Parent Metal Research Articles

Welding, mechanical properties and microstructure of different grades of austenitic stainless steels: A review

Nowadays the power of the industry standard materials has gained a lot with the advancement in technology. The requirement for materials with high creep rupture strength, high thermal conductivity, and strong corrosion resistance rose dramatically when the power plant was operated at greater temperatures and pressures. Creep strength improved steels, nickel based alloys, and austenitic stainless steels are the most often utilised materials in high temperature and high pressure power plants. To meet the strength criteria, reduced cost investment, and service standards must be met, dissimilar welding between Stainless steels is required. This necessitates the combining of different metals. An effective weld among different metals is one which is as strong as that of the weakest of the two different metals being connected, that is, it has enough ductility and tensile strength to prevent the junction from failing during the weld. Such joins may be made from a number of metals and using a range of welding methods. Before selecting the best way to join the metals the evaluation of both the base metals and the filler material is to be done. Here the welding process done between steels is TIG welding. Challenges in the current research are to join the different materials without disturbing the properties of parent metals. Some of the frequently occurring problems are: wider HAZ (heat affected zone), Difference in coefficient of thermal expansions, Difference in chemical composition, Multi pass welds to weld high thickness materials. Current research deals with the Optimization the TIG Welding Process and To Understand the effect of Process Parameters on Mechanical Characteristics of the dissimilar joints and to carry out Numerical Investigation on the dissimilar welding of Austenitic Stainless Steel.

Effect of Tool Pin Geometry and Process Parameters During FSW of Dissimilar Alloys of Mg

Effect of two distinctive tool designs along with other tool related parameters including speed of traverse of tool and offset distance of tool pin during friction stir welding of dissimilar AZ91C and AZ31B alloys of Mg were investigated. Experimental recordings revealed that all the joints fabricated during 1st set of investigations employing cylindrically tapered pin geometry and their offset distances being 0.5 mm or 1mm towards any one of the parent metals possessed flaws. Joint No: II-3 fabricated in 2nd set of investigations by employing 15mm diameter inner shoulder tool with threaded cylindrical tapered pin geometry at a tool offset distance of 0 mm was found be free from flaws. This joint exhibited a tensile strength of 186 MPa which was 78.81% of AZ91C and 70.72% of another parent metal AZ31B. Existence of intermetallic phased constituents, namely, Mg17Al12 in several regions of fractured surfaces have contributed to the supplementary brittleness in the zone of nugget, and have reduced the tensile strength of the joint.

Comparative studies on weldability and mechanical characteristics of semi- killed steel using different arc welding technique

The main objective of this study is to examine the weldability and mechanical properties of semi-killed steel of E250BR grade which is mostly used in gear box casing. Three different arc welding methods i) GMAW (Gas Metal Arc Welding) ii) GTAW (Gas Tungsten Arc Welding), and iii) A-GTAW (Activated Gas Tungsten Arc Welding) were employed in this study, and the respective weld joints mechanical properties were evaluated and compared with each other. Visual inspection of the specimens shows that the GTAW and A-GTAW processes offer excellent weld bead geometry. Visual and radiographic inspections showed no crack or discontinuity is in the weld joints. The weldment produced by A-TIG welding has the highest aspect ratio, which is due to the reverse Marangoni convection effect. The tensile and hardness test outcomes exhibited that the mechanical properties of the parent metal were not affected by the welding processes, but impact test results showed a lack of energy absorption by the specimen from the A-GTAW process. A-GTAW welding had the highest Ultimate Tensile strength, which was 2.5 percent to 5 percent higher than the other processes employed in this study. Weldments fabricated using GTAW welding have the highest impact toughness, which is 43.5 percent and 51.85 percent more than the other two processes. Vickers hardness test reveals that joints made with the GTAW process are better than the other counter parts.

Исследование влияния параметров режима сварки трением с перемешиванием меди на механические свойства и электропроводность сварных соединений

Copper is widely used when producing current-conducting parts, basically the electrotechnical power equipment buses. Traditional ways of welding copper become complicated because of high thermal conductivity, fluidity, significant oxidation at fusing temperature, and susceptibility. The application of the solid-phase welding methods, a prominent representative of which is friction stir welding (FSW), is one of the ways to solve problems when welding copper. The paper presents the experimental study of the influence of a tool working part shape and the welding mode parameters: welding rate, tool rotation frequency, and tool dip angle – on the possibility of the appearance of defects in welded joints of M1 copper plates of 5 mm in thickness produced by FSW. The paper contains the results of mechanical tests on static tension and bending of welded joints with a tunnel defect and without it. Welded joints with a tunnel defect showed a decrease in mechanical properties level: the value of ultimate tensile strength at stretching is lower by 33 %, and the specific elongation is lower by 8 % than ones of a joint without defects. The authors specify some factors influencing the appearance of defects at FSW: the welding rate, tool rotation frequency, tool working part construction, tool dip angle, strength and depth of immersion, pin displacement, blank thickness, and grip conditions. The study identified that the application of a tool with a concave surface taper shoulder allows producing welded joints without external and internal defects. Based on data obtained during the experimental research, the authors determined the welding modes, which makes it possible to produce welded joints with the electrical resistance value at the level of a parent metal: tool rotation frequency is 1250 rpm, welding rate is 25 mm/min, and tool immersion depth is no less than 0.41 mm.

Influence of Different Frequency Pulse on Weld Bead Phase Ratio in Gas Tungsten Arc Welding by Ferritic Stainless Steel AISI‐409L

The objective of the present experimental work is to obtain an appropriate welding parameter on pulsed current gas tungsten arc welding (GTAW) ferritic stainless steel AISI 409L with a thickness of 4.5 mm. Frequency affected penetration, and the ratio of bead width to penetration (aspect ratio) is the main objective of the research. A Taguchi L9 orthogonal array with three level four factors was chosen to execute the bead on plate welding. It leads to optimize the input process parameters on main effect plot via analysis of variance, and it has imposed to determine their contribution level of each parameter with respect to responses. Taguchi optimized conditions for butts weld with the pulsed TIG and its surface morphology, and mechanical characteristics of AISI 409L weld was investigated. A full penetration with an optimal aspect ratio was accomplished using high‐frequency pulsing, according to the findings. The mechanical properties were characterized using Vickers microhardness and tensile tests on the base material and weld metals. Microstructural study revealed that these variables have a greater impact on the bead profile. Pulsed TIG showed maximum UTS of 445 MPa and a minimum of 385 MPa, with an average of three samples of 415 MPa. The weld metal in all of the zones had influenced superior tensile strength (UTS) as compared to base metal, according to the findings. The obtained strain percentage for both butt and TIG welds, however, was smaller than that of the parent metal. The formation of martensitic was attributed for the higher tensile strength with minimized ductility of the pulsed TIG welds. Furthermore, results on the hardness are in concurrence with the tensile experiments, as the zone for fusion has a higher hardness than the base metal. Corrosion behavior of the parent metal and welded specimen was analyzed using a potentio‐dynamic polarization technique. The electrochemical behavior of base material and weld samples confirmed that the overall corrosion resistance is better in parent material than the other zones.

Dissimilar joining of different grades of ferritic stainless steel: A review

In the recent times the power of the industry standard materials has gained a lot with the advancement in technology. To run the power plants at a required temperature and pressure, the demand for the material with high strength, high thermal conductivity and high corrosion resistance increased significantly. The large number of materials that are mostly used in power plants which are operating at high temperature and high pressure are creep strength enhanced steels, nickel based alloys and austenitic stainless steels. To fulfill and to satisfy the strength requirements, lower cost investment and service conditions, dissimilar welding between Stainless steels is required. And here we can see how important is the need joining dissimilar metals in such cases. A successful joining of two dissimilar metals is as strong as the weaker of the two metals being joined using different welding techniques, i.e., having enough and sufficient tensile strength and ductility so that the joint will not fail in the weld. These joints can be used in a variety of different metals and by several welding processes. The filler material and both metals need to be evaluated before choosing the best way to connect the metals. Here the welding process done between steels is TIG welding. Challenges in the current research are to join the different materials without disturbing the properties of parent metals. Some of the frequently occurring problems are: wider HAZ (heat affected zone), Difference in coefficient of thermal expansions, Difference in chemical composition, Multipass welds to weld high thickness materials. Current research deals with the Optimization the TIG Welding Process Parameters using RSM (Response surface Methodology) and To Understand the effect of Process Parameters on Mechanical Characteristics of the dissimilar joints and to carry out Numerical Investigation on the dissimilar welding of Ferritic Stainless Steel by joining the different materials using tungsten inert gas welding.

CHARACTERIZATION OF WELD HEAT INPUT EFFECTS ON MECHANICAL PROPERTIES OF Cr-Mo STEEL BAR USING TIG WELDING PROCESS

Welding as an energy-consuming process is inevitable as-welded joint can be subject to various loads without failure. Therefore, this paper presents the welding thermal cycle of Cr-Mo steel bar (ASTM A304) of dimensions 100 by 50 and various thicknesses of 5, 10- and 15-mm. Pure tungsten with 2% thoriated TIG electrodes sizes 1.6 mm X 175 mm, 2.4 mm X 175 mm, and 3.2 mm X 175 were used without filler materials for the welding process. A double V-groove weld joint, with a moving heat source, was employed to determine the temperature fields and transformation in the single-pass butt-welded joint. A calibration process was attached at each point of interest using a datalogger type K-type thermocouple 3-channel–LU-MTM-380SD during the welding process on the Cr-Mo steel bar. The results showed that the welding temperature became higher at the welding centreline and decreased towards the edges of the bar. An indication that a weld thermal cycle is a veritable tool, a function of heat input to access likely consequence of the welding process at both welded and parent metal portions of steel bar. Design of Experiment using Taguchi L9 orthogonal array matrix L9(3^4), Factors:4 and Runs:18 in Minitab 17 Taguchi Design Method that suited the experimental method used. Taguchi’s L9 orthogonal array to restrict the number of experimental runs was used for the design of the experiment (DOE). Mechanical and Microstructure tests were carried out on the samples to investigate the effect of weld heat input. The hardness test result showed that samples C15 and D15 have the highest hardness values 165.0HV and 164.0HV respectively at Base metal (BM) 20mm away from weld centreline and it was also observed that samples C15 and D15 have the highest impact values 48.53J and 48.7J respectively. The microstructure of the C15 at the weld zone WZ, which consists majorly of pearlite and less ferrite, BM shows the appearance of alpha ferrite and pearlite and heat-affected zone HAZ consists majorly of pearlite and a very small proportion of ferrite resulted in increased hardness and impact values at the HAZ.

High strength low-alloy steels impact toughness assessment at different test temperatures

In many production processes, as well as in the exploitation of machine components and structures, materials are exposed to impact loads. In structures made of welded joints of high strength low-alloy steels with their constituents (parent metal, weld metal and heat-affected-zone), the toughness test determines the tendency of steel to brittle fracture, respectively the tendency to increase brittleness during exploitation. The strain rate is high and the material manifests much more brittle behavior than is shown by tensile testing. Toughness as a mechanical property is an important factor that is defined as the energy that needs to be spent in order to achieve fracture. Parameters obtained by testing the properties of plasticity are the basis for the design of structures in order to achieve strengths under applied load. The test results of high strength low-alloy steel toughness assessment at different test temperatures show that temperature significantly affects the impact toughness of steels and their alloys. At higher temperatures the impact energy on fracture is high (the material shows the properties of plasticity) while at lower temperatures the impact energy is small (the material is brittle).

Investigation into novel multipass friction stir vibration brazing of carbon steels

ABSTRACT In this examination, an advanced version of friction stir brazing (FSB) entitled friction stir vibration brazing (FSVB) was implemented to produce a joint between low carbon steels. %67 wt Sn-%33 wt Pb alloy was used as brazing metal. This article aims to study the effect of mechanical vibration and brazing pass number on the structure and mechanical behaviors of the brazed samples. In addition, the thermal analysis, the characteristics of intermetallic compounds (IMCs) layers, and void volume percentage at the bond interface were investigated. It was found that the coherency of the joint interface increased as the brazing pass number increased. Additionally, the mechanical performance, namely, shear strength and hardness of brazed samples enhanced as the vibration was applied during FSB, and brazing was done in two passes. The results showed that the metallurgical reaction between the parent metal and the filler enhanced as FSB was replaced by FSVB. Two passes of FSVB decreased the thickness of the IMC layer, void volume percentage, and the formation of micro-cracks in the brazed sample.

Numerical Analysis of Single Edge Notched Tension Specimen With Fatigue Crack Parameter of Conventional Specimen Using Linear Elastic Fracture Mechanics

This paper describes the numerical analysis of planar crack growth in high strength steel API 5L X70 whose crack growth parameter is adopted from experimental compact tension (CT) specimen in previous literature. Apart from the fact that conventional fatigue crack growth specimen has bogus geometry constraints, the Single Edge Notched Tension (SENT) better replicate the crack-tip constraint conditions experienced in structures. Linear elastic fracture mechanics (LEFM) crack orientation is modelled with the finite element method in SENT model considering its geometry functions a/W ratio to determine its crack growth rate based on constant amplitude load. The virtual crack closure technique tool in MSC Marc/Mentat software with adaptive and global remeshing is applied to assess high cycle fatigue crack propagation using the SENT model. The crack growth pattern for the 3-dimensional simulation characteristics is similar with that of the CT Specimen experimental procedure. Furthermore, the results of the crack propagation and the cycle count demonstrated good agreement with bearable discrepancy with maximum percentage difference of about 14.1 % for the HAZ and 6.4% for the weld and parent metal compared to the experimental resultsfrom literature.

Mechanical Properties and Failure Mechanisms of Refill Friction Stir Spot Welds

Refill friction stir spot welding (RFSSW) is an innovative solid-state welding technology for aluminum structures. The presented study aimed to evaluate the mechanical properties of refill spot welds and their failure mechanisms with the use of industrial test standards. The mechanical properties of refill spot welds were compared with those of rivet joints with comparable joint sizes. Static load tests indicated that RFSSW coupons demonstrate higher ultimate shear strengths but slightly lower ultimate tension strengths than those of rivet coupons. Fatigue test results indicated that both RFSSW coupons and rivet coupons demonstrate comparable performances during low-load-level fatigue lap shear tests but RFSSW coupons outperform rivet coupons during high-load-level fatigue lap shear tests. The failure mechanisms of refill spot welds were characterized in terms of external loading, parent metal properties, and weld properties. Refill spot weld failures included parent metal tensile failures, nugget pullouts, and interfacial failures. A refill spot weld may demonstrate one or a combination of these mechanical failures. Although the mechanical tests of refill spot welds demonstrated promising results with predictable failure mechanisms, the metallurgical evolution involved in RFSSW remains a subject to study.

Tensile strength of welded joints in low carbon steel using metal inert gas (MIG) welding

The development of technology that has penetrated the industrial sector is very rapid. Many industrial fields apply the use of MIG (Metal Inert Gas) welding for various jobs in steel construction, especially mild carbon steel. MIG welding has good welding results and fast welding time efficiency. The purpose of this study is to analyze the tensile strength of welded joints on low carbon steel using MIG welding. The experimental method used in this study is to perform MIG welding on low-carbon steel plate profiles. The welded carbon steel is used as a test specimen and is formed according to the ASTM E8-M standard. Tensile testing is performed using a Shimadzu UH-300 kN type tensile testing machine. From this study, the tensile strength value of the test specimen welded by MIG (Metal Inert Gas) welding is higher than the tensile strength of the parent metal (low carbon steel), so this shows the strength of the weld joint. The average value of tensile strength on the test specimen is (σ) 507.40 N/mm2 and average strain (ɛ) 3.63%. The MIG welding process, between the base metal and filler metal with different chemical compositions, can cause mixing and a dilution effect of two compositions.

Combinatorial Screening of Anodic Memristors Based on Hafnium-tantalum Mixed Oxides

Among valve metals, Ta and Hf are the most studied high-κ dielectric materials for development of the next-generation non-volatile electronic components, commonly known as memristors. Redox-based resistive switching memories (ReRAMs) and artificial neural networks are applications examples of metal-insulator-metal memory types. An insulating layer, interposed between the bottom and the top conducting electrodes, is the determining factor in memristive performance. From this aspect, oxidized forms of Hf and Ta are promising candidates to be used as solid-state electrolytes, allowing conductive filaments formation (CFs) inside the oxide layer. There is a strongly motivated scientific interest for the implementation of anodic oxides in memristive devices due to its simple, cost-efficient and controllable fabrication. However, properties of anodic memristors based on Hf and Ta are not yet fully investigated and several parameters still have to be examined in detail. Herein, influence of the electrolyte selection on Hf and Ta anodic memristors was studied. Consequently, anodization parameters were optimized and applied for the fabrication of memristors based on Hf-Ta alloys spread across a thin film combinatorial library. Parent metals and their mixtures served as bottom electrodes and, identical to the case of Pt top electrode, they were deposited by sputtering. The total compositional spread of Hf-Ta library was ranging from 5 to 92 at.% Hf and was distributed across three Si wafers. The memristive properties of devices based on mixed anodic oxides were screened with a resolution of 1 at.%, thus offering a comparative investigation of a high number of compositionally different devices. Generally, the ratios between resistance states for Ta and Hf memristors were approximately in the same range, as well as their number of switching voltage levels. Nevertheless, in both cases memory and electrical characteristics were dictated by the incorporation of electrolyte species, which was confirmed by XPS. Therefore, for devices based on pure metals, the memristive behavior varied only as depending on the electrochemical conditions used for device fabrication. However, no electrolyte incorporation was observed in case of devices based on Hf-Ta library. Memristive properties could have been related only to different compositions which were grouped in three zones containing alloys showing similar behaviors. An improvement of resistance states ratios in some zones by orders of magnitude was achieved, as compared to ratios obtained for devices based on pure metals. Additionally, variations between the zones of unipolar and bipolar switching behavior were observed. HRTEM and hard X-ray XPS were done in order to compare the CFs within the mixed oxide layers for memristors from different zones. Clearly, the novelty of this work is the found spectra of different memristive properties for anodic Hf and Ta memristors and anodic memristors based on numerous Hf-Ta alloys. Such approach is offering the possibility of better understanding whether the switching mechanism is based on electrolyte species, oxygen vacancies, metallic species movement or formation of additional vacancies by redox reactions or thermal field for each specific composition or electrochemical parameters. Conclusively, this may be an important step towards defect engineered memristors fabrication, as intrinsically offered by the anodic process of memristive formation.

The butt of CP-Ti/304 stainless steel and CP-Ti/T2 bimetallic sheets using laser-induction heating welding technology

In this work, the CP-Ti/304 stainless steel (SS) and CP-Ti/T2 bimetallic sheets were implemented successfully using laser-induction heating welding technology without the Ti-Fe and Ti-Cu brittle intermetallics was formed in the joint. The CP-Ti of parent layer metal was welded by laser, the 304 SS and T2 of flyer layer metal were connected by induction heating welding. The induction heating welding have the advantages of only the BCuP-2 wire was melted with low heat input and the specimen of welding experiment was without heated. As the melt point of BCuP-2 wire was 710–800 °C, lower than the melt point of flyer layer metal 304 SS (1454 °C) and T2 (1083 °C) and the parent layer metal CP-Ti (1660 °C). When the process of induction heating welding, the parent and flyer layer metal was not melted and only the BCuP-2 wire was melted and filled the groove. Thus the dissimilar metals mixing was avoided completely, the Ti-Fe intermetallics without formed. The narrow transition layer was formed between the laser weld zone (WZ1) and the induction heating weld zone (WZ2) with the main structures of Cu, Cu3P and α-Ti. The joint was fractured at the WZ1 and the 304 SS side of WZ2 with a maximum tensile strength was ascertained to be 600 MPa.

EFFECT OF TOOL PIN PROFILES OVER SQUARE WAVE TOOL PATH PATTERN ON FRICTION STIR WELDING OF AA6061-CU DISSIMILAR ALLOYS

In this present work friction stir welding of Al6061-annealed pure copper dissimilar metals with square wave pattern tool pin movementwas investigated. The aim of this experiment is to identify the significance square wave tool movement on friction stir welding process along with three different tool pin profiles. Different tool pin profiles of square, round and hexaspiral shapes were selected and their significant outcomes were unveiled. Friction stir welding process parameters of 1500 and 2000rpm & tool pin movement step size of 1.0mm and 2.0mm & weaving rate of 100mm/min and 150mm/min were selected. The advantages of tool movement pattern and tool pin profile shape wereexamined by mechanical testing, microstructure analysis. The mechanical results were showed that process parameter of 1500 rpm, 1.0mm step size, weldingrate of 150mm/min and square tool pin profile combination gives better mechanical properties. Micro structural results unveiled achievement of better grain refinement and uniform dispersion of micro constituents by implementation of square wave tool pin movement pattern along with square tool pin profile.The EDAX report confirms that the weld nugget contains both aluminum and copper as equal percentage, which indicates fine mixing of two parent metals.

The Effect of Precipitation hardening Heat Treatment on Impact Toughness and Tensile Properties of AA6063 Aluminum Alloy Reinforced with Hybrid Particles from Al2O3 and Graphite

Aluminum based composite are getting a vast scope nowadays because of its high properties and availability as fit large industrial development. (AMC) Aluminum metal-matrix composites is new engineering materials which contains two or more materials with different properties one being a metal from Aluminum and other may be metal, ceramic , glass reinforced materials. So in This present article We try to prepare hybrid composite materials based on aluminum alloy (AA6063) and reinforcement it by shared particles having size of micron of Alumina (7.5 wt%) and Graphite particles are added in specific countrified parentage (2.5 , 5 , 7.5 , 10 wt%) by stir casting technique to obtain hybrid Aluminum Which having the improving mechanical properties ,Heat treatment (solution heat treatment-artificial aging) are carried out on all samples ,After that inspections and mechanical tests have be done on all reinforcement samples , The results of Scanning electron microscope have shown uniform distribution of hybrid reinforced particles in matrix alloy and hybrid reinforced Aluminum alloy successfully prepared using stir casting method. The results of tests have shown The Impact toughness, , and Ultimate tensile strength were determined, with the addition of reinforcement the properties and effect of Precipitation hardening Heat treatment are improved compared to the parent metal Aluminum (6063) alone.

EFFECT OF PRE-HEATING ON THE MECHANICAL PROPERTIES OF FRICTION STIR WELDING FOR 6061 ALUMINUM ALLOY

Friction stir welding (FSW) process is a solid-state joining invented via the Welding Institute in 1991 at a great rate emerging as an application by fusion welding for joining different alloys. The wrought aluminum alloy 6061 is heat treatable and possesses a high corrosion resistance. This alloy has been used in a wide range of applications, like arenas gymnasiums and trains bodies. Aluminum alloy 6061 cannot be easily welded by the conventional fusion welding process because of the cracks that make the mechanical of welding joint very weak. In FSW, many parameters effect on its welding process. In the present research, the pre-heating effect on the aluminum 6061 sheet at 100°C and 150°C was studied. This heat has to be given for obtaining a defect-free as well as quality joint. Result manifested that the welding without pre-heating the parent metal at a (1120 r.p.m) rotational speed and a (30 mm/min) welding speed gave the best result of the ultimate tensile strength (236 N/mm2).

Welding-induced yield strength heterogeneity in X100Q: Modelling and characterisation

Yield strength (YS) heterogeneity in X100Q high strength low alloy (HSLA) steel welded joints is a key factor which influences fatigue life performance. The effects of welding-induced microstructural changes are investigated using a mechanistic YS model, which enables understanding of the key strengthening mechanisms which give rise to YS heterogeneity in X100Q. The model is used to predict YS in parent metal, physically-simulated fine-grain heat-affected zone material, and inter-critical heat-affected zone material, incorporating cooling rate effects. The model successfully predicts the measured welding-induced YS heterogeneity, with high-angle boundary (HAB) and precipitate strengthening mechanisms as dominant factors.

Characterization of the cyclic softening and remaining creep behaviour of P92 steel weldment

Different micro-regions of weldment are expected to present various cyclic softening behaviours during creep–fatigue interaction (CFI), which has a significant influence on the remaining mechanical properties. The present work aims to investigate the cyclic softening and remaining creep behaviour of different micro-regions of P92 steel weldment using electron backscattered diffraction (EBSD) and nanoindentation technology. CFI tests were performed and interrupted at various pre-set fatigue cycles at elevated temperature of 650 °C and hold time of 180 s, and thereafter EBSD analyses, nanoindentation tests and high-temperature creep tests were conducted on these interrupted specimens. Experimental results reveal that the microstructure of the parent metal and fine austenite grain heat-affected zone, which is adjacent to the intercritical heat affected zone, are sensitive to CFI loading. Notably, the microstructural evolution in intercritical heat affected zone almost reaches saturated after fatigue cycles of 20%Nf. Nanoindentation results uncover that the intercritical heat affected zone exhibits the lowest elastic modulus and microhardness, and with increasing the number of fatigue cycles, the weakest region changes. Accordingly, creep fracture location transits and creep life was degraded. Finally, a fatigue damage parameter based on the microhardness was developed to capture the effects of CFI on remaining creep life.

Research on the performance of laser-MIG arc tandem welding of CP-Ti/304 stainless steel bimetallic sheets

In this study, CP-Ti/304 stainless steel (SS) bimetallic sheets were prepared without the formation of Ti-Fe intermetallics in the joint. This required preparing a groove in the flyer and parent layer, and melting S211 wire using laser-MIG arc welding in tandem. The laser was used for the parent layer metal (CP-Ti) and the MIG arc was used for melting the S211 wire and filling the flyer layer groove. As the melting points of the parent layer metal CP-Ti (1660 °C) and the flyer layer metal 304 SS (1454 °C) were higher than the fill wire S211 (965–1035 °C), the parent and flyer layer metals were joined without melting. Liquid mixing of dissimilar metals was avoided and Ti-Fe intermetallics were not formed. The joint was observed to fracture at the laser weld zone and the right side of MIG arc weld zone, with a maximum tensile strength of approximately 680 MPa.