Mechanical Characterization and Modeling of Direct Metal Laser Sintered Stainless Steel GP1

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Sanna F. Siddiqui ◽  
Abiodun A. Fasoro ◽  
Calvin Cole ◽  
Ali P. Gordon
Keyword(s):  
Stainless Steel ◽  
Mechanical Performance ◽  
Low Cycle Fatigue ◽  
Constitutive Models ◽  
Fatigue Tests ◽  
Material Behavior ◽  
Layer By Layer ◽  
Cycle Fatigue ◽  
Layer Deposition ◽  
Experimental Findings

The additive manufacturing (AM) process is unique in that it can facilitate anisotropy because of the layer-by-layer deposition technique intrinsic to this process. In order to develop a component for a desired application, it is necessary to understand the mechanics that facilitate this material behavior. This study investigates how build orientation affects the mechanical performance of as-built direct metal laser sintered (DMLS) stainless steel (SS) GP1 (also referred to as 17-4PH) through strain-controlled monotonic tension and completely reversed low-cycle fatigue (LCF) testing. The anisotropic behavior of DMLS SS GP1 is assessed for samples built along the horizontal plane. Fracture surfaces were found to exhibit ductile responses that were consistent with the σ–ε curves. Constitutive models (i.e., Ramberg–Osgood, Hahn) based upon linear elasticity and nonlinear plasticity are presented and used to simulate the monotonic discontinuous stress–strain yielding response of this material, which are found to be in agreement with the experimental data. A collection of low-cycle fatigue tests reveals initial strain hardening to stabilization, followed by softening to fracture. Tensile and fatigue material constants determined from experimental findings are also presented in this study. Plasticity effects on the life of varying build orientations are explored.

Modeling the Influence of Build Orientation on the Monotonic and Cyclic Response of Additively Manufactured Stainless Steel GP1/17-4PH

2017 ◽  
Author(s):  
Sanna F. Siddiqui ◽  
Nathan O’Nora ◽  
Abiodun A. Fasoro ◽  
Ali P. Gordon
Keyword(s):  
Stainless Steel ◽  
Mechanical Performance ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Constitutive Models ◽  
Material Behavior ◽  
Cycle Fatigue ◽  
Cyclic Response ◽  
Build Orientation ◽  
Experimental Findings

Rapid prototyping has led to strides in improved mechanical part design flexibility and manufacturing time. Along with these advances, however, is the extremely high costs associated with additively manufacturing components that can limit a comprehensive understanding of the mechanical performance of these materials. This can be circumvented through the use of constitutive models which can both support experimental findings in addition to providing approximations of expected material behavior. The present study has demonstrated the influence of build orientation on as-built direct metal laser sintered (DMLS) stainless steel (SS) GP1/17-4PH, manufactured along varying orientations in the xy build plane, through strain-controlled tension and completely reversed low cycle fatigue experiments. Experimental findings from monotonic tension testing are used to model failure surfaces, which can be used to approximate failure regions for DMLS SS GP1 manufactured along varying build orientations within the horizontal xy build plane. Further, a Chaboche model is used to simulate the cyclic response of this material based upon experimental findings through low cycle fatigue testing. Conclusive findings from these models are used to assess the vital role that build orientation plays in affecting the mechanical performance of additively manufactured materials.

Effect of Surface Finish and Loading Conditions on the Low Cycle Fatigue Life of Stainless Steel Welded Piping in PWR Environment

2013 ◽  
Author(s):  
Yuichi Fukuta ◽  
Yuichiro Nomura ◽  
Seiji Asada
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Austenitic Stainless Steel ◽  
Surface Finish ◽  
Loading Condition ◽  
Low Cycle Fatigue ◽  
Complex Loading ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Effect Of Surface

NUREG/CR-6909 of USA and JSME of Japan proposed new rules for evaluating environmental effects in fatigue analyses of reactors components. These rules were established from a lot of fatigue data with polished specimens under simple loading condition. The effects of surface finish or complex loading condition were reported in some papers, but these data were obtained with the simple shaped specimens. In order to evaluate the effects of surface finish and loading condition and to confirm the applicability of the proposed rules to actual components, Low Cycle Fatigue tests are performed in PWR environment with the specimens cut from 316 austenitic stainless steel welded piping. The pipes are machined to have three levels of surface finish condition and the load pattern simulating the thermal stress is applied to specimens. In this study, the effect of surface finish on fatigue life is included to be small for 316 austenitic stainless steel welded piping. Considering the insensitive region in the current evaluation rule, predicted accuracy is increased and possibility of improving the current rule is indicated.

Low-Cycle-Fatigue Properties of a 17-4 PH Stainless Steel Manufactured via Selective Laser Melting

2021 ◽  
Vol 877 ◽  
pp. 55-60
Author(s):  
Lorenzo Maccioni ◽  
Eleonora Rampazzo ◽  
Filippo Nalli ◽  
Yuri Borgianni ◽  
Franco Concli
Keyword(s):  
Stainless Steel ◽  
Selective Laser Melting ◽  
Low Cycle Fatigue ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Laser Melting ◽  
Softening Behavior ◽  
The One ◽  
Cylindrical Samples

In this paper, the static and low-cycle-fatigue (LCF) behavior of wrought samples of 17-4 PH stainless steel (SS) manufactured via Selective Laser Melting (SLM) are presented. On the one hand, several scholars have studied SLM materials and literature reports a huge amount of data as for the high-cycle-fatigue (HCF) behavior. On the other hand, few are the data available on the LCF behavior of those materials. The aim of the present research is to provide reliable data for an as-build 17-4 PH steel manufactured via SLM techniques. Only with quantitative data, indeed, it is possible to exploit all the advantages that this technology can offer. In this regard, both quasi-static (QS) and low-cycle-fatigue tests were performed on Additive Manufacturing (AM) cylindrical samples. Through QS tests, the constitutive low has been defined. Strain-controlled fatigue tests on an electromechanical machine were performed on 12 samples designed according to the ASTM standard. Tests were continued also after the stabilization was reached (needed for the cyclic curve described with the Ramberg-Osgood equation) to obtain also the fatigue (ε-N) curve. Results show that the material has a softening behavior. The Basquin-Coffin-Manson (BCM) parameters were tuned on the basis of the ε-N combinations after rupture.

Improvement of Thermomechanical Fatigue Life in Nitrogen Alloyed 316 Stainless Steel

2005 ◽  
Vol 475-479 ◽  
pp. 1429-1432 ◽  
Author(s):  
Dae Whan Kim ◽  
Chang Hee Han ◽  
Woo Seog Ryu
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Temperature Change ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Thermomechanical Fatigue ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Phase Condition ◽  
Higher Temperature

Fatigue tests of type 316 and 316LN stainless steel were conducted at RT and 600ı, 0.8~1.5% strain range for low cycle fatigue (LCF), 300~600ı, 0% strain range for thermal fatigue (TF) and 300~600ı, 2% strain range, in-phase or out-of-phase for thermomechanical fatigue (TMF). LCF, TF, and TMF lives were increased but saturation stresses were decreased with the addition of nitrogen. The higher temperature was the lower TF life at a same temperature change. The minimum temperature change for TF failure was more than 100ı. TMF life was higher at inphase condition than at out-of-phase condition. Fracture mode was transgranular for LCF and outof- phase of TMF and almost transgranular and small intergranular for TF and in-phase TMF.

Initial Aspects of Low-Cycle Fatigue Fracture of Martensitic Steels

2007 ◽  
Vol 348-349 ◽  
pp. 385-388 ◽  
Author(s):  
Tamaz Eterashvili ◽  
T. Dzigrashvili ◽  
M. Vardosanidze
Keyword(s):  
Plastic Deformation ◽  
Stainless Steel ◽  
Plastic Zone ◽  
Fatigue Fracture ◽  
Main Crack ◽  
Low Cycle Fatigue ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Slip Bands ◽  
Number Of Cycles

This study deals with the SEM and optical microscopic characterization of fatigue plastic deformation process during fatigue crack initiation to understand where, why and how cracks initiate under conditions of low cycle fatigue. Samples were prepared from the 13Х11Н2В2МФ high-chromium stainless steel used for fusion power applications. The low-cycle tests were conducted at room temperature with the standard V-notched samples prepared from conventional stainless steel. The following characteristics were studied during fatigue tests: 1 macrocrack propagation, 2. interaction between macrocrack and isolated microcracks, 3. interaction between macrocrack and slip bands, 4. interaction between macrocrack and microstructure elements of the steel. The above experiments show that during macrocrack propagation a plastic zone is formed around it, where isolated microcracks and slip bands of 2-3 different directions are observed. Measurement of plastic zone dimensions after different number of cycles of deformation show that plastic zone size increases during the first stage of cyclic deformation (until definite number of cycles are completed), and then remains unchanged. The observations show that main crack is composed of individual micro-components, the lengths of which are in a good correlation with the dimensions of microstructure elements of the steel (former austenite grains, martensite crystals). It was revealed that during growth, as a rule, macrocrack rarely propagates along isolated microcracks and slip bands. Direction of macrocrack propagation changes while passing from one microstructure element to another, so that main direction is the same. No preferable transcrystalline or intercrystalline propagation of macrocrack has been observed in the investigated steel. It is shown that after subsequent fatigue tests, dimensions of the previously created slip bands increase, and additional new slip band are also formed. The sites and frequency of slip bands’ formation in plastic zone are also studied. It was observed that the boundaries and mainly the sites of intersection of martensite crystals are the sites of isolated (rough) microcracks’ formation. The dimensions of slip bands are comparable with those of martensite crystals. The angles between the main crack propagation direction and slip bands varied from 30o to 60o, however, most of the slip bands were oriented at 45o to the main crack. Based on the obtained results a conclusion is made that plastic deformation in samples go inhomogeneously. In plastic zones, along with the heavily deformed areas, almost non-deformed areas are also observed. The speed of fatigue fracture increases with the increase in frequency and amplitude of deformations. Generally, the annealed samples are destructed prematurely in comparison with non-annealed ones of the investigated steel.

Influence of specimen diameter size on the deformation behavior and short-term strength range of an aluminum alloy

2020 ◽  
Vol 62 (4) ◽  
pp. 345-350
Author(s):  
Benjamin Seisenbacher ◽  
Richard Klösch ◽  
Gerhard Winter ◽  
Florian Grün
Keyword(s):  
Deformation Behavior ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Material Behavior ◽  
Cycle Fatigue ◽  
Mean Values ◽  
Strain Behavior ◽  
Specimen Diameter ◽  
Local Material

Abstract Components often manifest varied local behavior due to their manufacturing process. In order to be able to determine local material behavior in the best possible way, it is necessary to take specimens from the area under investigation. Due to constant developments in efficiency and lightweight construction, it is difficult to produce standard-compliant specimens from the examined area in a component. For this reason, specimens with smaller dimensions are often taken. Through the investigation of the influence of size in the area of high-cycle fatigue, it is well known that the size of a test specimen influences its lifespan. Not so much is known about the influence of specimen size on the behavior of material in the field of low-cycle fatigue (LCF). In this work, tensile, LCF and thermomechanical fatigue tests are performed using AlCu4PbMgMn with varied specimen geometries, the smallest test diameter being 3 mm, the largest 7.5 mm. The results of the tensile test show that the mean values of tensile strength for both diameters is within one percent. At LCF load and thermomechanical load, there are no or only slight deviations in deformation behavior. The low cycle fatigue behavior at RT is identical for both diameters. However, the results show that stress-strain behavior is the same for both test diameters, and fatigue behavior is the same, except in tests with high strain amplitudes and temperature.

Internal Crack Initiation in Low-Cycle Fatigue of Stainless Steel

2010 ◽  
Author(s):  
Masayuki Kamaya ◽  
Masahiro Kawakubo
Keyword(s):  
Stainless Steel ◽  
Crack Initiation ◽  
Strain Amplitude ◽  
Low Cycle Fatigue ◽  
Fatigue Tests ◽  
Internal Crack ◽  
Surface Cracks ◽  
Cycle Fatigue ◽  
Type Specimens ◽  
316 Stainless Steel

Internal cracks were observed on the fracture surface of Type 316 stainless steel specimens subjected to a low-cycle fatigue test, in which the strain amplitude was more than 1%. In some cases the specimens fractured due to these internal cracks. In this study, the reason and conditions for the internal crack initiation were examined. Fatigue experiments were conducted using Type 316 stainless steel. In order to enhance the internal crack initiation, the specimens were subjected to pre-damaging and surface cracks were removed before the start of the fatigue tests. It was shown that specimens fractured due to internal cracks when the strain amplitude of pre-damaging was more than 1% and hourglass-type specimens were used. The fatigue life was reduced largely due to the internal cracks and the magnitude of reduction was more significant for the smaller strain amplitude of the fatigue tests. Inclusions were observed at the origin of some internal cracks. It was deduced that the hourglass geometry of the specimen enhanced the internal crack initiation. Namely, the multi-axial field was one of the factors promoting the internal crack initiation.

scholarly journals Mechanical Performance versus Corrosion Damage Indicators for Corroded Steel Reinforcing Bars

2015 ◽  
Vol 2015 ◽  
pp. 1-19 ◽  
Author(s):  
Silvia Caprili ◽  
Jörg Moersch ◽  
Walter Salvatore
Keyword(s):  
Performance Indicators ◽  
Mechanical Performance ◽  
Low Cycle Fatigue ◽  
Corrosion Damage ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Reinforcing Bars ◽  
Steel Bar ◽  
Damage Indicators ◽  
Current Standards

The experimental results of a testing campaign including tensile and low-cycle fatigue tests on different reinforcing steel bar types in the as-delivered and corroded condition are presented. Experimental data were statistically analyzed adopting ANOVA technique; Performance Indicators (PIs), describing the mechanical performance characteristics of reinforcements, and Corrosion Damage Indicators (CDIs), describing the detrimental effects of corrosion phenomena, were determined and correlated in order to evaluate the influence of corrosion on the behaviour of reinforcing steels, providing useful information for designers in addition to what is presented in current standards.

scholarly journals An Energy-Based Unified Approach to Predict the Low-Cycle Fatigue Life of Type 316L Stainless Steel under Various Temperatures and Strain-Rates

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1090 ◽  
Author(s):  
Nae Tak ◽  
Jung-Seok Kim ◽  
Jae-Yong Lim
Keyword(s):  
Stainless Steel ◽  
Strain Rate ◽  
316L Stainless Steel ◽  
Low Cycle Fatigue ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Strain Rates ◽  
Cycle Fatigue ◽  
Type 316L ◽  
Type 316L Stainless Steel

An energy-based low-cycle fatigue model was proposed for applications at a range of temperatures. An existing model was extended to the integrated approach, incorporating the simultaneous effects of strain rate and temperature. A favored material at high temperature, type 316L stainless steel, was selected in this study and its material characteristics were investigated. Tensile tests and low-cycle fatigue tests were performed using several strain rates at a temperature ranging from room temperature to 650 °C. Material properties were obtained in terms of temperature using the displacement-controlled tensile tests and further material response were investigated using strain-controlled tensile tests. Consequently, no pronounced reduction in strengths occurred at temperatures between 300 and 550 °C, and a negative strain rate response was observed in the temperature range. Based on the low-cycle fatigue tests by varying strain rates and temperature, it was found that a normalized plastic strain energy density and a strain-rate modified cycle were successfully correlated. The accuracy of the model was discussed by comparing between predicted and experimental lives.

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