article, the value is the most correlated with the average values of microhardness.

Effect of Welding Current and Electrodes on Reinforcement Height in Shielded Metal Arc Welding Process

Joining of materials is the need of modern industries and stuctures. Shielded metal arc welding process is one of the most popular and commonly used method of joining materials. The weld reinforcement height should be optimum for mechanical properties of the weld. If the reinforcement height is less or negative, it is not recommended considering strength of weld as surface area will be reduced and if the reinforcement height is more, it will produce stress concentration which is not recommended. In the present work the investigation of the effect of three different types of electrodes at three different welding currents in shielded metal arc welding process utilizing Low Carbon Steel plate of API 5L Grade X 52, was done for reinforcement height. The three different electrodes as E 6013, E 7016 and E 7018 and the varying currents as 90 A, 100 A and 110 A. Total 18 pieces were used to obtain 9 welds which were used to analyze the effect of current and the electrode on reinforcement height. The dimensions of the work pieces were taken as 75 mm x 50 mm x 5 mm. The values of reinforcement height in each weld were written in a table and respective diagrams were drawn to make clear the effect of welding current on reinforcement height for the three different electrodes.

Microstructural change during laser welding of Inconel 718

In this study, Inconel 718 superalloy has been subjected to laser welding using a 2 kW continuous wave (CW) Yb-Fibre laser at a constant power of 1800 W with a varied scan speed of 1400 mm/min, 1200 mm/min, and 1000 mm/min, respectively. The effect of process parameters on microstructure, and microhardnes and nano-mechanical property has been studied. There is formation of reinforcement on the face of the weld zone and sometimes in the root. The weld reinforcement height has been found to vary from 51.3 μm to 72.9 μm and increases with increase in scan speed of laser beam. The microstructure of the weld zone is fine columnar in the solid liquid interface followed by dendritic region and with equiaxed morphology in the middle. In the inter-columnar, interdendritic or grain boundary regions there are presence of gamma and gamma prime precipitates. The orientation of grains in terms of micro-texture has been carefully analysed by EBSD analysis. The texture of the weld zone is marginally different from that of the base metal. There is a marginal decrease in microhardness (from 280 VHN for as-received to 246 VHN) in laser welded Inconel 718. A detailed nano-mechanical property of the weld zone has been studied by nano-hardness measurement.

A Study on Microstructure, Residual Stresses and Stress Corrosion Cracking of Repair Welding on 304 Stainless Steel: Part II-Effects of Reinforcement Height.

The repair reinforcement height is an important parameter of repair welding, which may have a great influence on structural integrity. In this paper, the effects of repair welding reinforcement height on the microstructure, microhardness, residual stresses and stress corrosion cracking (SCC) behavior of a 304 stainless steel-repaired joint were investigated by experimentation and simulation. With an increase of the repair weld reinforcement height, the δ ferrite content in weld and fusion zone is obviously reduced, and the ferrite shape is gradually changed from the skeleton to the worm shape. With the increase of repair welding reinforcement height, the microhardness and residual stresses decrease gradually. The tensile strength and elongation for higher repair weld reinforcement height are larger than those with lower repair weld reinforcement height. The higher the repair weld reinforcement height, the harder it is for SCC to occur. The repair welding in 304 stainless steel is recommended to be repaired no more than two times.

Fracture behavior of clad pipeline containing a canoe shape surface crack subjected to large bending moment

This paper concerns the fracture assessment of a clad pipeline subjected to large bending moment, and identifies different parameters influencing the fracture behaviors. The evolution of Crack Tip Opening Displacement (CTOD) of a pipeline containing a canoe shape crack on the external surface of the girth weld is studied under pure bending and combined pure bending and internal pressure through 3D elastic-plastic Finite Element (FE) simulations. Various parameters affecting the evolution of CTOD like crack depth, crack length to perimeter diameter ratio, internal pressure and the weld geometrical configurations have been investigated. It is observed that only the average width of the weld has a significant influence on the fracture response under pure bending, while the weld reinforcement height and fusion line slope have a moderate influence on the fracture behavior under biaxial loading. The crack at the interface between the weld and back steel has a similar fracture response to that of a crack located in the weld with equivalent effective crack depth. Finally, a strain based Failure Assessment Diagram (FAD) is proposed and compared with the fracture assessments produced by BS7910:2013, and 3D elastic-plastic FE simulations suggest that the British Standard is more conservative especially for deep cracks.

Evaluation of Welding Residual Stress Based on Temper Bead Welding Technique

To reduce welding residual stress (WRS) of a class 3 pressure vessel during the reconstruction, temper bead welding technique (TBWT) was applied to the container. To compare WRS causing by common welding and TBWT, WRS of the two different kinds of welded specimens of 16Mn steel were measured and evaluated by X-ray method. To study the effect of butt weld reinforcement height on WRS, welds with and without weld reinforcement were measured. The results show that longitudinal stress was reduced obviously and the lateral stress is the maximum principal stress for TBWT; WRS of TBWT T-shape specimens were obviously decreased which proves TBWT is better than common welding procedure; WRS was decreased by more than 25% after removing the weld reinforcement and further proves that it is one of effective ways to reduce WRS in engineering application.

Prediction of weld quality in pulsed current GMAW process using artificial neural network

Weld joint dimensions and weld metal mechanical properties are important quality characteristics of any welded joint. The success of building these characteristics in any welding situation depends on proper selection-cum-optimisation of welding process parameters. Such optimisation is critical in the pulsed current gas metal arc welding process (GMAW-P), as the heat input here is closely dictated by a host of additional pulse parameters in comparison to the conventional gas metal arc welding process. Neural network based models are excellent alternatives in such situations where a large number of input conditions govern certain outputs in a manner that is often difficult to adjudge a priori. Six individual prediction models developed using neural network methodology are presented here to estimate ultimate tensile strength, elongation, impact toughness, weld bead width, weld reinforcement height and penetration of the final weld joint as a function of four pulse parameters, e.g. peak current, base current, pulse on time and pulse frequency. The experimental data employed here are for GMAW-P welding of extruded sections of high strength Al–Zn–Mg alloy (7005). In each case, a committee of different possible network architectures is used, including the final optimum network, to assess the uncertainty in estimation. The neural network models developed here could estimate all the outputs except penetration fairly accurately.