Evaluation of High Cycle Fatigue Properties of Double Side Welded AISI 321 Plates Using GTAW Process for Pressure Vessels

2021 ◽  
Author(s):  
Mohan Kumar S ◽  
A. Rajesh Kannan ◽  
Pramod R. ◽  
Pravin Kumar N ◽  
Nallathambi Siva Shanmugam ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Fatigue Behavior ◽  
Fatigue Behaviour ◽  
Pressure Vessels ◽  
Fatigue Properties ◽  
Dendritic Microstructure ◽  
Gas Tungsten Arc ◽  
Gtaw Process ◽  
Fatigue Rupture ◽  
Aisi 321

Abstract Titanium stabilized AISI 321 material (UNS S32100) is generally preferred in the pressure vessel industry as they are not sensitive to intergranular corrosion. In critical applications, the fatigue behaviour of weld seams are amongst the most stringent requirements. The microstructural characteristics and fatigue performance of double side welded AISI 321 plate having 6 mm thickness were evaluated in this work. AISI 321 was welded with Double side-gas tungsten arc welding (DS-GTAW) process. The fatigue behavior was examined under a loading ratio of 0.1 for two different specimens: Base metal (BM) and Weld metal (WM). Monotonic tensile results show the improved tensile properties of WM compared to BM samples. The fatigue strength of WM (332.6 MPa) was 25% higher than that of BM (265.7 MPa) specimen and is attributed to the increase in ferrite volume along with dendritic microstructure. The change in the fraction of low angle grain boundaries (LABs) and high angle grain boundaries (HABs) improved the tensile and fatigue properties. The stress amplitudes influenced the degree of striations in the BM and WM. Final fracture surfaces were characterized with dimples and micro-voids, revealing the ductile mode of fatigue fracture. The fatigue rupture surfaces of BM and WM samples at different stress regimes are discussed.

Fatigue Behaviour of Ti-6Al-4V Alloy in Vacuum and at Low Temperature

2008 ◽  
Vol 41-42 ◽  
pp. 83-90 ◽  
Author(s):  
J.H. Zuo ◽  
Z.G. Wang ◽  
En Hou Han
Keyword(s):  
Low Temperature ◽  
Fatigue Fracture ◽  
Room Temperature ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Sample Surface ◽  
Fatigue Behaviour ◽  
Fatigue Properties ◽  
Fatigue Fracture Surface ◽  
Cracks Propagation

Investigations have been conducted on the fatigue behavior of Ti-6Al-4V alloy with the bimodal microstructure in air at room temperature, in vacuum at room temperature and in vacuum at low temperature (100K), respectively. The results show that the fatigue life of this alloy is longer in vacuum and/or at low temperature than that in air at room temperature. The combination of vacuum and low temperature can much improve the fatigue properties of this alloy because of their purifying effect on fatigue cracks propagation. SEM observation of fatigue fracture surface indicates that all the fatigue cracks initiate in the sample surface when Nf ≦106 cycles. The above three testing conditions lead to different modes of fatigue crack propagation and therefore much different morphology of fatigue fracture.

Comparison Between EBW and GTAW for Turmo IV C Compressor Blade Repairs

1995 ◽  
Vol 117 (3) ◽  
pp. 545-553
Author(s):  
W. Miglietti
Keyword(s):  
Electron Beam Welding ◽  
Weld Zone ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Parent Metal ◽  
Compressor Blades ◽  
Metallographic Examination ◽  
Gas Tungsten Arc ◽  
Gtaw Process ◽  
Stringent Test

A research study was undertaken to evaluate whether electron beam welding (EBW) or gas tungsten arc welding (GTAW) could be utilized for repairs to the leading edges of the Turmo IV C compressor blades. These blades are manufactured from Ti-6Al-4V. The study entailed performing a series of welding trials. For the GTAW process a matching filler metal to the parent metal was used, whereas for the EBW process, the welds were made autogenously. After metallographic examination of the weld microstructure, mechanical property assessments were undertaken, namely tensile and fatigue tests, the latter being a stringent test to evaluate the performance of the welded joint. The results demonstrated that the EB welds had equivalent properties to the parent metal, whereas the GTA welds had poorer fatigue properties due to undesirable microstructure that resulted in the weld zone. The results achieved herein showed that the EBW process would be an appropriate technique for the restoration of these compressor blades.

scholarly journals Comparison Between EBW and GTAW for TURMO IV C Compressor Blade Repairs

1994 ◽  
Author(s):  
W. Miglietti
Keyword(s):  
Electron Beam Welding ◽  
Weld Zone ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Parent Metal ◽  
Compressor Blades ◽  
Metallographic Examination ◽  
Gas Tungsten Arc ◽  
Gtaw Process ◽  
Stringent Test

A research study was undertaken to evaluate whether electron beam welding (EBW) or gas tungsten arc welding (GTAW) could be utilised for repairs to the leading edges of the Turmo IV C compressor blades. These blades are manufactured from Ti-6Al-4V. The study entailed performing a series of welding trials. For the GTAW process a matching filler metal to the parent metal was used whereas for the EBW process, the welds were made autogenously. After metallographic examination of the weld microstructure, mechanical property assessments were undertaken, namely tensile and fatigue tests, the latter being a stringent test to evaluate the performance of the welded joint. The results demonstrated that the EB welds had equivalent properties to the parent metal whereas the GTA welds had poorer fatigue properties due to undesirable microstructure that resulted in the weld zone. The results achieved herein showed that the EBW process would be an appropriate technique for the restoration of these compressor blades.

scholarly journals From the fatigue properties of Ti6Al4V produced by ALM selective laser melting process to the mechanical design of an aeronautical part

2020 ◽  
Vol 321 ◽  
pp. 03032
Author(s):  
François Edy ◽  
Viet-Duc LE ◽  
Claudia BIERE ◽  
Monica Perez ◽  
Etienne Pessard ◽  
...  
Keyword(s):  
Selective Laser Melting ◽  
Mechanical Design ◽  
Fatigue Behavior ◽  
Melting Process ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Laser Melting ◽  
Fatigue Design ◽  
Process Strategy

Selective laser melting SLM is investigated through a study of redesign and characterization of an aeronautic part made of titanium Ti6Al4V. The part must ensure an excellent static and fatigue behaviour. The methodology developed hereby follows 3 main steps: First, the influence of laser power, laser speed and hatch distance on the amount/rate of porosity is performed to define optimized process parameters. Then, the influence of building process strategy, i.e. building direction or as-built surface roughness on the static and fatigue behaviour are studied and understood by following a vast experimental campaign. Obtained properties are finally used in a topology optimization study to find the best compromise between part weight and fatigue behavior . 3 prototypes of simulated part are produced and then characterized. Fatigue tests are conducted on the component and confirm the fatigue design proposed. Obtained results are encouraging and illustrate the fatigue design optimization of a complex Additive Manufacturing component.

scholarly journals Arc Characteristics and Weld Bead Microstructure of Ti-6Al-4V Titanium Alloy in Ultra-high Frequency Pulse Gas Tungsten Arc Welding (UHFP-GTAW) Process

2020 ◽  
Vol 26 (4) ◽  
pp. 426-431
Author(s):  
Wei LI ◽  
Gaochong LV ◽  
Qiang WANG ◽  
Songtao HUANG
Keyword(s):  
Titanium Alloy ◽  
Fusion Zone ◽  
Arc Welding ◽  
Gas Tungsten Arc Welding ◽  
Weld Bead ◽  
Gas Tungsten Arc ◽  
Arc Characteristics ◽  
Arc Pressure ◽  
Gtaw Process ◽  
Gas Tungsten

To resolve the problem of grain coarsening occurring in the fusion zone and the heat-affected zone during conventional gas tungsten arc welding(C-GTAW) welded titanium alloy, which severely restricts the improvement of weld mechanical properties, welding experiments on Ti-6Al-4V titanium alloy by adopting ultra-high frequency pulse gas tungsten arc welding (UHFP-GTAW) technique were carried out to study arc characteristics and weld bead microstructure. Combined with image processing technique, arc shapes during welding process were observed by high-speed camera. Meanwhile the average arc pressure under various welding parameters were obtained by adopting pressure measuring equipment with high-precision. In addition, the metallographic samples of the weld cross section were prepared for observing weld bead geometry and microstructure of the fusion zone. The experimental results show that, compared with C-GTAW, UHFP-GTAW process provides larger arc energy density and higher proportion of arc core region to the whole arc area. Moreover, UHFP-GTAW process has the obviously effect on grain refinement, which can decrease the grain size of the fusion zone. The results also revealed that a significant increase of arc pressure while increasing pulse frequency of UHFP-GTAW, which could improve the depth-to-width ratio of weld beads.

scholarly journals Quantitative Analysis of Inclusion Engineering on the Fatigue Property Improvement of Bearing Steel

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 476 ◽  
Author(s):  
Chao Gu ◽  
Min Wang ◽  
Yanping Bao ◽  
Fuming Wang ◽  
Junhe Lian
Keyword(s):  
Fatigue Life ◽  
Quantitative Analysis ◽  
Critical Size ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Fatigue Property ◽  
Bearing Steel ◽  
Fatigue Properties ◽  
Bearing Steels ◽  
Inclusion Distribution

The fatigue property is significantly affected by the inner inclusions in steel. Due to the inhomogeneity of inclusion distribution in the micro-scale, it is not straightforward to quantify the effect of inclusions on fatigue behavior. Various investigations have been performed to correlate the inclusion characteristics, such as inclusion fraction, size, and composition, with fatigue life. However, these studies are generally based on vast types of steels and even for a similar steel grade, the alloy concept and microstructure information can still be of non-negligible difference. For a quantitative analysis of the fatigue life improvement with respect to the inclusion engineering, a systematic and carefully designed study is still needed to explore the engineering dimensions of inclusions. Therefore, in this study, three types of bearing steels with inclusions of the same types, but different sizes and amounts, were produced with 50 kg hot state experiments. The following forging and heat treatment procedures were kept consistent to ensure that the only controlled variable is inclusion. The fatigue properties were compared and the inclusions that triggered the fatigue cracks were analyzed to deduce the critical sizes of inclusions in terms of fatigue failure. The results show that the critical sizes of different inclusion types vary in bearing steels. The critical size of the spinel is 8.5 μm and the critical size of the calcium aluminate is 13.5 μm under the fatigue stress of 1200 MPa. In addition, with the increase of the cleanliness of bearing steels, the improvement of fatigue properties will reach saturation. Under this condition, further increasing of the cleanliness of the bearing steel will not contribute to the improvement of fatigue property for the investigated alloy and process design.

Mechanical Properties of Equal-Channel Angular Extrusion-Processed Al-20Zn Alloy

2012 ◽  
Vol 445 ◽  
pp. 195-200
Author(s):  
Murat Aydin ◽  
Yakup Heyal
Keyword(s):  
Mechanical Properties ◽  
Impact Toughness ◽  
Equal Channel Angular Extrusion ◽  
Considerable Change ◽  
Fatigue Properties ◽  
Dendritic Microstructure ◽  
Two Phase ◽  
Angular Extrusion ◽  
Alloy Increase ◽  
The Impact

The mechanical properties mainly tensile properties, impact toughness and high-cycle fatigue properties, of two-phase Al-20Zn alloy subjected to severe plastic deformation (SPD) via equal-channel angular extrusion (ECAE) using route A up to 2 passes were studied. The ECAE almost completely eliminated as-cast dendritic microstructure including casting defects such as micro porosities. A refined microstructure consisting of elongated micro constituents, α and α+η eutectic phases, formed after ECAE via route A. As a result of this microstructural change, mechanical properties mainly the impact toughness and fatigue performance of the as-cast Al-20Zn alloy increased significantly through the ECAE. The rates of increase in fatigue endurance limit are approximately 74 % after one pass and 89 % after two passes while the increase in impact toughness is 122 %. Also the yield and tensile strengths of the alloy increase with ECAE. However, no considerable change occurred in hardness and percentage elongation of the alloy. It was also observed that the ECAE changed the nature of the fatigue fracture characteristics of the as-cast Al-20Zn alloy.

Fatigue Behaviour of Friction Stir Welded Steel Joints

2014 ◽  
Vol 891-892 ◽  
pp. 1488-1493 ◽  
Author(s):  
José Azevedo ◽  
Virgínia Infante ◽  
Luisa Quintino ◽  
Jorge dos Santos
Keyword(s):  
Base Material ◽  
Welding Process ◽  
Steel Structures ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Welded Steel ◽  
Shipbuilding Industry ◽  
Friction Stir ◽  
Steel Joints

The development and application of friction stir welding (FSW) technology in steel structures in the shipbuilding industry provide an effective tool of achieving superior joint integrity especially where reliability and damage tolerance are of major concerns. Since the shipbuilding components are inevitably subjected to dynamic or cyclic stresses in services, the fatigue properties of the friction stir welded joints must be properly evaluated to ensure the safety and longevity. This research intends to fulfill a clear knowledge gap that exists nowadays and, as such, it is dedicated to the study of welded steel shipbuilding joints in GL-A36 steel, with 4 mm thick. The fatigue resistance of base material and four plates in as-welded condition (using several different parameters, tools and pre-welding conditions) were investigated. The joints culminate globally with defect-free welds, from which tensile, microhardness, and fatigue analyses were performed. The fatigue tests were carried out with a constant amplitude loading, a stress ratio of R=0.1 and frequency between 100 and 120 Hz. The experimental results show the quality of the welding process applied to steel GL-A36 which is reflected in the mechanical properties of joints tested.

The Fatigue Behaviour of a High Strength CrNi-Steel Regarding Fretting Fatigue

2012 ◽  
Author(s):  
Thomas Christiner ◽  
Johannes Reiser ◽  
István Gódor ◽  
Wilfried Eichlseder ◽  
Franz Trieb ◽  
...  
Keyword(s):  
High Strength ◽  
Contact Problems ◽  
Fatigue Behaviour ◽  
Fretting Fatigue ◽  
Service Performance ◽  
Fatigue Properties ◽  
Material Behaviour ◽  
Reliable Prediction ◽  
Damage And Failure ◽  
Lubrication Conditions

In many assemblies of moving components, contact problems under various lubrication conditions are lifetime-limiting. There, relative motion of contacting bodies, combined with high loads transmitted via the contact surface lead to fretting fatigue failure. For a reliable prediction of in service performance load type, different damage and failure mechanisms that may be activated during operation have to be known. In this contribution selected results of a currently conducted research project are presented. The aim of this study was to examine the material behaviour of a surface stressed steel. The influence of the fretting regime on fatigue properties has been investigated.

Very High Cycle Fatigue Behavior and Life Prediction of a Low Strength Weld Metal at Moderate Temperature

2011 ◽  
Author(s):  
Ming-Liang Zhu ◽  
Fu-Zhen Xuan ◽  
Zhengdong Wang
Keyword(s):  
Crack Initiation ◽  
Weld Metal ◽  
Room Temperature ◽  
Fatigue Behavior ◽  
Fatigue Properties ◽  
Dissimilar Welding ◽  
Initiation Mechanism ◽  
Metallic Inclusions ◽  
Low Strength ◽  
Very High

The fatigue properties of a low strength weld metal in a dissimilar welding joint in high cycle and very high cycle regimes were investigated by fully reversed axial tests in air at room temperature and 370°C. A clear duplex S-N curve existed as a result of the transition of fatigue failure mode from surface-induced failure to internal-induced failure at 370°C, while the S-N curve was continuously decreased at room temperature. A new model was successfully proposed to predict fatigue life, and interpret the crack initiation modes transition from surface inclusion to interior inclusion. It was concluded that cracks were initiated by competition among non-metallic inclusions, welding pores and discontinuous microstructures in high cycle regime. While in the very high cycle regime, non-metallic inclusions were the dominant crack initiation mechanism which depended on stress level, inclusion size as well as inclusion depth.

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