Influence of Microstructure and Defect Population on the Fatigue Performance of Cast A356-T6 Automotive Components

2014 ◽  
Vol 782 ◽  
pp. 301-305
Author(s):  
Radomila Konečná ◽  
Gianni Nicoletto ◽  
Enrica Riva
Keyword(s):  
Fatigue Strength ◽  
Cylinder Head ◽  
High Cycle Fatigue ◽  
Fatigue Testing ◽  
High Strength ◽  
Cycle Fatigue ◽  
Cast Aluminum ◽  
Staircase Method ◽  
Automotive Components ◽  
Aluminum Cylinder

In the paper fatigue specimens are extracted from different regions of cast aluminum cylinder heads produced by two foundries. A high strength region and a low strength region were identified within the cylinder head and the A356-T6 material locally characterized in terms of microstructure and defect population. High cycle fatigue testing according to a reduced staircase method was performed to determine the local fatigue strength at 107 cycles in the cylinder heads of the two foundries. The implications of the experimental observations are discussed.

Fatigue Designing of High Strength Steels Components Considering Aggressive Fuel Environment and Very High Cycle Fatigue Effects

2014 ◽  
Vol 783-786 ◽  
pp. 1845-1850
Author(s):  
Stephan Issler ◽  
Manfred Bacher-Hoechst ◽  
Steffen Schmid
Keyword(s):  
High Cycle Fatigue ◽  
Fuel Injection ◽  
Fatigue Testing ◽  
High Strength Steels ◽  
High Strength ◽  
Cycle Fatigue ◽  
Fatigue Reliability ◽  
Automotive Components ◽  
Very High Cycle Fatigue ◽  
Very High

Automotive components for injection systems are subjected to load spectra with up to 1E9 load cycles during the expected service life. However, fatigue testing with such a large number of cycles using original components is extremely time-consuming and expensive. A contribution for fatigue reliability assessment is available by the application of specimen testing and the transfer of the results to components including the verification by component spot tests.In this contribution very high cycle fatigue results in laboratory air and in ethanol fuel using notched specimens of high strength stainless steel are discussed. The influence of testing frequency was studied using ultrasonic and conventional test techniques. The validation and transfer of these accelerated testing results to components is one of the main challenges for a reliable fatigue designing.KeywordsVery High Cycle Fatigue (VHCF), automotive components, fuel injection, bio-fuels, corrosion fatigue, testing concepts, fatigue design concepts

Investigations on the Fatigue Property of the High-Strength and Toughness 211Z Casting Aluminium Alloy

2013 ◽  
Vol 423-426 ◽  
pp. 197-201
Author(s):  
Xiao Min Zhang ◽  
Jian Mao ◽  
Yun Che ◽  
Zhong Ke Zhang
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Testing Machine ◽  
High Strength ◽  
Cycle Fatigue ◽  
Fracture Appearance ◽  
Casting Aluminum Alloy ◽  
Casting Aluminum ◽  
Strength And Toughness

211Z is a new type of high strength and toughness Al-Cu-Mn casting aluminum alloy. With the aid of GPS-100 high-cycle fatigue testing machine and DDL100 multifunction tensile testing machine, conventional mechanics performance tests and high-cycle fatigue tests were carried out in this paper. The conventional mechanical property results show that the tensile strength is 477.5 MPa, the theory yield strength is 397.5 MPa and the elongation is 6.625%. Fatigue experiments were performed with load control at room temperature and R =-1 in ambient air. The tensile and compression fatigue strength is 130 MPa under ten million times fatigue test, and S-N fatigue life curve of this alloy was also given in the investigations. 211Z casting aluminum alloy possessing high fatigue strength can be attributed to the fact that it owns high strength and good plasticity simultaneously. The microstructure analysis of fatigue fracture appearance shows that, the fatigue crack initiation behavior of this aluminium alloys depends mainly on the region possessing defects under the surface, there has only one crack source, which means it is belongs to low nominal stress unidirectional bending. In the crack growth stage, the width of fatigue striations decreases with the increase of stress, and a few secondary cracks were found in this stage. When cracks finally losed stability, an instantaneous fracture occured in the investigated samples. Shear lips and dimples were found in the fracture appearance and the final fracture is belongs to ductile fracture.

Aluminum Cylinder Head High Cycle Fatigue Durability Including the Effects of Manufacturing Processes

2012 ◽  
Author(s):  
Xingfu Chen ◽  
Carlos Engler-Pinto ◽  
Michael King ◽  
Mei Li ◽  
Eben Prabhu ◽  
...  
Keyword(s):  
Cylinder Head ◽  
High Cycle Fatigue ◽  
Manufacturing Processes ◽  
Cycle Fatigue ◽  
Fatigue Durability ◽  
Aluminum Cylinder

Very High Cycle Fatigue Behavior and Thermographic Analysis of High Strength Steel

2010 ◽  
Vol 118-120 ◽  
pp. 948-951
Author(s):  
Chuang Shao ◽  
Claude Bathias ◽  
Danièle Wagner ◽  
Hua Tao
Keyword(s):  
Crack Initiation ◽  
High Strength Steel ◽  
High Cycle Fatigue ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
High Strength ◽  
Cycle Fatigue ◽  
Subsurface Crack ◽  
Very High Cycle Fatigue ◽  
Very High

Very high cycle fatigue behavior of high strength steel, were investigated using ultrasonic fatigue testing equipment at 20 kHz up to 109cycles. S-N curves at room temperature with different stress ratio (R=0.01 and R=0.1) was determined. The experimental results show that fatigue strength decrease with increasing number of cycles between 105 and 109. SEM examination of fracture surface reveals that fatigue damage was governed by the formation of cracks, and subsurface crack initiation was in the very long life range. The results shown that the portions of life attributed to subsurface crack initiation between 107 and 109 cycles are 99%.

scholarly journals Fatigue limit analysis of shot peened spring steel

2021 ◽  
Author(s):  
NohJun Myung ◽  
Liang Wang ◽  
Nak-Sam Choi
Keyword(s):  
Fatigue Strength ◽  
Fatigue Limit ◽  
Shot Peening ◽  
High Cycle Fatigue ◽  
High Strength ◽  
Spring Steel ◽  
Cycle Fatigue ◽  
Positive Effects ◽  
Fracturing Process ◽  
Fish Eye

This paper investigated the effect of shot-peening on fatigue strength of spring steel for the high cycle fatigue (HCF) and very high cycle fatigue (VHCF) to clarify the fatigue limit behavior of high strength spring steel during service life. Hourglass shape specimens made of spring steel (Si-Cr alloys) were prepared for the rotary bending fatigue test. Actual local stresses were quantitatively calculated to compensate for the stress amplitudes, through which it was clarified that the shot-peening had strongly positive effects on the HCF strength, but rather negative effect on the VHCF strength. The fish-eye fracturing process confirmed that most fish-eye fractures arose at sites deeper than the compressive residual stress zone, which did not prevent the creation of the fish-eye, and the fatigue strength improvement in the VHCF range could scarcely be shown as a result of the shot-peening treatment.

Assessment of Fatigue Reliability of Power Transmission Gearing for Aerospace Propulsion Applications

2013 ◽  
Author(s):  
Stefano Beretta ◽  
Mauro Filippini ◽  
Pietro Luccarelli ◽  
Andrea Motta ◽  
Giuseppe Pasquero
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Fatigue Crack Growth ◽  
High Cycle Fatigue ◽  
Power Transmission ◽  
High Strength ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Bending Fatigue ◽  
Metallic Inclusions

The fatigue strength in presence of inclusions is one of the main topics for the fatigue of high strength steels, especially the case hardened ones adopted for power transmission. In this paper we analyze the fatigue strength of carburized gears in presence of inclusions in order to develop the reliability assessment of a power transmission for aerospace propulsion. The high cycle fatigue properties of a high strength carburizing steel have been experimentally determined by conducting bending fatigue tests with specimens with artificial defects and a coherent model for the assessment of fatigue crack growth thresholds by taking into account of the residual stresses due to carburizing has been developed. In parallel, the distribution of non-metallic inclusions has been estimated by carrying out high cycle fatigue tests onto cylindrical smooth specimens and by inspection of mirror polished sections of the material. Eventually, by employing a simplified finite element model of a highly loaded gear wheel, the bending fatigue strength of gear teeth and the reliability of a turbo-propeller power transmission was determined by incorporating the fatigue crack growth thresholds, the measured residual stress profiles and the statistics of extreme non-metallic inclusions into a competing risks model applied to FE discretization.

scholarly journals Fatigue. Effects of Prestraining on High Cycle Fatigue Strength of High Strength Low Alloy TRIP Steels.

2001 ◽  
Vol 50 (10) ◽  
pp. 1091-1097 ◽  
Author(s):  
Sung-Moo SONG ◽  
Koh-ichi SUGIMOTO ◽  
Shinsuke KANDAKA ◽  
Asahiko FUTAMURA ◽  
Mitsuyuki KOBAYASHI ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
High Strength ◽  
Cycle Fatigue ◽  
Trip Steels
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