On the Microstructures and Fatigue Behaviors of 316L Stainless Steel Metal Injection Molded with Gas- and Water-Atomized Powders

316L stainless steel samples are fabricated by metal injection molding using water-atomized and gas-atomized powder with different oxygen contents. The influences of oxygen on the microstructural evolution and fatigue properties of the samples are investigated. The oxygen tends to react with Mn and Si to form oxide particles during sintering. The oxides hamper the densification process and result in decreased sintered density. Moreover, their existence reduces the Mn and Si dissolving into the base metal and compromises the solution strengthening effect. The oxides lead to stress concentration in the tensile and fatigue tests and become the initiation sites of fatigue cracks. After sintering, the samples made from the gas-atomized powder have a much lower oxygen content compared to those made from the water-atomized powder, therefore, exhibiting much better mechanical properties. The tensile strength, yield strength and the elongation of the samples made from the gas-atomized powder are 560 MPa, 205 MPa, and 58%, respectively. Their fatigue lives are about one order of magnitude longer than the samples made from water-atomized powder, and also longer than those fabricated by powder metallurgy and selective laser sintering which were reported in other studies.

Download Full-text

Influence of Twins on Short Fatigue Cracks in Type 316L Stainless Steel

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.465.507 ◽

2011 ◽

Vol 465 ◽

pp. 507-510 ◽

Cited By ~ 4

Author(s):

S. Al Shahrani ◽

T. James Marrow

Keyword(s):

Stainless Steel ◽

316L Stainless Steel ◽

Fatigue Cracks ◽

Fatigue Tests ◽

Staircase Method ◽

Deformation Twins ◽

Type 316L ◽

316L Austenitic Stainless Steel ◽

Rotating Bending ◽

Type 316L Stainless Steel

The nature of arrested cracks in run-out fatigue tests of a type 316L austenitic stainless steel with electropolished surfaces has been investigated. The fatigue limit was determined in rotating-bending by means of the staircase method to be 302 ± 5 MPa. Arrested crack nuclei were shown to arrest at coherent deformation twins, developed by fatigue.

Download Full-text

Fatigue Properties of 316L Stainless Steel

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.204-208.3786 ◽

2012 ◽

Vol 204-208 ◽

pp. 3786-3789

Author(s):

Xiao Zhao

Keyword(s):

Stainless Steel ◽

Room Temperature ◽

316L Stainless Steel ◽

Low Cycle Fatigue ◽

Fatigue Cracks ◽

Testing Machine ◽

Experimental Studies ◽

Hydraulic Testing ◽

Fatigue Properties ◽

Cycle Fatigue

The present paper deals with experimental studies on the tension-tension fatigue properties of 316L stainless steel by using a servo-valve controlled electro-hydraulic testing machine at room temperature. The low cycle fatigue properties of 316L stainless steel were studied and the initiation mechanisms of fatigue cracks were investigated and analyzed with scanning electron microscopy (SEM). Preliminary results indicate that the S-N curve of 316L stainless steel descends linearly in the low cycle regime and fatigue failure initiates from inclusions/defects on the specimen surface.

Download Full-text

Low Cycle Tension-Tension Fatigue Properties of 316L Stainless Steel Thin Sheets

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.138-139.832 ◽

2011 ◽

Vol 138-139 ◽

pp. 832-835

Author(s):

Yong Jie Liu ◽

Qing Yuan Wang ◽

Ren Hui Tian ◽

Xiao Zhao

Keyword(s):

Stainless Steel ◽

Room Temperature ◽

316L Stainless Steel ◽

Fatigue Testing ◽

Fatigue Properties ◽

Loading Frequency ◽

Thin Sheets ◽

Effect Factor ◽

Mechanical Fatigue ◽

Tensile Fatigue

In this paper, tensile fatigue properties of 316L stainless steel thin sheets with a thickness of 0.1 mm are studied. The tests are implemented by using micro mechanical fatigue testing sysytem (MMT-250N) at room temperature under tension-tension cyclic loading. The S-N curve of the thin sheets descends continuously at low cycle region. Cyclic σ-N curve and ε-N curve are obtained according to the classical macroscopical fatigue theory. The results agree well with the experimental fatigue data, showing that the traditional fatigue research methods are also suitable for description of MEMS fatigue in a certain extent. The effect factor of frequency was considered in this study and the results show that the fatiuge life and the fatigue strength are increased as loading frequency increasing.

Download Full-text

Effects of Powder Characteristics on Selective Laser Melting of 316L Stainless Steel Powder

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.189-193.3664 ◽

2011 ◽

Vol 189-193 ◽

pp. 3664-3667 ◽

Cited By ~ 4

Author(s):

Sheng Zhang ◽

Qing Song Wei ◽

Guang Ke Lin ◽

Xiao Zhao ◽

Yu Sheng Shi

Keyword(s):

Stainless Steel ◽

Selective Laser Melting ◽

316L Stainless Steel ◽

Fine Powder ◽

Steel Powder ◽

Laser Melting ◽

Broad Size Distribution ◽

Lower Oxygen ◽

Powder Characteristics ◽

Loose Powder

316L stainless steel parts were manufactured via selective laser melting . This work stu- dies the effects of powder characteristics such as particle size and particle shape composition on the density. It shows that the powder with a broad size distribution and using spherical fine powder can lead to an increase in the density of the loose powder and thus the densification of the laser melted powder. The aerosol powder forms parts of lower oxygen content well, and the density can reach to 90%.

Download Full-text

The Characterization and Flow Behavior of 316L Stainless Steel Feedstock for Micro Metal Injection Molding (μMIM)

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.44-47.2872 ◽

2010 ◽

Vol 44-47 ◽

pp. 2872-2876

Author(s):

Pei Li Haw ◽

Norhamidi Muhamad ◽

Hadi Murthadha

Keyword(s):

Stainless Steel ◽

Injection Molding ◽

316L Stainless Steel ◽

Flow Behavior ◽

Palm Stearin ◽

Metal Injection Molding ◽

Injection Molding Process ◽

Binder System ◽

Molding Process ◽

Rheological Characterization

The rheological behaviors of the Micro Metal Injection Molding feedstock are important for the stability of the feedstock during micro injection molding process and quality of the final micro-components. Homogeneous feedstocks are preferable for MIM process to ensure the dimensional consistency of molded components and prevent the defects of powder-binder separation or particle segregation. In this work, feedstocks with various formulations of 316L stainless steel and binder system were prepared by using Brabender Plastograph EC Plus mixer. The binder system comprises of palm stearin, polyethelene (PE) and stearic acid. In order to obtain the viscosity, activation energy, flow behavior and mold ability index, the rheological characterization of the feedstocks were investigated in numerous conditions by using Shimadzu 500-D capillary rheometer The study showed that all of the 316L stainless steel feedstocks are homogenous with pseudo-plastic behaviors.

Download Full-text

The Influence of Laser Shock Peening on Fatigue Properties of AA2024-T3 Alloy with a Fastener Hole

Metals ◽

10.3390/met10040495 ◽

2020 ◽

Vol 10 (4) ◽

pp. 495

Author(s):

Ruslan Sikhamov ◽

Fedor Fomin ◽

Benjamin Klusemann ◽

Nikolai Kashaev

Keyword(s):

Fatigue Life ◽

Fatigue Cracks ◽

Initial Crack ◽

Fatigue Tests ◽

Laser Shock Peening ◽

Fatigue Properties ◽

Hole Drilling ◽

Laser Shock ◽

Fastener Hole ◽

Shock Peening

The objective of the present study was to estimate the influence of laser shock peening on the fatigue properties of AA2024-T3 specimens with a fastener hole and to investigate the possibility to heal the initial cracks in such specimens. Fatigue cracks of different lengths were introduced in the specimens with a fastener hole before applying laser shock peening. Deep compressive residual stresses, characterized by the hole drilling method, were generated into the specimens by applying laser shock peening on both sides. Subsequently, the specimens were subjected to fatigue tests. The results show that laser shock peening has a positive effect regarding the fatigue life improvement in the specimens with a fastener hole. In addition, laser shock peening leads to a healing effect on fatigue cracks. The efficiency of this effect depends on the initial crack length. The effect of laser shock peening on the fatigue life periods was determined by using resonant frequency graphs.

Download Full-text

Effect of Pre-Strain on Fatigue Properties of NHH Rail

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.261-263.1239 ◽

2004 ◽

Vol 261-263 ◽

pp. 1239-1244

Author(s):

Wen Xian Sun ◽

S. Nishida ◽

Nobusuke Hattori ◽

X.L. Yue

Keyword(s):

Fatigue Crack ◽

Fatigue Strength ◽

Fatigue Test ◽

Fatigue Cracks ◽

Fatigue Tests ◽

Fatigue Properties ◽

Slip Lines ◽

Propagation Behavior ◽

Strain Process ◽

Initiation And Propagation

In the present study, fatigue tests have been performed to study the effect of pre-strain on fatigue properties of NHH (New Head-Hardened) rail. The objectives of this study were: (1) to observe the microscopic behavior of specimens during pre-strain process, (2) to research the influence of pre-strain on fatigue strength of NHH rail and (3) to investigate initiation and propagation behavior of the fatigue crack. The results showed that plastic pre-strain decreased the fatigue strength of NHH rail; fatigue limits had no obvious variation among the different pre-strain ratios. Fatigue cracks initiated in the microscopic cracking or slip lines that were originated in the pre-strain process and propagated from these sites in the later fatigue test.

Download Full-text

Investigations on Fatigue Properties of Die Cast Magnesium Alloy AZ91HP at Very High Cycles

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.353-358.235 ◽

2007 ◽

Vol 353-358 ◽

pp. 235-238

Author(s):

Tang Li ◽

Qing Yuan Wang ◽

Q.F. Dou ◽

Chong Wang ◽

M.R. Sriraman

Keyword(s):

Magnesium Alloy ◽

Fatigue Cracks ◽

Ambient Air ◽

Fatigue Tests ◽

Fatigue Properties ◽

Loading Frequency ◽

Die Cast ◽

Cast Magnesium Alloy ◽

Cast Magnesium ◽

Very High

Very high cycle fatigue (VHCF) properties of high-pressure die cast Magnesium alloy AZ91HP have been investigated. Ultrasonic fatigue tests up to 109 cycles were conducted at the loading frequency of 20 kHz, under R=-1 condition and in ambient air. The experimental results show that specimens fail even after 107 cycles although the scatter seems to be large probably due to the presence of materials defects. However, there seems to be a fatigue limit at about 109 cycles. The fractures contain typical brittle features, with the fatigue cracks seen to initiate from the porosity in the material, either from the surface or beneath.

Download Full-text

Environmental Effects on Fatigue Crack Initiation in 2.25 Cr-1 Mo Steel and 316L Stainless Steel

Journal of Engineering Materials and Technology ◽

10.1115/1.3226043 ◽

1988 ◽

Vol 110 (3) ◽

pp. 240-246

Author(s):

V. K. Mathews ◽

T. S. Gross

Keyword(s):

Stainless Steel ◽

Fatigue Crack ◽

Crack Initiation ◽

Room Temperature ◽

316L Stainless Steel ◽

Silicone Oil ◽

Fatigue Crack Initiation ◽

Type A ◽

Order Of Magnitude ◽

Number Of Cycles

Blunt notch fatigue crack initiation tests for Type A387 2.25 Cr-1 Mo steel and 316L stainless steel were performed in air at room temperature, in silicone oil at room temperature, in V-131B coal process solvent at 100°C, and in chlorine-modified V-131B coal process solvent at 100°C. For both steels the most damaging environment was room temperature air. The number of cycles to initiate a crack were almost identical in the coal process solvent and the silicone oil for the Type A-387 steel. These two environments resulted in the longest crack initiation lifetime for the Type A-387 steel. The crack initiation lifetime for the Type A-387 steel in the chlorine modified V-131 B coal process solvent was roughly a factor of five less than the lifetime in the silicone oil and the unmodified coal process solvent. The crack initiation lifetime for the Type A-387 steel in room temperature air was a factor of 30 less than the lifetime in the silicone oil or the unmodified coal process solvent. The improvement of the crack initiation lifetime for the Type A-387 steel in the unmodified coal process solvent and the silicone oil is attributed to protection of the material from embrittlement from room temperature air. The decrease in crack initiation lifetime in the chlorine modified coal process solvent indicates that chlorine can be an active embrittling agent in the coal process solvent. The crack initiation lifetime for 316L stainless steel was longest in the silicone oil. The lifetime decreased somewhat in the unmodified coal process solvent with a further decrease for the chlorine modified coal solvent. The crack initiation lifetime in air was an order of magnitude lower than the lifetime in the silicone oil. The silicone oil and the coal process solvent apparently protected the 316L stainless from the embrittlement in air. However, the coal process solvent is not entirely inert as in the case of Type A-387 steel. The chlorine is an active embrittling agent for the 316L stainless steel in the coal process solvent.

Download Full-text