scholarly journals Lifetime assessment of the process-dependent material properties of additive manufactured AlSi10Mg under low-cycle fatigue loading

2020 ◽  
Vol 326 ◽  
pp. 07003
Author(s):  
Carl Fischer ◽  
Christoph Schweizer
Keyword(s):  
Heat Treatment ◽  
Layer Thickness ◽  
Surface Quality ◽  
Low Cycle Fatigue ◽  
Deformation Behaviour ◽  
Defect Size ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Cast Material ◽  
Near Surface

Systematic low-cycle fatigue (LCF) experiments are carried out on additive manufactured AlSi10Mg specimens for several material conditions with varying layer thickness, heat treatment, building direction and surface quality. The deformation behaviour depends significantly on the heat treatment. It is outlined that the process control and heat treatment can produce fatigue properties comparable with the cast material, whereby an as-built specimen surface leads to a lifetime reduction in all cases. The experiments are accompanied with detailed metallo- and fractographic investigations. For all tested LCF specimens, the defect type and the failure origin defect size are characterized in terms of the √area parameter by using scanning electron microscopy. The failure of the specimen is mostly caused by lack of fusion surface or near-surface defects, whereby the defect size is determined by the SLM process parameters, such as building direction, surface quality and layer thickness. On the basis of the experimental data and the observed defects, a mechanism-based, deterministic lifetime model is developed and adapted to the specific damage mechanisms of the additive manufactured AlSi10Mg alloy.

scholarly journals Low Cycle Fatigue Characteristics of Oxygen-Free Copper for Electric Power Equipment

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4237
Author(s):  
Takuma Tanaka ◽  
Togo Sugioka ◽  
Tatsuya Kobayashi ◽  
Ikuo Shohji ◽  
Yuya Shimada ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Electric Power ◽  
Stress Amplitude ◽  
Low Cycle Fatigue ◽  
Ebsd Analysis ◽  
Fatigue Properties ◽  
Power Equipment ◽  
Cycle Fatigue ◽  
Fracture Surfaces ◽  
Heat Treated

The effect of heat treatment on tensile and low cycle fatigue properties of the oxygen-free copper for electric power equipment was investigated. The heat treatment at 850 °C for 20 min, which corresponds to the vacuum brazing process, caused the grain growth and relaxation of strain by recrystallization, and thus, the residual stress in the oxygen-free copper was reduced. The tensile strength and 0.2% proof stress were decreased, and elongation was increased by the heat treatment accompanying recrystallization. The plastic strain in the heat-treated specimen was increased compared with that in the untreated specimen under the same stress amplitude condition, and thus, the low cycle fatigue life of the oxygen-free copper was degraded by the heat treatment. Striation was observed in the crack initiation area of the fractured surface in the case of the stress amplitude less than 100 MPa regardless of the presence of the heat treatment. With an increase in the stress amplitude, the river pattern and the quasicleavage fracture were mainly observed in the fracture surfaces of the untreated specimens, and they were observed with striations in the fracture surfaces of the heat-treated ones. The result of the electron backscattered diffraction (EBSD) analysis showed that the grain reference orientation deviation (GROD) map was confirmed to be effective to investigate the fatigue damage degree in the grain by low cycle fatigue. In addition, the EBSD analysis revealed that the grains were deformed, and the GROD value reached approximately 28° in the fractured areas of heat-treated specimens after the low cycle fatigue test.

scholarly journals The Influence of Heat Treatment on Low Cycle Fatigue Properties of Selectively Laser Melted 316L Steel

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5737
Author(s):  
Janusz Kluczyński ◽  
Lucjan Śnieżek ◽  
Krzysztof Grzelak ◽  
Janusz Torzewski ◽  
Ireneusz Szachogłuchowicz ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Negative Influence ◽  
Material Behavior ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
316L Steel ◽  
Material Fracture ◽  
Precipitation Heat

The paper is a project continuation of the examination of the additive-manufactured 316L steel obtained using different process parameters and subjected to different types of heat treatment. This work contains a significant part of the research results connected with material analysis after low-cycle fatigue testing, including fatigue calculations for plastic metals based on the Morrow equation and fractures analysis. The main aim of this research was to point out the main differences in material fracture directly after the process and analyze how heat treatment affects material behavior during low-cycle fatigue testing. The mentioned tests were run under conditions of constant total strain amplitudes equal to 0.30%, 0.35%, 0.40%, 0.45%, and 0.50%. The conducted research showed different material behaviors after heat treatment (more similar to conventionally made material) and a negative influence of precipitation heat treatment of more porous additive manufactured materials during low-cycle fatigue testing.

scholarly journals Influence and Sensitivity of Temperature and Microstructure on the Fluctuation of Creep Properties in Ni-Base Superalloy

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4758
Author(s):  
Zhihao Yao ◽  
Biao Zhou ◽  
Kaijun Yao ◽  
Hongying Wang ◽  
Jianxin Dong ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Residual Strain ◽  
Solution Heat Treatment ◽  
Low Cycle Fatigue ◽  
Fatigue Properties ◽  
Solution Temperature ◽  
Temperature Sensitive ◽  
Cycle Fatigue ◽  
Aero Engines

In this work, the sensitivity zone of microstructure and temperature for precipitation-strengthened nickel-based superalloys, used for turbine applications in aero-engines, has been firstly established. Heat treatment experiments with different solution temperatures were carried out. The microstructure evolution and creep residual strain sensitivity, low cycle fatigue properties, and tensile properties are analyzed, and the essential reason for the fluctuation of the mechanical properties of nickel-based superalloys was revealed. The main results obtained are as follows: following subsolvus solution heat treatment with a temperature of 1020 °C, samples have a high primary γ′I phase content, which is beneficial to low creep residual strain. Above the supersolvus solution temperature of 1040 °C, the creep residual strain value and low cycle fatigue performance fluctuate significantly. The essential reason for the dramatic fluctuation of performance is the presence of γ′ phases in different sizes and quantities, especially following the solution heat treatment in the temperature-sensitive zone of the γ′I phase, which is likely to cause huge fluctuations in the microstructure of tertiary γ′III phases. A zone of particular sensitivity in terms of temperature and microstructure for the γ′I phase is proposed. The range of suitable solution temperatures are discussed. In order to maintain stable mechanical properties without large fluctuations, the influence of the sensitivity within this temperature and microstructure zone on the γ′ phase should be considered.

Effect of heat treatment on low cycle fatigue properties of Cu–Cr–Zr alloy

2019 ◽  
Vol 158 ◽  
pp. 109940 ◽  
Author(s):  
Wang Junfeng ◽  
Chen Jinshui ◽  
Guo Chengjun ◽  
Zhang Jianbo ◽  
Xiao Xiangpeng ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Low Cycle Fatigue ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Zr Alloy

Effects of Modified Solution Heat Treatment on δ- Phase and Low Cycle Fatigue Properties of Inconel 718 Alloy

2006 ◽  
Vol 118 ◽  
pp. 71-76 ◽  
Author(s):  
Jae Keun Hong ◽  
Ji Hong Park ◽  
Nho Kwang Park ◽  
Seong Jun Kim ◽  
Chung Yun Kang
Keyword(s):  
Heat Treatment ◽  
Solution Heat Treatment ◽  
Room Temperature ◽  
Low Cycle Fatigue ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Alloy 718 ◽  
Cycle Fatigue ◽  
Standard Heat ◽  
Heat Treated

Effects of solution treatment on the microstructure and mechanical properties in wrought Alloy 718 were investigated. For the improvement of tensile and fatigue properties of wrought Alloy 718, a modified solution heat treatment(MSHT), heating at 1000 for 3 minutes followed by furnace cooling at the rate of 3/minute and holding at 985 for 8 minutes, was proposed. This treatment was performed repeatedly 3 times and the samples were subject to the standard aging treatment. For the purpose of comparison, a standard heat treatment(SHT) was also performed. The microstructures of modified solution heat treated specimens showed that small spherical shaped δ- phases were precipitated without grain growth, and the amount of δ-phases was smaller than that of standard heat treated specimens. However, the δ-phases of the standard heat-treated specimen showed needle-like morphologies. Tensile and low cycle fatigue tests were performed on both modified heat-treated and standard heat-treated specimens at room temperature, 350 and 650. Low cycle fatigue tests on the modified heat treated specimens showed promising results without reduction of strength. However, the tensile properties of modified solution treated specimens was almost the same as those of standard heat treated materials both at room temperature and 650.

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