A comparative fatigue study of solder/electroless-nickel and solder/copper interfaces

2000 ◽  
Vol 15 (11) ◽  
pp. 2347-2355 ◽  
Author(s):  
Pi Lin Liu ◽  
Jian Ku Shang
Keyword(s):  
Growth Rate ◽  
Crack Growth ◽  
Fatigue Resistance ◽  
Fatigue Behavior ◽  
Intermetallic Phase ◽  
Electroless Nickel ◽  
Growth Mechanisms ◽  
High Crack ◽  
Solder Interface

The fatigue resistance of the interface between electroless–nickel and the eutectic tin–lead solder alloy was examined in the as-reflowed and aged conditions and compared to fatigue behavior of the copper/solder interface under the same conditions. In the as-reflowed state, the fatigue resistance of the solder/electroless-nickel interface was slightly superior to that of the solder/copper interface. However, after long-term aging, the fatigue resistance of the solder/electroless-nickel interface became far worse in the high crack growth rate regime. Examinations of interfacial microstructures and crack growth mechanisms indicated that the differences in fatigue resistance between the two interfaces were not directly related to the thickness of the intermetallic phase at the interface, as commonly believed, but were due to differences in crack growth mechanisms.

Small Scale Sour Fatigue Testing With Dense Phase Gases

2012 ◽  
Author(s):  
Weiwei Yu ◽  
Pedro M. Vargas ◽  
Ben Crowder ◽  
Sam Mishael ◽  
Ramgopal Thodla
Keyword(s):  
Growth Rate ◽  
High Pressure ◽  
Water Content ◽  
Crack Growth ◽  
Growth Rates ◽  
Fatigue Performance ◽  
Small Scale ◽  
Dense Phase ◽  
High Crack ◽  
Crack Growth Rates

One way generally accepted by industry to evaluate the effect of sour environment on fatigue performance of girth welds is by small scale testing in sour brines. These tests are commonly done at room temperature and pressure and therefore can only contain a maximum of 14.7psia of H2S in a gaseous phase. In comparison, very little has been published about fatigue performance in sour environments where negligible amounts or no water is present. Such condition can be found for pipelines serving in a “dry” sour environment (H2S and other gases in dense phase) with high H2S concentration. This paper documents both small scale fatigue crack growth rate (FCGR) tests and S-N fatigue tests in a dense phase sour environment with ultra-low water content and high H2S concentration under high pressure. Fatigue life reduction factors were calculated from FCGR approach (with the name crack growth acceleration factor, CGAF) and S-N approach (with the name knockdown factor), respectively. Industry understanding today is that water is necessary for accelerating fatigue crack growth. Quite opposite to the expected effect of water content on crack growth, even ultra-low water content (<450ppm) resulted in high crack growth rates. Crack growth rates were comparable among tests with various water contents, all ultra low. Through limited testing, no temperature dependency on crack growth rate was identified. It is postulated that hydrogen dissociation due to high pressure and high concentration may be the cause for high crack growth rates on the absence of water. Small scale S-N tests on smooth specimens reveal that fatigue performance in ultra-low-water sour environments is the same as in air. We find that the dry gas environment dose not attack the metal surface preserving the fatigue performance.

Growth Rate of Small Surface-Cracks in Age Hardening Cu-Ni-Si Alloy under Cyclic Stressing

2019 ◽  
Vol 827 ◽  
pp. 216-221
Author(s):  
Masahiro Goto ◽  
Takaei Yamamoto ◽  
Junichi Kitamura ◽  
Seung Zeon Han ◽  
R. Takanami ◽  
...  
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Fatigue Behavior ◽  
Material Constant ◽  
Age Hardening ◽  
Growth Data ◽  
Small Surface ◽  
Crystallographic Slip ◽  
Small Cracks

Stress-controlled fatigue tests were conducted on round-bar specimens to understand the fatigue behavior of precipitate-strengthened Cu–6Ni–1.5Si alloy. The cracks were initiated at the grain boundaries, followed by growth along the crystallographic slip planes in the adjacent grains. The crack growth data of plain specimens exhibited a large scatter, resulting in a difficulty of the measurement of crack growth rate. To evaluate the small-crack growth rate of the alloy, the plain specimens with a small blind hole as the crack starter were fatigued. The crack growth rate of small cracks from the hole was uniquely determined by a term σanl and the material constant, n, was 5.3. The term σanl with n = 5.3 was applied to the plain specimen, showing good applicability of the term to small cracks in the plain specimen.

scholarly journals EFFECT OF TEXTURE ON FATIGUE PROPERTIES OF AGE-HARDENED Al ALLOYS UNDER ULTRASONIC LOADING

2012 ◽  
Vol 06 ◽  
pp. 294-299
Author(s):  
HIRONORI MATSUSAKO ◽  
KOHJI KARIYA ◽  
NORIO KAWAGOISHI ◽  
QINGYUAN WANG ◽  
MASAHIRO GOTO
Keyword(s):  
Growth Rate ◽  
Crack Growth ◽  
Al Alloys ◽  
Fatigue Properties ◽  
Crack Growth Behavior ◽  
Loading Frequency ◽  
Slip Planes ◽  
Crack Tips ◽  
High Crack ◽  
The Difference

Effects of texture and loading frequency on the fatigue crack growth behavior of an extruded and a drawn Al alloys of 2017-T4 were investigated under ultrasonic loading frequency (20kHz) in the relative humidity of 25% and 85%, respectively. The extruded alloy has a marked texture of (111) orientation, but this specified orientation is not observed in the drawn alloy. Most of fatigue life was occupied by the growth life of small cracks in the both alloys regardless of humidity. In the low humidity, crack growth was retarded at about 0.3 mm in length in the both alloys. Although crack growth was accelerated by high humidity in the early growth process, there was no or little influence of humidity on the growth rate of cracks over about 0.3 mm in the both alloys. After the retardation of crack growth, fracture surfaces featured with many slip planes in the extruded alloy and many facets in the drawn one, respectively. The difference in growth mechanism between short cracks (<0.3 mm) and longer ones (>0.3 mm) was caused by the environment at crack tips due to high crack growth rate under ultrasonic loading, and that between the both alloys was related to the degree of texture.

Experimental Study on SCC Susceptibility of X60 Steel Using Full Pipe Sections in Near-Neutral pH Environment

2004 ◽  
Author(s):  
Bong Am Kim ◽  
Wenyue Zheng ◽  
G. Williams ◽  
M. Laronde ◽  
J. A. Gianetto ◽  
...  
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Loading Rate ◽  
Crack Depth ◽  
Metallographic Examination ◽  
Depth Measurement ◽  
Neutral Ph ◽  
Crack Tips ◽  
High Crack

Stress corrosion cracking (SCC) tests were performed using the pipe section buried in a clay type of soil with the pH adjusted to near-neutral range. Pipe specimens with various sizes of fatigue pre-cracks ahead of artifical notch tips on the outer surface were subjected to cyclic loading tests. Maximum level of hoop stress was 105% SMYS, and R-value (Ratio of minimum load to maximum load) was 0.5. Growth of cracks was observed from the fatigue crack tips. Fractographic and metallographic examination has confirmed the quasi-cleavage nature of the transgranular SCC that is typically observed in near-neutral pH SCC. Crack depth measurement using DCPD method revealed the relatively high crack growth rate up to 10−5 mm/s. Metallographic examinations showed the existence of many micro-cracks associated with MnS inclusions in the highly strained field ahead of the initial crack tips. The relatively high crack growth rate may be caused by MnS inclusions. The loading rate, dJ/dt, was calculated for each crack condition in order to correlate qualitatively the crack growth rate with the loading rate. J-integral was calculated through non-linear FEM analyses for semi-elliptical cracks based on the stress-strain relationships obtained from the tensile tests using the same X60 steel specimen. Linear relationship was then obtained between the crack growth rate and the loading rate, and therefore the possibility to predict crack growth rates for various loading condition in the field was demonstrated.

Fatigue Crack Prediction of LC9 with Corrosion Damage Considering Effect of Load Frequency

2013 ◽  
Vol 842 ◽  
pp. 374-377 ◽  
Author(s):  
Xu Dong Li ◽  
Zhi Tao Mu ◽  
Wen Sheng Sun
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Corrosion Fatigue ◽  
Fatigue Behavior ◽  
Corrosion Damage ◽  
Frequency Factor ◽  
Corrosion Fatigue Crack

Considering the degradation effect of corrosion damage on fatigue behavior of aero aluminum alloy, the present thesis made a research on corrosion fatigue crack growth rate. Taking into account the effect of load frequency on fatigue crack growth, a concept of corrosion fatigue frequency factor is proposed. Based on the fact that low frequency will lead to high corrosion fatigue crack growth rate, and frequency higher enough will make little difference between corrosion fatigue and pure mechanical fatigue behavior, an exponential expression of corrosion fatigue frequency factor is proposed. The crack growth rate prediction from proposed formula is proved to be in good agreement with experimental results for steadily extended corrosion fatigue crack.

Crack Growth Anomalies in Base Steel P91 and in HAZ

2005 ◽  
Vol 482 ◽  
pp. 383-386
Author(s):  
Jaroslav Balík ◽  
Miloš Janeček ◽  
Josef Pešička
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Crack Initiation ◽  
Crack Growth ◽  
Initiation Time ◽  
Material Degradation ◽  
Growth Anomalies ◽  
Base Steel

The growth of cracks in base steel P91 of 9Cr-1Mo class and in intercritical layer of HAZ is measured under creep coditions. For long term tests, a material degradation was detected consisting in an increase of crack growth rate and in a decrease of crack initiation time. An attempt is made to connect these effects with drop in ductility during thermomechanicalexposition.

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