Weld HAZ Research Articles

Comparative corrosion behavior of three titanium alloy base materials and their welds in a simulated chimney environment

This study investigates the corrosion behavior of titanium alloys (TA2, TC4, TB6) in a 3 % sulfuric acid flue gas environment using electrochemical tests and microscopic analyses (SEM/EDS, XRD, metallographic microscopy). Results show that TA2 base metal has lower corrosion resistance compared to its weld metal, while TC4 and TB6 exhibit opposite trends. Specifically, TC4 and TB6 base metals have lower corrosion current densities (0.9 and 0.5 μA/cm2) and higher corrosion potentials then their weld metals (1.93 and 2 μA/cm2). In contrast, TA2 base metal showed higher corrosion current density (2 μA/cm2) than its weld metal (0.35 μA/cm2) and HAZ metal (0.16 μA/cm2).Microscopic analyses reveal β phase transitions in TC4 and TB6 weld areas, leading to larger grain sizes and reduced corrosion resistance. Conversely, TA2 retains finer grains post-welding, enhancing its corrosion resistance. These insights clarify weld corrosion effects and provide valuable guidance for industrial applications of titanium alloys, particularly in designing and maintaining titanium alloy chimneys.

A novel approach to suppression of reverted austenite in aerospace grade thick maraging steel weldments using the turbo-TIG welding process

This research examines aerospace grade-maraging steel weldments produced by the novel Turbo-TIG welding technique. The vital challenge in welding maraging steel is the development of reverted austenite in the weld region and HAZ. This reverted austenite degrades the mechanical characteristics of weldments. MDN 250 maraging steel with a 12 mm thick plate was welded at a high speed of 300 mm/min with consistent quality using the Turbo-TIG welding technique. The objective of the present work is to suppress the reverted austenite in the 12 mm thick plate of MDN 250 using the Turbo-TIG welding technique. Three different postweld heat treatments were applied, namely, (i) aging heat treatment (AT), (ii) solutionizing + aging (ST), and (iii) homogenization + solutionizing + aging (HT). The microstructure and X-ray diffraction analysis of the weld zone under AT and ST conditions demonstrate the existence of reverted austenite in the grain boundary regions. The SEM/EDS analysis of the weld zone of welded, AT, and ST conditions indicated Ni, Mo, and Ti microsegregation from the center matrix to the grain boundary regions. In contrast, neither microsegregation nor austenite reversion occurred in the HT condition. The tensile test demonstrates a maximum strength of 1797 MPa (UTS) under HT conditions. Likewise, the microhardness of the HT conditions exhibits a higher hardness of 552 HV in the fusion zone. In light of the metallurgical and mechanical characteristics of the weld, the HT heat treatments provide better weld performance in the case of Turbo-TIG welding of maraging steel grade MDN 250.

Underwater Friction Welding of Low Carbon Steel

In this study, an attempt was made to obtain a welded joint from the underwater friction welding (UFW) process. The workpiece material used in this experiment was AISI 1018 low carbon steel. The experiment was carried out on a friction welding machine which was designed and manufactured for this purpose. The UFW process was carried out by varying the spindle rotation used to rotate one of the workpieces. The friction force was kept constant. The quality of the welded joints resulting from UFW was determined by measuring the misalignment that occurs in the weld joint, the macro and micro structures formed, as well as the mechanical properties of the welded joint. For comparison, friction welding in air (FW) was also carried out. The results obtained indicate that low spindle rotation results in high misalignment of the welded joint between the two workpieces. During the UFW process, rapid cooling occurs so that the microstructure of the weld metal, TMAZ and HAZ is dominated by a fine pearlite phase so that the hardness and strength of the weld joint are higher than those produced by FW process in air.

Crack driving forces under creep conditions in presence of material inhomogeneity

ABSTRACT Under time-dependent creep deformation in metallic materials in the presence of a crack, the driving force is influenced at a distance in the presence of a zone (such as an interlayer, interface, hole, etc.) which deforms differently in reference configuration. This influence may increase or decrease the crack driving force based on the type of inhomogeneity (elastic, plastic, creep). The nature and extent of influence of material inhomogeneity are studied in this work with a configurational force-based rate of crack driving force definition for a crack in the presence of dissimilar metal weld zone, HAZ and second base metal.

Influence of nitrogen content on the pit formation and pit propagation in the welded joints of X5CrNi18‐10 stainless steel

AbstractThe influence of welding current and nitrogen content in argon shielding gas on the resistance of the welded joint (weld metal and heat‐affected zone [HAZ]) of the stainless steel X5CrNi18‐10 to the formation and growth of pits was investigated. Also, the susceptibility of the welded joint to intergranular corrosion was examined. Pitting corrosion resistance indicators were determined based on anodic potentiodynamic polarization measurements in NaCl + Na2SO4 solution, while susceptibility to intergranular corrosion was determined by the potentiokinetic method with a double loop (DL EPR). SEM/EDS was used to analyze the microstructure. It has been shown that higher nitrogen content in shielding gas leads to an increase in the resistance of welded joints (weld metal and HAZ) to the pit formation. However, an improvement in the resistance to the pit formation leads to a decline in the resistance of the welded joint to pit growth. An explanation of this phenomenon is proposed. Also, it was shown that the increase of the welding current increases the susceptibility of the welded joint to intergranular corrosion, while the higher nitrogen content has no effect.

An Improved Method for Deriving the Heat Source Model for FCAW of 9% Nickel Steel for Cryogenic Tanks.

The International Maritime Organization (IMO) is tightening regulations on air pollutants. Consequently, more LNG-powered ships are being used to adhere to the sulfur oxide regulations. Among the tank materials for storing LNG, 9% nickel steel is widely used for cryogenic tanks and containers due to its high cryogenic impact toughness and high yield strength. Hence, numerous studies have sought to predict 9% nickel steel welding distortion. Previously, a methodology to derive the optimal parameters constituting the Goldak welding heat source for arc welding was developed. This was achieved by integrating heat transfer finite element analysis and optimization algorithms. However, this process is time-consuming, and the resulting shape of the weld differs by ~15% from its actual size. Therefore, this study proposes a simplified model to reduce the analysis time required for the arc welding process. Moreover, a new objective function and temperature constraints are presented to derive a more sophisticated heat source model for arc welding. As a result, the analysis time was reduced by ~70% compared to that previously reported, and the error rates of the weld geometry and HAZ size were within 10% and 15% of the actual weld, respectively. The findings of this study provide a strategy to rapidly predict welding distortion in the field, which can inform the revision of welding guidelines and overall welded structure designs.

Effect of Shallow Cryogenıc Heat Treatment on Metal Inert Gas Weldıng Zone of S 355 J2 Steel

Metal inert gas welding (MIG) is generally conducted in the pressure vessel industry due to its high quality and easy automation. S355 J2 steel is used widely in this industry for its proper welding properties. To carry out and obtain high melting efficiency for satisfactory mechanical properties according to welding parameters, sometimes heat treatment is applied to materials, but generally it is not common in welding industry. In this study the effect of conventional heat treatment and shallow cryogenic heat treatment effects to the mechanical properties of welding zone of S 355 J2 steel welded with MIG is investigated. The charpy impact tests have been carried out. The welding plate is prepared according to this purpose and it is cut for impact test samples 10 X 10 x 55 mm. Totally 30 samples are prepared for 5 processes. Process 1: 6 samples for without heat treatment. Process 2: 6 samples for normalization-quenching in water. Process 3: 6 samples for normalization-quenching-tempering. Process:4 6 samples for normalization-shallow cryogenic treatment. Process 5: 6 samples for normalization-shallow cryogenic treatment-tempering. Notch of impact test samples are prepared just in the middle of the welding zone (2 sample for each process) , HAZ (2 sample for each process) and basemetal (2 sample for each process). The hardness values are taken from base metal, heat affected zone and welding area respectively. Hardness values and impact test results are compared. As a result, generally, it has been observed that shallow cryogenic heat treatment have a remarkable effect on toughness, despite a little decrease in hardness. The toughness of welding zone is increased approximately %40 and HAZ % 5 after cryogenic heat treatment. The hardness of WZ is increased approximately % 5 after cryogenic heat treatment, no significant change is observed in HAZ.

Investigation on Corrosion Behavior of Simulated Welding HAZ for 22 pct Cr Lean Duplex Stainless Steel With Different Mn/N Ratio Addition

Investigation on Corrosion Behavior of Simulated Welding HAZ for 22 pct Cr Lean Duplex Stainless Steel With Different Mn/N Ratio Addition

CHARACTERISTIC OF FRICTION STIR WELDING WELD JOINT OF AA 6061 ON INITIAL TEMPERATURE DIFFERENCE

Friction stir welding (FSW) is a solution to overcome the problems of AA 6061 welding. When the initial temperature T0 of the material is increased during the FSW process while the FSW process parameters are kept constant then FSW welding parameter value can be lowered. T0 was varied by Troom temperature, 50 0C, 75 0C, 100 0C and 125 0C. The weld joint design form is a square butt joint. By using this approach the higher the T0, with the FSW parameter being kept constant, produce the higher the welding peak temperature and cooling rate, the smaller and smoother the metal grain structure in the weld nugget, TMAZ and HAZ, the higher the hardness of the weld nugget and the higher the tensile strength eventough welding defects in the form tunneling, kiss bond, and void are still observed.

소형펀치시험에 의한 인코넬617용접부의 크리프거동 평가

In this research, the small punch (SP) test was applied to examine the local creep characteristics of a narrow gap weldment. To find the local creep property, an Ni-based 617 alloy and its narrow gap weldment. which is one of candidates for advanced fossil power plants, were employed. Thin square specimens were machined at three different locations: weld metal, base metal, and HAZ near the base metal from the Inconel 617 alloy narrow gap weldment. The results of the SPC test were evaluated. The microstructure of narrow gap weldment was observed by scanning electron microscopy and optical microscopy to investigate the effect of the microstructure on the creep properties of the weld zone. The creep rupture part of the weldment was observed by scanning electron microscopy. Finally, four different creep characteristics of the narrow gap weldment were obtained by the SPC test with good validity.

Pengujian Pengelasan Plat Stainless Steel JIS SS304 Menggunakan Mikro Struktur

Failure in the welding process will result in a drop in quality and a risk to worker safety. Small cavities were frequently detected during welding. In order to identify the origin of the damage, the goal of this study is to investigate the presence of small circular cavities that are grouped in the welding region of gas tungsten arc welding (GTAW) welding outcomes. The research technique involves categorizing changes in electric current on JIS SS 304 stainless steel material with a thickness of 10 mm: GTAW 80 A root (low current), 100 A Filler (mid electric current), and 120 A Capping (high current). Based on investigations into the use of electric current for Gas Tungsten Arc Welding (GTAW) welding and the interpretation of discontinuity in the outcomes of welding on JIS SS 304 stainless steel material, on JIS SS 304 plate material with a thickness of 10 mm. learn about the welding methods GTAW and HAZ GTAW at the point of the microstructure as components that have thermal impacts

Comparative study of SAW and ASAW process on ASTM A709 Grade 36 steel welds

Welding is a versatile fabrication process used in manufacturing industries for joining structural components. The welded structure's capacity to carrying loads is affected by bead characteristics and process parameters. In this research work, the influnce of the Submerged Arc Welding and Advanced Submerged Arc Welding process on heat input, area of penetration, reinforcement, and heat affected zone, electrode melting rate, electrode and plate melting efficiencies, flux consumption, metal deposition rate, the microhardness of weld metal and HAZ, the microstructure of weld metal zone and power consumption have been studied. The experiments were carried out with the bead on plate (BOP) technique in ASTM A709 Grade 36 steel. The Advanced Submerged Arc Welding process reduces the heat input and area of heat affected zone. At the same time, it increases the area of reinforcement height, electrode melting rate, electrode melting efficiency, metal deposition rate and flux consumption. The microhardness of both zones of the Advanced Submerged Arc Welding process is higher than the Submerged Arc Welding process. Moreover, the microhardness of the heat affected zone is higher than the weld metal zone. The microstructures show the ferritic structure with columnar grains, whereas the column size reduces in the Advanced Submerged Arc Welding process. The Advanced Submerged Arc Welding process reduces the power consumption by 20.59% compared to the Submerged Arc Welding process.

Ferrite in the HAZ of Dissimilar Temperature Probe Welds

Abstract Protector tubes for temperature sensors were welded onto experimental gas turbine compressor blades. While the blades were made of a high alloy hard-martensitic stainless chromium steel, a high alloy metastable austenitic stainless steel was used for the tiny protector tubes. The dissimilar weld joint was applied using manual GTAW. A large amount of blocky delta ferrite formed in the HAZ immediately adjacent to the fusion line, on the side of the martensitic steel. Delta ferrite in such dissimilar welds might detrimentally affect the mechanical properties of the weld joint. It was therefore recommended not to use the affected experimental blades in test engine service. Even though no failure occurred in this case, one was prevented by declaring the subject instrumented parts unfit for test engine service.

Chemical composition and weld cooling time effects on heat-affected zone hardness of line pipe steels

In the past few years, the pipeline industry in North America has faced a reported increase of pipeline girth weld failures predominantly in grade X70 pipe welded with cellulosic consumables. Weld strength matching and HAZ softening were two factors believed to have contributed to the concentration of strain during, or soon after, construction which ultimately lead to an overload failure of the girth welds. The work reported in this paper aimed to establish and clarify the correlation between steel chemical composition and the HAZ hardness in typical production girth welds and a range of weld thermal simulations. The first stage was to calibrate the influence of weld cooling rate of both thermal simulations and real welds in steels over a wide range of chemical composition, typical of commercial high strength API pipe. Second, the influence of Pcm, carbon content, Mo content and cooling time in terms of minimum and maximum hardness were investigated. The comparison between simulated HAZ's and real welds showed that thermal simulation produces samples that adequately duplicate the real condition in terms of maximum and minimum hardness and can accurately assess both hardening & softening which occur in different regions of the HAZ. The simulated samples provided increased areas of different HAZ regions in order to more accurately identify the range of hardness values across the HAZ which was then correlated to real weld hardness profiles. It is concluded that ultimate hardness in the HAZ is directly related to steel chemical composition in terms of Pcm and weld cooling rate. It is however apparent that the relative percentage change in hardness from the original parent pipe hardness (also called % HAZ softening), which is important in determining the strain capacity of the weld joint, is principally dependent upon steel processing, especially the degree and severity of thermomechanical processing. This is evident by the fact that same API pipe grades have a wide range in chemical composition and most importantly Pcm, and the response to field welding conditions can be quite different depending on weld heat input, pipe wall thickness and preheat, all of which define the weld cooling rate.

EFFECT OF DIFFERENT MIG WELDING MODES ON HARD-FACING OF INCONEL 718 ON 321 STAINLESS STEEL

In this study, the metal inert gas (MIG) welding process is taken to deposit the Inconel 718 material on 321 stainless steel. Various modes like the DC, DC-pulsed, and DC-wave-pulsed modes in MIG welding are used for depositing Inconel 718. The primary parameters such as the welding current (90–120 A) and speed (150–350 mm/min) are varied within the range for making the layer deposition over 321 stainless steel. After performing the layer deposition, the dilution, contact angle, and peak temperature are analyzed to find the optimal MIG welding mode. From the macrograph, very low dilution (7.44%) is identified for the DC mode. The most inferior contact angle ([Formula: see text]) of 49° was measured for the DC-wave-pulsed mode. The simulation work predicted a peak temperature of 2800°C for the DC mode. Considerable microstructure changes have occurred at the weld deposition (dendritic structure) and HAZ (grain coarsening) for all the three modes. At the top, interface, and HAZ locations, the microhardness obtained from the DC-pulsed mode is in between those of the DC and DC-wave-pulsed modes. Overall, the DC-pulsed mode is qualified for making the metal deposition and further work. For 50% overlap, defect-free 2-mm-thick layer depositions are made on the 321 stainless steel surfaces.

Studies Regarding FCAW Welding of Dissimilar Joints between Duplex Stainless Steel and Naval Carbon Steel

In this paperwork is presented a study of dissimilar welding with FCAW welding process, between duplex stainless steel S31803 (1.4462) and naval carbon steel EH36 (1.0546), being analyzed all the considerations related to their weldability, resulted mechanical properties, microstructure and evaluation of the toughness and hardness of the weld seam and HAZ area.

Microstructure Changes related Mechanical Properties of Welded HSLA Steel Plates

Strength and toughness of steel are the most desirable mechanical properties required in several engineering applications such as marine and oil industries. In this work, the influence of submerged arc welding (SAW) process on the evolution of microstructure and mechanical properties of locally produced low carbon steel plates that is used by Marine Industry and Maintenance Company (Misurata) as an alternative to the imported marine steel plates is investigated. Microstructure investigation, tensile tests, impact toughness, and hardness tests for both steels are conducted. Results show that microstructure is affected by the heat input of SAW leading to more uniform structure of ferritic-bainitic and finer grain sizes. Inherently, affecting the mechanical properties since a decrease in toughness in the heat affected zone HAZ and weld metal zone WM compared to the parent metal is observed. It is shown that the imported steel has higher toughness than local steel for pre-welded and welded plates, with imported steel offering significant reduction in toughness when subject to welding. The effect of welding can be related to the microstructural changes of the weld metal and HAZ attained by adapting proper consumable electrode and welding process strategies.

Evaluation of Microstructural and Mechanical Behavior of AHSS CP780 Steel Welded by GMAW-Pulsed and GMAW-Pulsed-Brazing Processes

Joints of complex phase 780 (CP-780) advanced high strength steel (AHSS) were carried out by using an ER-CuAl-A2 filler metal for the gas metal arc welding pulsed brazing (GMAW-P- brazing) process and the ER-80S-D2 for the GMAW-P process employing two levels of heat input. The phases in the weld bead and HAZ were analyzed, and the evaporation of zinc by means of scanning electron microscopy (SEM) was also monitored. The mechanical properties of the welded joints were evaluated by tension, microhardness and vertical impact tests. It was found that there was greater surface Zn evaporation in the joints welded with the GMAW-P process as compared to the GMAW-P-brazing process. The best results in tensile strength were observed in the joints welded with GMAW-P-brazing process, which increased by ~68% with respect to those of the GMAW-P. This behavior can be attributed to the formation of an intermetallic complex compound Cu-Al-Fe in the fusion line.

EFFECT OF WELD HEAT INPUT ON THE MECHANICAL CHARACTERISTICS OF Cr-Mo STEEL BARS USING THE MIG WELDING PROCEDURE

The impact of weld heat input on the mechanical characteristics of this steel was investigated in this study. The weld sample was an ASTM A304 grade A Flat Bar with a thickness of 5.00 millimetres. With the use of a data logger, a K-type thermocouple was installed in the drilled holes to measure the temperature fields at each of the places throughout the welding operation. The welding sample was created by varying three process parameters in the MIG welding process. Welding current, weld passes, and point of interest thermocouple position away from the weld centreline are the parameters. The experiment was designed using Taguchi's L9 orthogonal array to limit the number of experimental runs (DOE). To study the influence of weld heat input, the samples were subjected to mechanical and microstructure testing. The hardness test revealed that when the weld pass on the weld zone, HAZ, and base metal increases, the hardness value falls. The tensile test finding indicated that the tensile strength of samples 80A and 100A rises as the weld pass increases, however sample 60A decreases as the weld pass increases. The impact resistance increased when the weld pass was increased, according to the findings of the impact tests. The distance away from the weld centreline of the region subjected to a certain peak temperature increases as weld heat input increases, according to the weld thermal cycle. The value of the temperature fields increases dramatically as the heat source passes through the specific cross-section, where thermocouples are positioned. Later on, the temperature begins to drop at a slower rate. It's also obvious that when the distance between the measurement point and the weld centreline grows, the temperature drops.

Study on corrosion behavior of high nitrogen steel welded joint assisted by ultrasonic vibration

In this paper, the corrosion behavior of weld seam and HAZ in high nitrogen steel laser-arc hybrid welded joint was studied. By the assistance of ultrasonic vibration, the optimization effect of microscopic corrosion in different weld zone were compared. By electrochemical corrosion tests, it was found that the weak HAZ obtain greater performance improvement. The cavitation effect homogenized the corrosion traces of the weld seam in the form of dendrites refinement. And the ultrasonic vibration inhibited the extreme interfacial corrosion behavior at interface of HAZ and base metal. The welding pool crystallizes into finer grain structure and forms a stable moderating zone at the interface of heterogeneous metallography.