Creep Study for Fatigue Life Assessment of Two Lead-Free High Temperature Solder Alloys

AbstractCreep of two lead-free high temperature solder alloys, 95Sn-5Ag and 99Sn-1.0Cu was studied in this investigation. Room and high temperature creep tests were performed to examine deformation mechanisms and to establish mathematical models of creep deformation for the alloys. A state variable creep model was introduced to model both primary and secondary creep deformation of these two alloys which show a very significant primary creep. Fatigue life models of the alloys were established based on an energy-based failure criteria, which was deduced from variable strain amplitude tests at a constant strain rate of 0.003/sec, and from variable strain rates tests with two constant strain amplitudes of 0.005 and 0.01. Applications of the creep model includes determination of peak loads and hysteresis strain energy density in strain-controlled fatigue tests. It is demonstrated that the creep model can be very helpful to establish fatigue failure criteria and to assess fatigue lives of these two alloys.

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Creep Fatigue Life Assessment of a Pipe Intersection with Dissimilar Material Joint by Linear Matching Method

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.853.366 ◽

2016 ◽

Vol 853 ◽

pp. 366-371

Author(s):

Daniele Barbera ◽

Hao Feng Chen ◽

Ying Hua Liu

Keyword(s):

High Temperature ◽

Fatigue Life ◽

Direct Method ◽

Life Assessment ◽

Dissimilar Material ◽

Matching Method ◽

Fatigue Life Assessment ◽

Creep Fatigue ◽

The Impact ◽

Linear Matching Method

As the energy demand increases the power industry has to enhance both efficiency and environmental sustainability of power plants by increasing the operating temperature. The accurate creep fatigue life assessment is important for the safe operation and design of current and future power plant stations. This paper proposes a practical creep fatigue life assessment case of study by the Linear Matching Method (LMM) framework. The LMM for extended Direct Steady Cycle Analysis (eDSCA) has been adopted to calculate the creep fatigue responses due to the cyclic loading under high temperature conditions. A pipe intersection with dissimilar material joint, subjected to high cycling temperature and constant pressure steam, is used as an example. The closed end condition is considered at both ends of main and branch pipes. The impact of the material mismatch, transitional thermal load, and creep dwell on the failure mechanism and location within the intersection is investigated. All the results demonstrate the capability of the method, and how a direct method is able to support engineers in the assessment and design of high temperature component in a complex loading scenario.

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Experimental and numerical fatigue life assessment of SAC305 solders subjected to combined temperature and harmonic vibration loadings

Soldering & Surface Mount Technology ◽

10.1108/ssmt-10-2019-0030 ◽

2020 ◽

Vol 32 (3) ◽

pp. 181-187

Author(s):

Mohammad Gharaibeh

Keyword(s):

Fatigue Life ◽

Compound Layer ◽

Harmonic Vibration ◽

Life Assessment ◽

Lead Free ◽

Intermetallic Compound Layer ◽

Loading Test ◽

Content Type ◽

Vibration Loading ◽

Lead Free Solders

Purpose This paper aims to investigate the fatigue life performance of SAC305 ball grid array solders under combined temperature and harmonic vibration loading conditions. Design/methodology/approach Fatigue tests were performed using a sine dwell with resonance tracking vibration and temperature loading experiment. Finite element stress analysis was also performed to help in understanding the observed failure trends. Findings Fatigue test results showed that the lead-free solders tend to fail quickly in higher temperatures and higher vibration loading test conditions. The failure analysis results revealed that in low temperatures, the solder cracks are initiated and propagated at the package side. However, in high temperatures, the cracks are observed at the board side of the interconnect. In all conditions, the cracks are propagated throughout the intermetallic compound layer. Originality/value In the published literature, there is a lack of data in the area of fatigue assessment of lead-free solders under combined temperature and vibration loadings. This paper provides useful insights into combined thermal/vibration fatigue, i.e. reliability behavior of lead-free solder joint types.

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Assessment of Fatigue Life for High-Temperature Pipeline Welds Using X-Ray Diffraction Technique

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.353-358.130 ◽

2007 ◽

Vol 353-358 ◽

pp. 130-133

Author(s):

Keun Bong Yoo ◽

Jae Hoon Kim

Keyword(s):

High Temperature ◽

Fatigue Life ◽

Fatigue Damage ◽

Power Plants ◽

Low Cycle Fatigue ◽

Diffraction Method ◽

Life Assessment ◽

Fatigue Properties ◽

X Ray Diffraction ◽

X Ray

The objective of this study is to examine the feasibility of the X-ray diffraction method for the fatigue life assessment of high-temperature steel pipes used for main steam pipelines, re-heater pipelines and headers etc. in power plants. In this study, X-ray diffraction tests were performed on the specimens simulated for low cycle fatigue damage, in order to estimate fatigue properties at the various stages of fatigue life. As a result of X-ray diffraction tests, it was confirmed that the full width at the half maximum (FWHM) decreased with an increase in the fatigue life ratio, and that the FWHM and the residual stress due to fatigue damage were algebraically linearly related to the fatigue life ratio. From this relationship, a direct assessment of the remaining fatigue life was feasible.

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Effect of Sb additions on the creep behaviour of low temperature lead-free Sn–8Zn–3Bi solder alloy

Soldering & Surface Mount Technology ◽

10.1108/ssmt-05-2020-0023 ◽

2020 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Guang Ren ◽

Maurice Collins

Keyword(s):

Low Temperature ◽

Solder Alloy ◽

Creep Behaviour ◽

Lead Free ◽

Coefficient Of Determination ◽

Secondary Creep ◽

Lead Free Solder ◽

Solder Alloys ◽

Content Type ◽

Free Solder

Purpose This paper aims to investigate the creep behaviour of the recently developed Sn–8Zn–3Bi–xSb (x = 0, 0.5, 1.0 and 1.5) low temperature lead-free solder alloys. Design/methodology/approach An in-house compressive test rig was developed to perform creep tests under stresses of 20–40 MPa and temperature range 25°C–75 °C. Dorn power law and Garofalo hyperbolic sine law were used to model the secondary creep rate. Findings High coefficient of determination R2 of 0.99 is achieved for both the models. It was found that the activation energy of Sn–8Zn–3Bi solder alloy can be significantly increased with addition of Sb, by 60% to 90 kJ/mol approximately, whereas the secondary creep exponent falls in the range 3–7. Improved creep resistance is attributed to solid solution strengthening introduced by micro-alloying. Creep mechanisms that govern the deformation of these newly developed lead-free solder alloys have also been proposed. Originality/value The findings are expected to fill the gap of knowledge on creep behaviour of these newly developed solder alloys, which are possible alternatives as lead-free interconnecting material in low temperature electronic assembly.

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