Weld Overlays Research Articles

Optimization of Process Parameters and Mechanical Properties of 316L Stainless Steel Block via Arc Additive Manufacturing

_ A study was conducted on the influence of current, spacing, current mode, and arc length on the formation of adjacent weld overlays in the 316L stainless steel block melting process using an extremely inert gas-shielded arc additive manufacturing method. The main defect observed during the formation of adjacent weld overlays was the incomplete fusion at the bottom. When using direct current, low current and short arc length could ensure the flatness of the overlay surface, and the fusion at the bottom of the adjacent weld overlays was improved, but the problem of incomplete fusion remained unresolved. When using pulse current, low current, short arc length, and continuous welding method could solve the problem of bottom fusion of adjacent weld overlays. Due to the thermal influence during the accumulation of adjacent weld overlays, the microstructure inside the weld overlay was uneven, and the crystallographic texture in the entire weld overlay was not formed. With a pulse current of 80 A, adjacent weld overlay spacing of 4.5 mm, travel speed of 200 mm/min, dry elongation of 10 mm, and arc length of 2 mm, the tensile strengths of the block in the X, Y, and Z directions were 568.5, 570.3, and 550.7 MPa, respectively, and the fracture elongations were 46%, 48%, and 43.3%, respectively. The strength and plasticity in the Z-direction were lower than those in the X and Y directions. Keywords 316L stainless steel; arc additive manufacturing; incomplete fusion; pulse current

Influence of Substrate on the Tribological Behavior of Inconel 625 GMAW Overlays

This study investigates the microstructure and tribological behavior of Inconel 625 overlays applied via GMAW (Gas Metal Arc Welding) with and without a 316LSi stainless-steel intermediate layer on top of A36 steel. The microstructural characterization was conducted via FESEM with EDS. The tribological behavior was evaluated using a tribometer in a reciprocating configuration. The results showed that the wear rate of the Inconel 625 weld overlay with the 316LSi intermediate layer was higher than without it. However, no variations were observed in terms of hardness and the friction coefficient of the Inconel 625 weld overlays. The difference in the behavior of the two coatings was justified due to the microstructure morphology found in each case and chemical composition. When applied without the intermediate layer, Inconel 625 coating’s structure was dendritic, whereas it was cellular otherwise. An increase in the amount of Nb was observed in the layer deposited over 316LSi. This rise likely led to an increase in the number of precipitates and/or Laves phase formation. Thus, the results indicated that the difference in thermal conductivity and dilution between the stainless and carbon steels modifies the morphology of the microstructure of the Inconel 625 weld overlay, decreasing wear resistance when deposited on top of the stainless steel.

Pengaruh kompensasi, Stres Kerja dan Iklim Organisasi Terhadap Kinerja Karyawan Pada PT Cladtek BiMetal Manufactuing Batam

Human resources (HR) is one of the most important factors in a company that is used to drive other resource activities in running a company. Human resources (HR) have a fairly important position because they have a major role in company activities. PT Cladtek Bi Metal Manufacturing is a company engaged in industrial services for several jobs regarding metal materials, especially the Weld Overlay and Lining processes on carbon steel pipes aimed at industry. Compensation can motivate employees to improve work performance and compensation can also be a tool to provide or increase morale in workers. In terms of compensation at PT Cladtek Bi Metal Manufacturing, there are still some employees who feel that the compensation provided has not fully achieved the satisfaction felt by their employees. Likewise with the incident that occurred at PT Cladtek BiMetal Manufacturing, there were many employees who did not work optimally, this happened because in the assignment of very many responsibilities and also the work received was not in accordance with the field mastered, work deadlines, relationships between colleagues the work is not good and the work done is not in accordance with their abilities. The purpose of this is to determine whether compensation, work stress and organizational climate affect employee performance at PT Cladtek biMetal Manufacturing Batam. The method of data collection is through the distribution of questionnaires with a sample of 200 respondents. The type of research used by the researcher in this research is quantitative research with associative nature of research.

Influence of surface condition on the high-temperature corrosion of 12Cr1MoVG, T91, and TP347H steels in waste-to-energy boilers

High-temperature corrosion of superheater and reheater is a major obstacle for improving steam parameter of waste-fired boiler. In the present study, three commercial alloys (12Cr1MoVG, T91 and TP347H) were investigated under a simulated atmosphere. The anti-corrosion performance of Inconel 625 overlay weld coating on 12Cr1MoVG was also investigated in a real waste-to-energy (WtE) plant. The experiments were carried out by a two-zone lab-scale tube furnace where the gas temperature was 600℃ and the sample temperature was 380℃. Different sample surface conditions of the corrosion test specimens were set up includes clean surface, NaCl/KCl deposition, and ash deposition. Corrosion kinetics were plotted on the basis of specimens weight gain. The results showed that chloride salts are the main corrosive species in ash deposit. The corrosion rate of different deposits and clean surface was in the following order: KCl/NaCl > ash deposit > clean surface. The corrosion products were Fe2O3, Cr2O3, Fe3O4, NiO, (Fe, Ni)Cr2O4, FeCl2, and FeCl3. The presence of chromium was beneficial for high-temperature corrosion resistance. The anti-corrosion performance of the three alloys in descending order was TP347H > T91 > 12Cr1MoVG. This is consistent with the chromium and nickel content in the alloys. The engineering investigation showed that Inconel 625 overlay weld coating can effectively protect base material from the attack of corrosion species includes ash deposit and MSW incineration atmosphere, for long-term in real WtE plant.

Weld Overlay Restoration of Forged DI Pipe Moulds

Weld Overlay Restoration of Forged DI Pipe Moulds

Innovative prevention of stress corrosion crack propagation in nuclear power pipe welds

Abstract Failure caused by stress corrosion cracking (SCC) is inevitable during the long-term service of nuclear power pipe welds. This is mainly due to the propagation of microcracks in the deposited metal, which seriously affects the operation safety of nuclear power pressure pipes. Overlay welding is practical for pressure pipe repair welding, which can introduce compressive residual stress inside the weld seam. In this work, a diagonal T-pipe joint was fabricated using tungsten inert gas arc welding with ERRS-3 wire, and an overlay weld was also fabricated using tungsten inert gas arc welding with ERRS-3 wire under circumstances of water in the pipe and no water in the pipe. And then the contour method and finite element method were employed to measure and calculate the residual stress distribution in the diagonal T-pipe joint. Both results showed that overlay welding can introduce compressive residual stresses into the pipe joint. The compressive residual stress zone area inside the weld seam with water in the pipe is larger than that without water in the pipe, and the compressive residual stress zone area varies at different positions of the weld seam. This work is expected to promote the application of overlay weld technology in the diagonal T-shaped pipe joint repair and prevent stress corrosion crack propagation of nuclear power pipe welds.

Influence on structure and fracture mechanics evaluations of a BWR feedwater nozzle following weld overlay repair

Abstract This present paper summarizes applying weld overlay repair on the feedwater nozzle in a boiling water reactor, and evaluates the influence on the structure and fracture mechanics of the component. The requirements for utilizing a full structural weld overlay, including the weld overlay design, effects of welding residual stresses (WRSs), impacts of weld shrinkage, prediction of potential flaw growth, and influence on ASME Code Section III design evaluations, are further defined in ASME Code Case N-504–2. In order to confirm the effectiveness of the weld overlay design of the nozzle, the WRSs following overlay installation were determined using engineering simulation software. The impacts of weld shrinkage from overlay welding are also addressed. The shrinkage stresses were evaluated via a numerical model of the attached piping system to ensure the design margins of the pipe structure. Since the weld overlay technique is well known to be effective in mitigating crack initiation or cracking to leakage, a fatigue crack growth prediction under ASME Code Section XI must be conducted to address the fatigue qualification of the affected component. The ASME Code Section III construction qualification of the whole nozzle region must consider the applicable thermal transient stresses, structural discontinuities, and bimetallic effects that are caused by the weld overlay. This investigation proves that the current stress analyses of the nozzle and the pipe structure are not significantly affected by the added overlay mass, so the structural integrity of the component can be ensured, meeting the requirements of ASME Code Case N-504–2.

Research on the Microstructure and Properties of Inconel 625 Alloy by CMT/P Overlay Welding on the Inner Wall of P110 Casing

Research on the Microstructure and Properties of Inconel 625 Alloy by CMT/P Overlay Welding on the Inner Wall of P110 Casing

Effect of GMAW Process Parameters and Heat Input on Weld Overlay of Austenitic Stainless Steel 316L-Si

Effect of GMAW Process Parameters and Heat Input on Weld Overlay of Austenitic Stainless Steel 316L-Si

Microstructure and electrochemical evaluation of ER-308L weld overlays on AISI 321 stainless steel for repair applications

Weld overlaying is a promising and economical solution for repairing stainless steel structures. The present work deals with the deposition of ER-308L weld overlays on AISI 321 plate with Robotic gas metal arc welding setup. Microstructural examination depicts the presence of dendritic structures (equiaxed and columnar) and ferritic stringers. Energy-dispersive X-ray analysis confirmed the absence of precipitates and phases susceptible to corrosion in the as-deposited weld overlays. Specimens from ER-308L (weld overlay) and ER-308L&321-SS (interface) regions were subjected to electrochemical analysis using the Potentiodynamic polarization and double-loop electrochemical potentiokinetic reactivation measurements. Both overlay and interface sections exhibited comparable corrosion rate – 3.30 and 3.62 mils penetration per year, respectively with different passivation behaviour. The improved passivation behaviour of the ER-308L weld overlay authenticates the presence of δ-ferrite stringers. Double-loop electrochemical potentiokinetic reactivation tests highlighted the absence of sensitization on both weld overlay and interface specimens. This study presents the initial assessment results for repairing structural steel components subjected to corrosion damage.

High temperature corrosion resistance of FeCr(Ni, Al) alloys as bulk/overlay weld coatings in the presence of KCl at 600 °C

The long-term high temperature corrosion behavior of FeCr(Ni, Al) alloys, both in bulk form and as overlay welds, was investigated in a new experimental setup, in the presence of KCl at 600 °C. All the alloys experienced breakaway oxidation, with the bulk materials exhibiting better corrosion resistance than the overlay weld coatings with similar compositions. All results indicate diffusion-controlled kinetics, and the analysis revealed an improved corrosion behavior connected to an increased Cr content in the inward-growing scale.

Fracture Toughness Evaluation of the Heat-Affected Zone Under the Weld Overlay Cladding in Reactor Pressure Vessel Steel

Abstract The fracture toughness in the heat-affected zone (HAZ), which is located under the weld overlay cladding on the inner surface of the reactor pressure vessel (RPV), was evaluated by considering the inhomogeneous microstructures of the HAZ. In this regard, 0.4T-C(T) specimens and miniature C(T) (Mini-C(T)) specimens were manufactured to clarify the effect of the HAZ on fracture toughness. First, the fracture toughness was evaluated using 0.4T-C(T) specimens targeted on microstructural distribution due to the cladding bead location. The reference temperature (To) of HAZ at middle region of cladding bead was 12 °C higher than that at overlap cladding beads. Second, the fracture toughness was evaluated using Mini-C(T) specimens focused on the microstructural difference with distance from the boundary between the cladding and the base metal. The To value of the central position located at 3–7 mm from the boundary between the cladding and the base metal was higher than those of the other positions in HAZ. However, the To values of HAZ for both 0.4T-C(T) and Mini-C(T) specimens were significantly lower than that of the base metal at a quarter thickness by 40–60 °C. Compared with the literature data that indicated fracture toughness at the inner surface without overlay cladding and the base metal at a quarter thickness, this study concluded that the HAZ under the overlay cladding showed no detrimental effect on the conservatism of the structural integrity assessment of RPV steel.

Welding defect detection in nuclear power plant spent fuel pool panels based on alternating current field measurement: experimental and finite element analysis

The overlay panels of spent fuel pools of nuclear power plants can easily become corroded and produce micro-crack defects. Surface crack defects tend to expand vertically, horizontally and obliquely, causing damage and fracture to the overlay panels and welds of spent fuel pools. Traditional non-destructive testing (NDT) cannot complete underwater testing in real time. In order to improve the timeliness of crack detection and shorten the inspection period, research on accurate inspection technology for surface cracks in the overlay panels of spent fuel pools is carried out in this paper based on alternating current field measurement (ACFM) and the weld defect detection process for the cladding panels of spent pools is optimised. In this work, different types of artificial defect are assumed and the distortion of the magnetic field characteristic signal caused by the defects is studied. The characteristics of magnetic field signals generated in different defect regions are studied by establishing a defect electromagnetic detection model for numerical calculation. Finally, experimental and numerical results are compared and analysed. The results show that ACFM can be used to quickly and effectively inspect for cracks in the base material, weld and interface of spent fuel pool overlay panels and it has the characteristics of accuracy, high resolution, high sensitivity and low delay. The research results, which have good application value, provide technical support for electromagnetic inspection of latent cracks in field spent fuel pools and early crack warning of underwater structural defects.

Application of finite element method to effect of weld overlay residual stress on probability of piping failure

This investigation probabilistically assesses the fracture mechanics of piping welds in a nuclear power plant considering the effects of welding residual stresses. To assess the structural integrity of the welds objectively, the computer code for probabilistically analyzing the fracture mechanics of nuclear piping is utilized to estimate the leak probabilities of the welds. Aging-related degradation and the rates of growth of the cracks in the welds that are subjected to fatigue and stress corrosion cracking are considered in the Monte Carlo Simulations. To confirm the improvement in reduction of stress state that is achieved by overlay welding, a series of residual stress distributions in the welds were determined using the finite element method. The geometries, material properties and operating loads of the piping system are based on those in the stress report of the piping system. The presented results demonstrate that the leak probabilities increase with operating loads, and are significantly related to welding residual stresses. Imposing compressive stresses at the inner surface of the original pipe, a weld overlay efficiently inhibits crack propagation during subsequent operation. Furthermore, the leak probability distributions are important in evaluating the structural safety and operational stability of a piping system.

Overlay welding analysis on GTAW and SMAW processes in terms of mechanical properties and corrosion rate

The Overlay welding process is a coating technique that is carried out using the welding process. In this study, a coating was conducted on carbon SA 516 gr. 70 with stainless steel electrodes. Welding was carried out with the GTAW and SMAW processes. The electrode used in the first coating for GTAW was ER309L while for SMAW was E309L. The next coating used in the GTAW electrode was ER316L and the SMAW electrode was E316L. In both welding processes, testing was carried out on mechanical properties and corrosion rates. Testing was carried out to determine mechanical properties, namely bending testing. This was done based on ASME IX. Bending test results in both processes are declared accepted because there are no defects. In testing the corrosion rate using the three-electrode cell method based on the ASTM G102 Overlay welding process with GTAW has a slower corrosion rate of 0.00890 MMPY compared to the overlay welding process with SMAW.

Influence of girth welding material on thermal and residual stress fields in welded lined pipes

An experimental and numerical investigation on the thermal and mechanical response of a lined pipe (compound pipe) under welding is presented. The welding process consists of a single-pass overlay welding (inner lap-weld) and a two-pass girth welding (outer butt-weld). The influence of the filler material of the girth welding has been examined thermally and mechanically as it is a key factor that can affect the quality of lined pipe welding. To this end, a three-dimensional non-linear finite element model based on the ABAQUS code has been developed and successfully validated against small-scale experimental results. This study was conducted on two specimens of lined pipe joined together by a girth welding deposited either by mild steel or by austenitic stainless steel. Furthermore, in this study, a pre-heat treatment required to produce lined pipe specimens has been taken into account. Strains and residual stresses have been measured by means of high temperature strain gauges, residual stress gauges and the X-ray diffraction technique along the inner and outer surfaces of the welded lined pipe whereas the thermal history has been recorded by thermocouples. The findings point out that replacing the girth welding mild steel by austenitic stainless steel has a significant effect on the residual stress results but no influence on the thermal history results.

Metallurgical aspects and electrical resistivity of hardfaced pure copper layers over AISI 347 with cold metal transfer process

Pure Copper having excellent electrical conductivity was deposited over AISI 347 substrate using Cold Metal Transfer (CMT) process to obtain quality weld overlays without defects. To improve the electrical conductivity post heat-treatment was performed. The microstructural examination revealed the presence of Cu-FCC and Fe-FCC along with retained delta ferrite at the bi-metallic interface. Also, the existence of bi-phasic spherulites rich in Fe and Cr were noticed in the weld overlay side while Cu spherulites were observed in the AISI 347 substrate adjacent to the bi-metallic interface. Energy Dispersive X-Ray Spectroscopy (EDS) elemental mapping and line scan data confirmed the presence of spherulites due to solid-state diffusion near the interface. The spherulite size was reduced in the heat-treated weld overlays and a small fraction of Cu spherulites were observed in the interface. The microhardness of the as-deposited and heat-treated weld overlays revealed the transition of elements at the bi-metallic interface. Post heat-treatment of Cu weld overlays improved the electrical conductivity significantly in comparison to the as-deposited ones. These electrical measurements suggest that pure Cu weld overlays with sufficient conductivity shall be attained with the CMT process for electrical and power generation applications.

Impact of Overlay Welding Repair on Bulges during Normal and Short Cycles in Coke Drums

Impact of Overlay Welding Repair on Bulges during Normal and Short Cycles in Coke Drums

Effect of Preheat Temperature and Welding Sequence on the Temperature Distribution and Residual Stress in the Weld Overlay Repair of Hydroturbine Runner.

The hydroturbine runner is the core of the whole hydroelectric generating unit, which is employed to transform water energy into mechanical energy. In the process of service, the runner frequently suffers from abrasion due to erosion and cavitation. Defects are usually repaired by welding. To acquire suitable weld cladding repair process parameters, a combination of experimental and numerical simulation was applied to investigate the temperature and weld residual stress distribution in the repair zone under the different welding repair approaches. The results illustrate that the temperature and welding residual stress distribution of the blade and the shroud are out of symmetry, the temperature conduction rate is faster on the blade side, and the high-stress zone is predominantly concentrated in the weld and its adjacent area. When the preheating temperature is up to 150 °C, the peak value of welding residual stress reaches a minimum of 796.29 MPa. The welding sequence can adjust the distribution trend of welding residual stresses. The welding sequence of three-stage welding can effectively reduce the welding residual stresses near the shroud at the water outlet side of the blade. The results of the study will provide theoretical guidance for the welding repair of hydraulic turbine runners.

Numerical simulation of residual stress in post internal-welding process of bimetal composite pipe and optimization of welding sequence

With the increasing demand for energy, energy extraction is developing towards a more complex corrosive environment containing a large amount of CO2, H2S and Cl−. Bimetal composite pipes because of both good corrosion resistance and strength are getting more and more research and application. In this paper, L415/316L bimetal mechanical lined pipes were welded by two processes (single-side welding process and post internal-welding process) the residual stress of which was studied by combining numerical simulation and experiment. Then the welding sequences of the post internal-welding process were compared and analyzed. The results show that there is already a certain amount of residual stress in the pipe after overlay welding. The residual stress of single-side welding process and post internal-welding process is too large and distributes in the danger zone, which is easy to lead to failure. By adjusting sequence of the post internal-welding, it can effectively change the level of the residual stress and reduce the stress of the overlay layer, the internal-welding layer and the backing welding layer, which is beneficial to improve the safety of the bimetal mechanical lined pipe.