Effect Of Post-weld Heat Treatment Research Articles

Effect of post-weld heat treatment on the microstructure, phase composition and mechanical properties of dissimilar Al-Mg-Li/Al-Cu-Li laser welded joints

Butt joints of the V-1461 and 1424 heat treated aluminum–lithium alloys of the third generation were welded with a CO2 laser and studied in detail for the first time. In particular, spatial distributions of the formed phases and their evolution upon post-weld heat treatment (PWHT), determining the mechanical properties of the joints, were investigated. The PWHT included quenching and subsequent artificial aging. The key factors, affecting the metallurgical processes in a weld pool, were the following: 1) the alloying elements and the thermal properties of the alloys, 2) the dynamics of the local non-equilibrium melting, the convective transfer of the molten metal in the weld pool and its subsequent solidification, 3) the cooling rate, and 4) the PWHT procedure. By using synchrotron radiation and scanning electron microscopy, new θ(Al2Cu), T1(Al2CuLi) and S1(Al2MgLi) phases were found in the weld metal that were absent in both base metals. This phenomenon reduced the mechanical properties of the joints to the levels, corresponding to about 50 % of the 1424 alloy as the weakest one. Quenching contributed to the formation of the δ′(Al3Li) strengthening phase in the weld metal. As a result, the ultimate tensile strength increased up to 70 % and elongation up to 95 % of the corresponding levels of the 1424 alloy. Artificial aging made it possible to form the T1(Al2CuLi) strengthening phase, to increase the content of the δ′(Al3Li) one, as well as to improve the mechanical properties of the joint. In this case, the ultimate tensile strength was 411 MPa, the yield point was 327 MPa and elongation was 1.7 %. These values were close to those for the 1424 alloy (about 80 %, 89 % and 23 %, respectively).

Effect of post-weld heat treatment on mechanical and microstructural properties of high strength steel weld metal

The usage of high strength steel (HSS) is steadily increasing, primarily driven by the pursuit of weight reduction, leading to a subsequent decrease in greenhouse gas emissions. This paper investigates the impact of various post-weld heat treatment (PWHT) temperatures of 525 °C, 550 °C and 575 °C with a holding time of 2 h on both the microstructure and mechanical properties of weld metal produced using a HSS metal cored wire. The investigation reveals that PWHT does not significantly alter strength but has a more pronounced influence on toughness. The as-welded condition exhibited the highest toughness. Among the samples subjected to the PWHT, the one treated at 575 °C showed the highest impact energy, reaching 69 J at −60 °C. This outcome is attributed to the increased presence of acicular ferrite in the microstructure, surpassing that of samples subjected to PWHT at different temperatures.

Effect of Post-weld Heat Treatment on Microstructure and Mechanical Properties of P91 Heat-Resistant Steel Coating on Mild Steel

Effect of Post-weld Heat Treatment on Microstructure and Mechanical Properties of P91 Heat-Resistant Steel Coating on Mild Steel

Effect of Post-weld Heat Treatment on the Microstructure and Mechanical Properties of 2.25Cr-1Mo-0.25V Ultra-Thick Steel Plate

Effect of Post-weld Heat Treatment on the Microstructure and Mechanical Properties of 2.25Cr-1Mo-0.25V Ultra-Thick Steel Plate

Microstructure and Fatigue Behavior of Cr-Mo Steel Weld Joints with Automatic TIG Welding

This research focused on how filler metal and post-weld heat treatment (PWHT) affected the microstructure and mechanical properties of 2.25Cr-1Mo steel welds, especially the fatigue behavior. Automatic TIG welding was used to fabricate the weld samples, and both AWS A5.28 ER90S-B3 (also known as B3) and AWS A5.14 ERNiCrMo-3 (commonly known as Inconel 625) were used as filler metals. The PWHT was performed at 690°C for one hour. That was the ideal condition for reducing the hardness of the heat affected zone (HAZ). The microstructure of the B3 weld metal and the HAZ was observed to alter from bainite to tempered bainite due to PWHT, resulting in a decrease in hardness (B3 WM: from 299.7 to 243.5 HV0.2 and HAZ: from 294.5 to 234.7 HV0.2). On the other hand, Inconel 625 weld metal showed an austenite microstructure: after PWHT, the formation of gamma prime increased its hardness (from 263.2 to 299.8 HV0.2). According to the tensile test results, the tensile strength of the welded samples was slightly lower than that of the original base metal, such as the UTS of the BM was 633.0 ± 3.0 MPa and that of the B3-PWHT sample was 601.4 ± 2.0 MPa. The effect of PWHT on tensile strength was negligible, but it significantly affected fatigue strength. For both filler metals, PWHT resulted in a decrease in fatigue strength. The fatigue strength of the B3 sample decreased from 290 to 120 MPa, while that of the IN625 sample reduced from 290 to 240 MPa. In comparison between two different materials, the fatigue strength of the Inconel 625 sample was greater than that of the B3 sample. Fatigue fracture surfaces can be classified into three stages: crack initiation, propagation, and fast fracture. The fatigue rupture was mostly initiated at the weld interface. The final fracture revealed a dimple appearance.

Effects of post-weld heat treatments in microstructure, mechanical properties, and corrosion resistance of simulated heat-affected zone of supermartensitic steel UNS S41426

Effects of post-weld heat treatments in microstructure, mechanical properties, and corrosion resistance of simulated heat-affected zone of supermartensitic steel UNS S41426

Effect of post-weld heat treatment on corrosion resistance of X90 pipeline steel joints

Abstract In order to improve the corrosion resistance of welded joints, X90 pipeline steel joints were subjected to post-weld heat treatment at 610 °C, 640 °C, and 670 °C (holding time was 1 h). Through electrochemical corrosion and full immersion corrosion experiments, the corrosion resistance of welded joints under various conditions was tested, and the surface morphology and corrosion products of the corroded samples were analyzed by scanning electron microscopy and X-ray diffraction analysis. The experimental results show that the corrosion products of X90 pipeline steel welded joints in simulated soil solution mainly include Fe(OH)3, γ-FeOOH, α-Fe2O3, γ-Fe2O3, and a small amount of Fe3O4, FeCl3 and Fe. After heat treatment at 610 °C, the corrosion current density of the parent metal, heat-affected zone, and weld metal of the joint changes from 1.081, 2.889, 2.079 (×10−5 A cm−2) to 0.977, 2.211, 1.810 (×10−5 A cm−2), respectively, the corrosion resistance is improved.

Dissimilar friction stir welding and post-weld heat treatment of Ti-6Al-4V and AA7075 producing joints of unprecedented strength

Dissimilar welding of Ti and Al alloys is challenging due to the potential formation of brittle intermetallics, which can compromise weld strength. Friction stir welding (FSW) is an advanced joining method with the potential to drastically reduce or prevent the formation of intermetallic phases because melting is avoided. However, in previous studies, dissimilar joints of Ti-6Al-4V and EN AW-7075 with satisfactory strength could not be achieved. Thus, we investigated friction stir welding of these two materials in a butt configuration, and analyzed the effects of post-weld heat treatments on the mechanical properties. Tensile strengths of 441 MPa in the as-welded condition and 505 MPa after heat treatment were achieved, significantly surpassing strength values reported in earlier studies. Microscopic investigations showed no evidence of formation of brittle intermetallic phases, and ductile fracture was observed. Our results show that FSW is a very promising candidate for future aerospace applications requiring dissimilar joining of Ti and Al alloys.

Influence of Ni and PWHT on microstructure evolution and mechanical properties of GTA-welded duplex stainless steel and super duplex stainless steel joints: A comparative investigation

In the present investigation, a new endeavor has been made to analyze the impact of the secondary process (post-weld heat treatment (PWHT)) as well as Ni addition on the microstructure and mechanical characteristics of welds. Welds between similar joining materials from duplex stainless steels (DSS), as well as super DSS (SDSS), were made by the gas tungsten arc welding (GTAW) process. For DSS, after PWHT with the addition of Ni element, the amount of austenite rises and becomes more uniformly distributed with curved boundaries, while for SDSS, the microstructure mainly consists of intergranular and Widmanstätten austenite. According to the comparison of phase percentages obtained based on both ASTM E1245 and ASTM E562, a good balance between ferrite and austenite phases of joint materials was achieved. X-ray diffraction analyses on both joints revealed that phases are mainly ferrite and austenite with different lattice parameters without evidence of unwanted intermetallic phases. The addition of Ni increases the hardness values of DSS weld metal compared to the base metal due to an increased amount of Widmanstätten austenite and ferrite in the microstructure. The lowest ductility was obtained for the SDSS weld sample with the addition of Ni and PWHT because of the existence of secondary austenite in the weld metal and the Widmanstätten morphology of the austenite. The effect of PWHT on the development of microstructure and mechanical behaviors was more than the effect of nickel powder on weld samples.

Postweld Heat Treatment on Toughness of Electric- Resistance Welded X70 Steel

The effect of postweld heat treatment (PWHT) on Charpy V-notch impact toughness of a highfrequency electric-resistance welded (HF-ERW) grade X70 pipeline steel is investigated. PWHT thermal cycles are simulated using the Gleeble on the as-welded specimens. Microstructure, along with crystallographic texture and microhardness, is characterized in specimens that are impact tested at –5°C (23°F), –30°C (–22°F), and –45°C (–49°F). The impact toughness values show a wide scatter band and decrease with the increasing peak temperature of the PWHT. For higher peak temperatures, the microstructure of the heat-affected zone (HAZ) gradually changed from equiaxed ferrite to bainitic ferrite. Furthermore, the prior austenite grain size (PAGS) increases with the increasing peak temperature. The density of high-angle grain boundaries decreases, and the fraction of cleavage planes {100} parallel to the impact fracture plane increases for higher peak temperatures of the PWHT.

Effect of post-weld heat-treatment and solid-state thermomechanical treatment on the properties of the AA6082 MIG welded joints

Post-weld heat treatment (PWHT) and solid-state thermomechanical treatment (TMT) via friction stir processing (FSP) have been shown to enhance the mechanical properties of aluminum alloys. The current work investigates the effects of PWHT and TMT on the microstructure and mechanical performance of AA6082-T6 welded butt joints welded using the MIG process. The 5 mm thick AA 6082-T6 plates were joined in butt configuration using MIG welding with ER 5356 filler wire, 120 A current, 0.3 mm/s weld speed, and argon shielding gas at 15 L/min flow rate. PWHT was performed on the MIG welds per the T6 temper procedure. TMT was implemented via FSP using a pinless tool rotating at 800 rpm and traversing speed at 200 mm/min with a 3° tilt angle. Microstructural analysis, hardness mapping, tensile testing, and fracture surface evaluation were utilized to characterize the as-welded, PWHT, and TMT samples. The results demonstrate that both PWHT and TMT significantly refine and homogenize the microstructures of the welded joints. However, the TMT samples displayed superior hardness and tensile strength compared to the as-welded and PWHT conditions. The TMT-processed welds achieved approximately 99% joint efficiency versus only 69% and 85% for the as-welded and PWHT samples. In summary, PWHT and especially TMT via FSP are effective at enhancing the mechanical properties of MIG welded AA6082-T6.

Effects of post-weld heat treatment on the microstructure and properties of the matching SMAW filler metal for weld joints in MarBN steel

AbstractA detailed investigation has been carried out of the matching composition filler metal for welding MarBN steel to explore the influence of welding procedure and post-weld heat treatment (PWHT) on the microstructure and properties of the weld metal and a MarBN steel weld joint. The filler metal was in the form of a shielded metal arc welding (SMAW) electrode. With different interpass temperatures and PWHT procedures applied, the microstructure and mechanical properties, particularly toughness, of the all-weld metal deposits and welded MarBN alloy joints were examined. The differences in microstructure (grain structure, precipitates, etc.) were evaluated to provide a better understanding of how the PWHTs influence the starting conditions of the matching weld metal and welded MarBN steel joints before service. The current work found that for a 30-mm-thick all-weld metal coupon, reasonable impact toughness was achieved after PWHT of 735 °C × 8 h; longer heat treatment durations (16 h and 36 h) did not further increase the toughness. For thicker cast blocks, a PWHT of 735 °C × 16 h was needed for weld toughness comparable to the base metal, hence was considered more appropriate for actual engineering applications. Evenly distributed Laves phase precipitation was observed after 735 °C × 8 h; the precipitates gradually increased in size and area fraction as the duration increased, and appeared to be stable when approaching 36 h. Differences in the precipitation were observed between different weld regions. The weld cap region had a lower density of Laves precipitates compared to the lower weld area. From the current investigation, aspects for further investigation are also identified.

Effect of post-weld heat treatment on microstructure, crystallography, and mechanical properties of laser beam welded AISI 904L super austenitic stainless steel

This research examines the crystallography, microstructure, and mechanical properties of AISI 904L super austenitic stainless steel (SASS) joint by laser beam welding (LBW). The results indicated that the B3 and B4 specimen’s weld metal (WM) microstructure (the minimum value at the welding heat input of 0.117 kJ/mm and the maximum value at the welding heat input of 0.200 kJ/mm) comprised almost all austenite (dendritic + interdendritic) phases. Some Cr23C6 and Cr2N precipitates appeared at the grain boundaries and in the interdendritic region due to post-weld heat treatment (PWHT). Besides, it was obtained that the dendritic structure increased due to the rise in heat input. While most of the grains in WM displayed orientation in [111] and [101], it was detected that they displayed orientation in [001] and [101] with PWHT. While the high-angle grain boundary (HAGB) ratio of the B4 specimen was found to be high, the low-angle grain boundary (LAGB) ratio of the B4H specimen was found to be also high. In addition, the KAM was reduced with the effect of PWHT. Kurdjumov-Sachs (K-S) and Nishiyama-Wasserman (NW) orientation between grains with FCC/BCC structure was observed in WMs of B4 and B4H specimens. The highest mechanical properties were mostly obtained in the specimens joined by the lowest welding heat input. Fracture surfaces of tensile and impact samples of laser welded joints showed mixed mode fractures, i.e. ductile and partially cleavage fractures.

Effect of post-weld heat treatment on heat affected zone microstructure of additively manufactured Inconel 718

Laser powder bed fusion for metals is a method of producing end use components for industrial use. Powder bed fusion machines are relatively small, and are usually used to create only the critical part of the larger assembly. Therefore, L-PBF manufactured parts must be attached to each other for example by welding. The industrial world needs to be able to join the printed superalloy components to the traditionally manufactured components to reach better corrosion, wear and/or heat resistance in selected parts in an assembly. The problem is that there is limited amount of information about the suitable welding parameter values for these applications. This study examines how the standard heat treatment cycles affect to the quality of the weld, and if the post-heat treatment is reducing undesired phases in the heat affected zone. Test has shown that post heat treatment highlights cuboidal shaped niobium rich carbides throughout the material to the heat affected zone grain boundaries.

Effect of post-welding heat treatment on microstructure and properties of electron beam welding joint of new high-strength TB18 titanium alloy

Effect of post-welding heat treatment on microstructure and properties of electron beam welding joint of new high-strength TB18 titanium alloy

Post-weld heat treatment effects on microstructure, crystal structure, and mechanical properties of donor stir–assisted friction stir welding material of AA6061-T6 alloy

Post-weld heat treatment effects on microstructure, crystal structure, and mechanical properties of donor stir–assisted friction stir welding material of AA6061-T6 alloy

Effect of PWHT on metallurgical and mechanical characterization of dissimilar welded joint of P91 and P92 steels

P91 and P92 steels are widely used in nuclear and thermal power plant’s high-temperature (650–700 °C) operating components. The welding procedure, base plate composition, filler material composition, and post-weld heat treatment (PWHT) significantly affect the metallurgical characterization of weldments at room temperature. This work focuses on joining P91 and P92 steel by the TIG welding with filler ER90S-B9. The study analyzes the materialization of coarse-grained HAZ (CGHAZ), inter-critical HAZ (ICHAZ), and fine grained HAZ (FGHAZ) under welded and PWHT. PWHT was conducted at 840 °C for 2, 4 and 6h. An optical microscopic (OM) scanning electron microscope (SEM) was employed to characterize the welded and PWHT samples. It was perceived that the tensile strength of PWHT increased as the heat treatment times increased from 2 to 6 h, while the hardness value decreased accordingly. The maximum tensile strength (594.71 MPa) was observed in PWHT_6 h, while the minimum tensile strength (537.52 MPa) was perceived in the as-welded sample. The PWHT_6h reveals the minimum hardness values (271.12 HV) at the fusion zone among all the conditions. The WFZ consisted of an untampered lath martensitic grain structure, demonstrating an average hardness value of 314.15 HV in the PWHT_2h condition. The hardness value in CGHAZ samples for as-welded, PWHT_2h, PWHT_4h, and PWHT_6h was observed at 456.85, 436.81, 368.63, and 327.41 HV, respectively.

Effect of post-weld heat treatment on mechanical properties and microstructure in electric arc welded mild steel joints

Mechanical and microstructure properties of weld joint between mild steel plates before and after heat treatment process have been studied. In this study, electric arc welding was used as a welding method as it is the most common welding method. Then heat treatment of the samples were done in the furnace. Firstly, in the heat treatment process, stress annealing was done as stress generated at different places in the welding zone and after that full annealing was done using furnace cooling for cooling purpose. Tensile strength was measured using ASTM A370 standard specimen and Brinell hardness test was done at different surfaces of the welding zone. The microstructures were observed by cutting the specimen in a certain shape, and mirror surfaces were generated to observe in electron microscope. From the results, it was observed that PWHT causes a 4.1 % increase in tensile strength, a 13.84 % gain in yield strength, and a 4.96 % rise in percentage elongation. However, the value of hardness decreased 19.19 % after heat treatment as heat treatment increased the ductility of the specimen. At the place of the Electric Arc Welding joint, a smaller grain size, a lower gap between the grains, and comparatively few voids were identified.

Effect of Post-Weld Heat Treatment on the Microstructure and Mechanical Properties of ERNiCrMo-3 Weld Metals

Effect of Post-Weld Heat Treatment on the Microstructure and Mechanical Properties of ERNiCrMo-3 Weld Metals

The Effects of Post-Weld Heat Treatment on the Microstructure and Mechanical Properties of 9% Ni Steel Weld Joint with Fe-Based Filler Material

A Fe-based filler material with the composition of Fe-20Ni-5Co-2.5Mn-0.2C was used for welding 9% Ni steel, and the effect of post-weld heat treatment on the microstructure and mechanical properties of the welded joints was investigated. Post-weld heat treatment of the welded joint was performed in the temperature range of 200 to 600 ℃. After the experimental selection, the microstructure changes of the weld metal and base metal were investigated in detail at heat treatment temperatures of 350 and 600 ℃. Grain morphology, size, and the location of precipitated cementite were studied using SEM and EBSD phase maps. The mechanical properties of the weld joint were characterized by tensile properties and micro-hardness. Based on the experimental results, this study provides key insights into the applicability of post-weld heat treatment to weld joints of 9% Ni steel prepared using Fe-based filler material to improve the mechanical properties, toughness and ductility of the weld joints.