Material Property Determination of Vibration Fatigued DMLS and Cold-Rolled Nickel Alloys

Author(s):  
Onome Scott-Emuakpor ◽  
Tommy George ◽  
Joseph Beck ◽  
Jeremy Schwartz ◽  
Casey Holycross ◽  
...  

An experimental procedure for qualifying material properties from cyclically worked parts was investigated in support of aging gas turbine engines and digital twin initiatives. For aging components, remanufacturing or repair efforts are necessary to sustain the life cycles of engines; and for digital twin, the virtual representation of a part requires accurate geometric and component material property measurement. Therefore, having an effective, non-destructive way to assess the material performance of parts is necessary. Since low cycle, low strain, mechanical testing is the ideal experimental approach for non-destructively assessing material properties, investigating the accuracy and trends of tensile properties of fatigue loaded parts was important. The fatigued parts used for this study were specimens tested according to the George Fatigue Method, and the materials observed were cold-rolled Inconel Alloys 625 and 718, and direct metal laser sintering (DMLS) Nickel Alloy 718. The tensile material properties were compared against pristine (non-fatigued) and published data. The comparison for the cold-rolled 625 and 718 results show an increase and a decrease, depending on rolling direction, of tensile strength due to the effects of fatigue cycles; however, the variation of the vibration affected tensile properties are all within one standard deviation of the pristine data. The comparisons of DMLS Nickel Alloys was conducted against two sets of alloys from different suppliers, and the results showed that the tensile properties are sensitive to DMLS manufacturing parameters and post-sintering processes. A digital twin related, nondestructive, material property determination technique is also discussed in this manuscript. The true alloy density was determined with the water displacement method, and elastic modulus is determined with an iterative Ritz method model. The modulus is under-predicted with this method, but suggestions for improving the model are discussed.

Author(s):  
Dan Jia ◽  
Yong-Yi Wang ◽  
Steve Rapp

Abstract Vintage pipelines, which in the context of this paper refer to pipelines built before approximately 1970, account for a large portion of the energy pipeline systems in North America. Integrity assessment of these pipelines can sometimes present challenges due to incomplete records and lack of material property data. When material properties for the welds of interest are not available, conservative estimates based on past experience are typically used for the unknown material property values. Such estimates can be overly conservative, potentially leading to unnecessary remedial actions. This paper is a summary of PRCI-funded work aimed at characterizing material properties and flaw characteristics of vintage girth welds. The data obtained in this work can be utilized to understand and predict the behavior of vintage pipelines, which is covered in a companion paper [1]. The material property data generated in this work include (i) pipe base metal tensile properties in both the hoop (transverse) and the longitudinal (axial) directions, (ii) deposited weld metal tensile properties, (iii) macrohardness traverses, (iv) microhardness maps, and (v) Charpy impact transition curves of specimens with notches in the heat-affected zone (HAZ) and weld centerline (WCL). These data provide essential information for tensile strength, strength mismatch, and impact toughness. In addition to the basic material property data, instrumented cross-weld tensile (ICWT) tests were conducted on CWT specimens with no flaws, natural flaws, and artificially machined planar flaws. The ICWT tests provide an indication of the welds’ stress and strain capacity without and with flaws. For welds with even-matching or over-matching weld strengths, the CWT specimens usually failed outside of the weld region, even for specimens with natural flaws reported by non-destructive examination. Having over-matching weld strength can compensate for the negative impact of weld flaws. All tested girth welds were inspected using radiography and/or phased array ultrasonic testing. The inspection results are compared with the flaws exposed through destructive testing. The ability of these inspection methods to detect and size flaws in vintage girth welds is evaluated.


Alloy Digest ◽  
2003 ◽  
Vol 52 (4) ◽  

Abstract Metrode 20.70 Nb is a nickel-base consumable with a nominal composition of Ni, 20% Cr, and 2.5% Nb. This alloy is used to join a variety of oxidation-resistant nickel alloys. The product is a solid wire for tungsten inert gas (TIG), metal inert gas (MIG), and submerged arc welding (SAW). This datasheet provides information on tensile properties as well as fracture toughness. It also includes information on joining. Filing Code: Ni-606. Producer or source: Metrode Products Ltd.


Alloy Digest ◽  
2018 ◽  
Vol 67 (8) ◽  

Abstract Strenx 700 CR is a cold-rolled structural steel with a minimum yield strength of 700 MPa (102 ksi) used to produce stronger and lighter structures. Strenx 700 CR has good cold forming, welding, and cutting performance. This datasheet provides information on composition, physical properties, and tensile properties. It also includes information on surface qualities as well as joining. Filing Code: SA-819. Producer or source: SSAB Swedish Steel Inc..


Alloy Digest ◽  
2006 ◽  
Vol 55 (2) ◽  

Abstract Sandvik 12C27 is a martensitic stainless steel for knife applications. It is supplied in both the annealed or cold-rolled condition. This datasheet provides information on composition, microstructure, hardness, and tensile properties. It also includes information on forming and heat treating. Filing Code: SS-954. Producer or source: Sandvik Steel Company.


Alloy Digest ◽  
2019 ◽  
Vol 68 (12) ◽  

Abstract Strenx 1100 CR is a cold-rolled structural steel with a minimum yield strength of 1100 MPa (160 ksi) for stronger and lighter structures. This material is available as cut-to-length sheets. This datasheet provides information on composition, physical properties, and tensile properties. Filing Code: SA-859. Producer or source: SSAB Swedish Steel, Inc..


Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 476
Author(s):  
Sayed Amer ◽  
Ruslan Barkov ◽  
Andrey Pozdniakov

Microstructure of Al-Cu-Yb and Al-Cu-Gd alloys at casting, hot-rolled -cold-rolled and annealed state were observed; the effect of annealing on the microstructure was studied, as were the mechanical properties and forming properties of the alloys, and the mechanism of action was explored. Analysis of the solidification process showed that the primary Al solidification is followed by the eutectic reaction. The second Al8Cu4Yb and Al8Cu4Gd phases play an important role as recrystallization inhibitor. The Al3Yb or (Al, Cu)17Yb2 phase inclusions are present in the Al-Cu-Yb alloy at the boundary between the eutectic and aluminum dendrites. The recrystallization starting temperature of the alloys is in the range of 250–350 °C after rolling with previous quenching at 590 and 605 °C for Al-Cu-Yb and Al-Cu-Gd, respectively. The hardness and tensile properties of Al-Cu-Yb and Al-Cu-Gd as-rolled alloys are reduced by increasing the annealing temperature and time. The as-rolled alloys have high mechanical properties: YS = 303 MPa, UTS = 327 MPa and El. = 3.2% for Al-Cu-Yb alloy, while YS = 290 MPa, UTS = 315 MPa and El. = 2.1% for Al-Cu-Gd alloy.


Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2163
Author(s):  
Krzysztof Żaba ◽  
Tomasz Trzepieciński ◽  
Sandra Puchlerska ◽  
Piotr Noga ◽  
Maciej Balcerzak

The paper is devoted to highlighting the potential application of the quantitative imaging technique through results associated with work hardening, strain rate and heat generated during elastic and plastic deformation. The aim of the research presented in this article is to determine the relationship between deformation in the uniaxial tensile test of samples made of 1-mm-thick nickel-based superalloys and their change in temperature during deformation. The relationship between yield stress and the Taylor–Quinney coefficient and their change with the strain rate were determined. The research material was 1-mm-thick sheets of three grades of Inconel alloys: 625 HX and 718. The Aramis (GOM GmbH, a company of the ZEISS Group) measurement system and high-sensitivity infrared thermal imaging camera were used for the tests. The uniaxial tensile tests were carried out at three different strain rates. A clear tendency to increase the sample temperature with an increase in the strain rate was observed. This conclusion applies to all materials and directions of sample cutting investigated with respect to the sheet-rolling direction. An almost linear correlation was found between the percent strain and the value of the maximum surface temperature of the specimens. The method used is helpful in assessing the extent of homogeneity of the strain and the material effort during its deformation based on the measurement of the surface temperature.


Author(s):  
Sean M. Finley ◽  
J. Harley Astin ◽  
Evan Joyce ◽  
Andrew T. Dailey ◽  
Douglas L. Brockmeyer ◽  
...  

OBJECTIVE The underlying biomechanical differences between the pediatric and adult cervical spine are incompletely understood. Computational spine modeling can address that knowledge gap. Using a computational method known as finite element modeling, the authors describe the creation and evaluation of a complete pediatric cervical spine model. METHODS Using a thin-slice CT scan of the cervical spine from a 5-year-old boy, a 3D model was created for finite element analysis. The material properties and boundary and loading conditions were created and model analysis performed using open-source software. Because the precise material properties of the pediatric cervical spine are not known, a published parametric approach of scaling adult properties by 50%, 25%, and 10% was used. Each scaled finite element model (FEM) underwent two types of simulations for pediatric cadaver testing (axial tension and cardinal ranges of motion [ROMs]) to assess axial stiffness, ROM, and facet joint force (FJF). The authors evaluated the axial stiffness and flexion-extension ROM predicted by the model using previously published experimental measurements obtained from pediatric cadaveric tissues. RESULTS In the axial tension simulation, the model with 50% adult ligamentous and annulus material properties predicted an axial stiffness of 49 N/mm, which corresponded with previously published data from similarly aged cadavers (46.1 ± 9.6 N/mm). In the flexion-extension simulation, the same 50% model predicted an ROM that was within the range of the similarly aged cohort of cadavers. The subaxial FJFs predicted by the model in extension, lateral bending, and axial rotation were in the range of 1–4 N and, as expected, tended to increase as the ligament and disc material properties decreased. CONCLUSIONS A pediatric cervical spine FEM was created that accurately predicts axial tension and flexion-extension ROM when ligamentous and annulus material properties are reduced to 50% of published adult properties. This model shows promise for use in surgical simulation procedures and as a normal comparison for disease-specific FEMs.


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