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Acta Metallurgica Sinica (English Letters)
[SJR: 0.525] [H-I: 18] [5 followers] Follow

Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1006-7191 - ISSN (Online) 2194-1289
Published by Springer-Verlag

[2353 journals]

Effect of Stress Ratio on the Fatigue Crack Propagation Behavior of the
Nickel-based GH4169 Alloy
- Authors: Shen Ye; Jian-Guo Gong; Xian-Cheng Zhang; Shan-Tung Tu; Cheng-Cheng Zhang
  Pages: 809 - 821
  Abstract: Abstract The fatigue crack growth behavior of the newly developed GH4169 nickel-based alloy at a maximum stress of 700 MPa and different stress ratios was investigated in the present work employing the specimens with a single micro-notch at a frequency of 129 Hz at room temperature. The results demonstrate a typical three-stage process of fatigue crack propagation processing from the microstructurally small crack (MSC) stage to the physically small crack (PSC) stage, and finally to the long crack stage. The crack growth rate in the MSC stage is relatively high, while the crack growth rate in the PSC stage is relatively low. A linear function of crack-tip reversible plastic zone size was proposed to predict the crack growth rate, indicating an adequate prediction solution.
  PubDate: 2017-09-01
  DOI: 10.1007/s40195-017-0567-6
  Issue No: Vol. 30, No. 9 (2017)
Ratcheting Behavior of SA508-3 Steel at Elevated Temperature: Experimental
Observation and Simulation
- Authors: Jun Tian; Yu Yang; Li-Ping Zhang; Xue-Jiao Shao; Juan Du; Qian-Hua Kan
  Pages: 822 - 828
  Abstract: Abstract A series of monotonic uniaxial tensile tests, strain-controlled and stress-controlled cyclic tests of SA508-3 steel were conducted from 25 to 350 °C. Results showed that the steel exhibited temperature-dependent cyclic softening characteristic and obvious ratcheting behavior, and dynamic strain aging was observed in the range of 250–350 °C. Based on experimental observations, a temperature-dependent cyclic plastic constitutive model was proposed by introducing the nonlinear cyclic softening and kinematic hardening rules, and the dynamic strain aging was also considered into the constitutive model. Comparisons between experiments and simulations were carried out to validate the proposed model at elevated temperature.
  PubDate: 2017-09-01
  DOI: 10.1007/s40195-017-0588-1
  Issue No: Vol. 30, No. 9 (2017)
Formation of G-phase in 20Cr32Ni1Nb Stainless Steel and its Effect on
Mechanical Properties
- Authors: Xiao-Feng Guo; Ying-Ying Ni; Jian-Ming Gong; Lu-Yang Geng; Jian-Qun Tang; Yong Jiang; Xian-Kai Jia; Xin-Yu Yang
  Pages: 829 - 839
  Abstract: Abstract A series of tensile tests, Charpy impact tests, optical microscopy observations, and field emission-scanning electron microscopy examinations, were carried out to investigate the mechanical properties and microstructural evolution of 20Cr32Ni1Nb steel. Experimental results indicate that the as-cast microstructure of the steel typically consists of a supersaturated solid solution of austenite matrix with a network of interdendritic primary carbides (NbC and M 23C6). In the ex-service samples, large amounts of secondary carbides precipitate within austenite matrix. Besides the growth and coarsening of NbC and M 23C6 carbides during service condition, the Ni-Nb silicides known as G-phase (Ni16Nb6Si7) are formed at the interdendritic boundaries. The microstructural evolution results in the degradation of the mechanical properties of the ex-service steel. In addition, the precipitate rate of G-phase, depending in part on Si content, varies greatly for the 20Cr32Ni1Nb steel, which plays a key role in the long-term microstructural stability of the steel. Based on the X-ray diffraction data, time–temperature–transformation curve for the steel is obtained from the aged specimens.
  PubDate: 2017-09-01
  DOI: 10.1007/s40195-017-0589-0
  Issue No: Vol. 30, No. 9 (2017)
Micromechanical Analysis of In-Plane Constraint Effect on Local Fracture
Behavior of Cracks in the Weakest Locations of Dissimilar Metal Welded
Joint
- Authors: Jie Yang
  Pages: 840 - 850
  Abstract: Abstract In this work, a set of GTN (Gurson–Tvergaard–Needleman) parameters of the Alloy52M dissimilar metal welded joint (DMWJ) have been calibrated, and a micromechanical analysis of in-plane constraint effects on the local fracture behavior of two cracks, which located in the weakest regions of the DMWJ, has been investigated by the local approach based on the GTN damage model. The results show that the partition of the material and the variation of the q 2 parameter make the J-resistance curves obtained by numerical simulations close to the experimental values. The numerical J-resistance curves and crack growth paths are consistent with the experiment results, which show that the GTN damage model can incorporate the in-plane constraint effect. Furthermore, after the stress, strain and damage fields at the crack tip during the crack propagation process have been calculated, and the change of the J-resistance curves, crack growth paths and fracture mechanism with in-plane constraint have been analyzed.
  PubDate: 2017-09-01
  DOI: 10.1007/s40195-017-0599-y
  Issue No: Vol. 30, No. 9 (2017)
Oxidation Behavior of the Nickel-Based Superalloy DZ125 at
980 °C
- Authors: Ye-Bing Hu; Li Zhang; Cong-Qian Cheng; Peng-Tao Zhao; Guang-Ping Guo; Jie Zhao
  Pages: 857 - 862
  Abstract: Abstract The isothermal oxidation behavior of the nickel-based superalloy DZ125 was investigated at 980 °C through SEM/EDX and XRD. The weight loss process exhibited three periods—initial, transient and steady stages, which correspond to the formation of three layers on the surface. The outer layer was composed of NiO, whereas the intermediate layer mainly consisted of spinels and was accompanied with Ta-rich oxide. Alumina was evident as the inner continuous layer close to the substrate. The first formation of alumina was responsible for the initial stage of weight loss, and the formation of NiO and intermediate layer may dramatically affect on the transient and steady stage, respectively. The oxide scales effect on growth mechanism was discussed.
  PubDate: 2017-09-01
  DOI: 10.1007/s40195-017-0598-z
  Issue No: Vol. 30, No. 9 (2017)
Corrosion Behavior of the Ni–Cr–Fe Base Superalloy GH984G in a
Synthetic Coal Ash and Flue Gas Environment
- Authors: Guang-Ming Liu; Hua-Chun Yang; Qin Liang; Xiao-Chuan Yang; Shan-Ping Ren; Jian-Hang Huang
  Pages: 863 - 868
  Abstract: Abstract The corrosion behavior of the new Ni–Cr–Fe base superalloy GH984G in a synthetic coal ash and flue gas environments was studied at 700 °C. The results showed that the corrosion rate was slow during the initial corrosion stage, then followed by a stage of faster mass loss. During the corrosion test, the scale trended to spall slightly, resulting in the formation of corrosion pits on the sample surfaces. The main corrosion products were identified as NiFeCrO4 and a small amount of Cr2O3. The scale microstructure involved the presence of three corrosion layers. The outer layer contained Cr, Ni, Fe, O and a small amount of S. Many micro-cracks were detected in the Cr-rich intermediate oxide layer. The inner corrosion layer was thin and rich in S. Internal sulfidation and internal oxidation occurred in the substrate. Because of its relatively high Cr content, the GH984G superalloy exhibited a good corrosion resistance under the test conditions.
  PubDate: 2017-09-01
  DOI: 10.1007/s40195-017-0614-3
  Issue No: Vol. 30, No. 9 (2017)
Investigation of Work Hardening Behavior of Inconel X-750 Alloy
- Authors: Pei-Tao Hua; Wei-Hong Zhang; Lin-Jie Huang; Wen-Ru Sun
  Pages: 869 - 877
  Abstract: Abstract The constant strain rate uniaxial compression tests were conducted in this paper for studying the work hardening behavior and revealing the underlying microstructure evolution involved in the plastic response of the nickel-based Inconel X-750 alloy. The work hardening rate versus true strain plots of Inconel X-750 alloy resembled that of low-stacking-fault energy (SFE) alloys with distinct four stages. The dislocations were found in the planar arrangements at a strain of 0.1 located at the onset of stage II, and the dislocation density was increased and the planar arrangement configuration was partially destroyed at a strain of 0.36 located in stage III. It was unexpected that deformation twins were observed at a strain of 0.69 located in stage IV although the alloy has been classified into materials with a higher SFE value. The result is different with a similar study, in which the deformation twins were absent in Ni–Cr-based alloy Inconel 625 even when the strain was as high as 0.65. It was deemed that the low level of solution strengthening favored the deformation of matrix and the activation of slip system for twining in Inconel X-750 alloy. Unlike the low-SFE alloys that the twins were always formed at the end of stage I, the higher SFE delayed the twin formation to stage IV for Inconel X-750 alloy. The well-developed planar dislocation configuration gave rise to the stage II with a slightly decreasing rate, the collapse of planar dislocation arrangements caused the occurrence of stage III with an accelerated decreasing rate, and the twin formation led to the stage IV with a nearly constant work hardening rate.
  PubDate: 2017-09-01
  DOI: 10.1007/s40195-017-0607-2
  Issue No: Vol. 30, No. 9 (2017)
Low-Cycle Fatigue Properties of Nickel-Based Superalloys Processed by
High-Gradient Directional Solidification
- Authors: Z. D. Fan; D. Wang; C. Liu; G. Zhang; J. Shen; L. H. Lou; J. Zhang
  Pages: 878 - 886
  Abstract: Abstract The low-cycle fatigue (LCF) properties of DD10 (single-crystal) and DZ53 (columnar-grained) superalloys solidified by liquid–metal cooling (LMC) and high-rate solidification (HRS) processes have been systematically investigated. It was found that the LCF life of DZ53 solidified by LMC was obviously better than that solidified by HRS. In contrast, for DD10, LMC showed no remarkable influences on LCF properties at high temperature and only improved LCF properties at intermediate temperature. Microstructure examination showed that the cracks generally initiated at micropores in the subsurface at intermediate temperature. However, the cracks occurred on the surface due to oxidation, or persistent slip bands near script-MC at high temperature. Therefore, the benefits of LMC technique can be attributed to both of the reduced casting defects which significantly affect the LCF properties at intermediate temperature and the improved microstructural homogeneity which was strongly correlated to the LCF properties of alloys at high temperature.
  PubDate: 2017-09-01
  DOI: 10.1007/s40195-017-0563-x
  Issue No: Vol. 30, No. 9 (2017)
Transformation Mechanism of ( γ + γ ′) and the Effect of Cooling
Rate on the Final Solidification of U720Li Alloy
- Authors: Guang-Di Zhao; Guo-Liang Yang; Fang Liu; Xin Xin; Wen-Ru Sun
  Pages: 887 - 894
  Abstract: Abstract The transformation mechanism of (γ + γ′) was studied by analyzing the microstructure and elemental distribution of the U720Li samples heated at 1250 °C and cooled at the rates in the range of 1–100 °C/s. Although the (γ + γ′) is deemed to be formed by a eutectic reaction and has been called eutectic (γ + γ′), it was found in the present study that the (γ + γ′) precipitation begins with a peritectic reaction of (L + γ) → γ′, and develops by the eutectic reaction of L → (γ + γ′). The energy for the γ′ nucleation is low because the interfacial energy for the γ/γ′ interface is about one-tenth of the solid/liquid interface, and hence, the nucleation rate is high and the fine structure of (γ + γ′) is formed at the initial precipitation stage. The γ and γ′ in (γ + γ′) tend to grow into a lamellar structure because it is difficult for them to nucleate directly from the residual liquids, and hence, the γ′ precipitates naturally tend to grow divergently direction of the regions rich in Al and Ti, forming a fan-like structure of the (γ + γ′). As a result, the γ′ precipitates will coarsen finally because the space between them is enlarged. The solidification of the final residual liquids is a diffusion dependent process. When cooled at a higher rate, a higher degree of super cooling is reached and finally the solidification is finished by the pseudo-eutectic reaction of L → (γ + boride) and L → (γ + η), which can absorb Zr and B. When cooled at a rate low enough, most of the residual liquids are consumed by the (γ + γ′) growth due to the sufficient diffusion, and the boride and Zr-bearing phase are precipitated at a quasi-equilibrium state. Under this condition, Ti is depleted at the (γ + γ′) growth front. However, the η-Ni3Ti phase is formed there occasionally due to the boride precipitation, because the compositions of the two phases are complementary.
  PubDate: 2017-09-01
  DOI: 10.1007/s40195-017-0566-7
  Issue No: Vol. 30, No. 9 (2017)
Effect of Initial Goss Texture Sharpness on Texture Evolution and Magnetic
Properties of Ultra-thin Grain-oriented Electrical Steel
- Authors: Rui-Yang Liang; Ping Yang; Wei-Min Mao
  Pages: 895 - 906
  Abstract: Abstract In this study, high- and low-grade grain-oriented electrical steels were used as the initial materials to produce 0.08-mm-thick sheet with one-step cold-rolling method. Electron backscattering diffraction analysis technique and X-ray diffraction texture analysis technique were adopted to investigate the effect of initial Goss texture sharpness on texture evolution and magnetic properties of ultra-thin grain-oriented electrical steel. The results showed that primary recrystallization and secondary recrystallization were the main processes that occurred during annealing. The induced factors for secondary recrystallization of two grades samples were not consistent. The high-grade samples presented texture induction mechanism, while the low-grade samples revealed strong surface-energy induction mechanism. The initial Goss texture sharpness had a great impact on texture evolution and magnetic properties of ultra-thin grain-oriented electrical steel. The Goss texture component formed after primary recrystallization was stronger, and better magnetic properties were obtained at low frequencies. For low-grade samples, secondary recrystallization enhanced the intensity of Goss texture, and both grain size and texture contributed to better high-frequency magnetic properties after secondary recrystallization. By controlling the annealing process, the magnetic properties of low-grade products could be significantly improved, thus achieving conversion from low-grade to high-grade products.
  PubDate: 2017-09-01
  DOI: 10.1007/s40195-017-0610-7
  Issue No: Vol. 30, No. 9 (2017)
Dynamic Recrystallization Behavior and Processing Map Development of
25CrMo4 Mirror Plate Steel During Hot Deformation
- Authors: Peng Zhou; Qing-Xian Ma
  Pages: 907 - 920
  Abstract: Abstract The dynamic recrystallization behavior of 25CrMo4 steel was systematically investigated by compression deformation at different temperatures and strain rates on a Gleeble 1500 thermal mechanical simulation tester. The flow curves under different deformation conditions were obtained, and the effects of deformation temperature and strain rate on the appearance of the flow curves were discussed. Based on the experimental flow curves, the activation energy determined by regression analysis was Q = 337 kJ/mol, and the constitutive model was constructed. All the characteristic points of the flow curves were identified from the work hardening rate curves ( \(\theta = {\text{d}}\sigma /{\text{d}}\varepsilon \;{\text{vs}} \;\sigma\) ), which were derived from the flow curves. Then, the kinetics model of dynamic recrystallization was determined by combining the Avrami equation with the stress loss resulted from the dynamic recrystallization. With the aid of the kinetics model, the effect of strain on the efficiency of power dissipation was discussed. Furthermore, the optimum parameters for the forging process were determined based on the processing maps.
  PubDate: 2017-09-01
  DOI: 10.1007/s40195-017-0613-4
  Issue No: Vol. 30, No. 9 (2017)
Hot Workability of the as-Cast 21Cr Economical Duplex Stainless Steel
Through Processing Map and Microstructural Studies Using Different
Instability Criteria
- Authors: Jing Han; Jia-Peng Sun; Ying Han; Huan Liu
  Abstract: Abstract To develop a fundamental understanding of the flow behavior and optimal hot workability parameters of this material, the hot workability and deformation mechanisms of the as-cast 21Cr EDSS were studied using processing map technology combined with microstructure analysis and isothermal hot compression over the temperature range of 1000–1150 °C and strain rate range of 0.01–10 s−1. The processing maps and constitutive equation of peak stress were developed based on Prasad’s and Murty’s criteria. The results show that the processing maps exhibit a stable domain at 1000–1150 °C and 0.01–1 s−1. The instability domain is exhibited at high strain rates (≥1 s−1). This implies that Murty’s criterion can predict the unstable domain with high reliability. The detailed deformation mechanisms are also studied by microstructure observation, showing that the flow localization and microcracking are responsible for the flow instability.
  PubDate: 2017-09-13
  DOI: 10.1007/s40195-017-0647-7
Improvement of Mechanical Properties of Magnesium Alloy ZK60 by Asymmetric
Reduction Rolling
- Authors: Ling Wang; Yi-Quan Zhao; Hong-Mei Chen; Jing Zhang; Yan-Dong Liu; Yi-Nong Wang
  Abstract: Abstract The improvement of mechanical properties of ZK60 processed by asymmetric reduction rolling (ARR) was investigated in this paper. The grain refinement and basal texture intensity decrease were attributed to the introduction of shear stress produced by ARR process. Compared to conventional symmetrical rolled (SR) ZK60 alloys, ARRed ZK60 exhibited finer, more homogeneous grains and higher mechanical properties. The intensity of basal texture of ARRed ZK60 after annealing was lower than that of SRed ZK60 after annealing. ZK60 sheet with good combination of strength and ductility could be obtained by ARR process. The yield strength (YS) and ultimate tensile strength (UTS) of the ARRed ZK60 sheet were increased 150% and 91.3%, compared to those of SRed ZK60 sheet, from 80 to 200 MPa and from 140 to 264 MPa, respectively. Simultaneously, the elongation to failure increased by 68.75% in the ARR sheet (27%) when compared to that of the SR sheet (16%).
  PubDate: 2017-09-12
  DOI: 10.1007/s40195-017-0649-5
Improvement of Bonding Strength of Horizontal Twin-Roll Cast
Steel/Aluminum Clad Sheet by Electromagnetic Fields
- Abstract: Abstract Electromagnetic field is an available online method to increase bonding strength of clad sheet manufactured by horizontal twin-roll casting (HTRC). In this paper, an electric current pulse (ECP) and a complex field (static magnetic field (SMF) together with ECP) are exerted during HTRC of steel/aluminum clad sheet. The produced clad sheet has good appearance, and no visible defects exist at the bonding interface. The inter-diffusion zone at Fe/Al interface in ECP and SMF+ECP sheets is 3 and 4 μm, respectively, and the latter increases slightly compared with that in non-field sheet. The average peel strengths (APS) of ECP and SMF+ECP sheet are 14 and 21 N/mm, respectively, which increase by 2 and 9 N/mm compared with 12 N/mm of non-field sheet. The APS increment in SMF+ECP sheet is resulted from the increment of interface bonding spots and the enhancement of inter-diffusion zone width.
  PubDate: 2017-09-09
  DOI: 10.1007/s40195-017-0633-0
Dynamic Mechanical Behavior and Hypervelocity Impact Performance of an
Al-Based Nanocrystalline Alloy
- Abstract: Abstract In a wide strain rate range from 10−5 to 103 s−1, the deformation behavior of an Al-based nanocrystalline alloy was investigated. After fracture, the debris collected was used for statistical analysis, which is expected to reflect the profile of the fracture behavior of the alloy. The energy absorption of alloy at different strain rates was elucidated on account of mass distribution of debris. Based on the parameters obtained by the compression experiment at different strain rates, the numerical simulation experiment was carried out to evaluate the performance of Al-based nanocrystalline alloy as spacecraft shielding. The results suggest that Al-based nanocrystalline alloys have better shield performance than aluminum alloy under the identical areal density at velocity of 1–7 km/s. The better shield performance is attributed to high fracture strength, high hardness and low toughness of Al-based nanocrystalline alloy as compared with those of aluminum alloy.
  PubDate: 2017-09-08
  DOI: 10.1007/s40195-017-0644-x
Corrosion Performance of Carbon Steel in CO 2 Aqueous Environment
Containing Silty Sand with Different Sizes
- Abstract: Abstract Corrosion performance of carbon steel in CO2 aqueous environment containing silty sand with different sizes was investigated by immersion tests and electrochemical measurements. Silty sand could form an adsorption layer on steel surface in initial period, and the sand adsorption layer was turned into a mixture film of silty sand with corrosion product in last period. The adsorption layer in 325 mesh condition (large size) had the fewest pores for H2CO3 transport, exhibiting the highest cathodic current inhibition. In spite of little corrosion product, the sand adsorption film formed in 325 mesh condition induced the lowest corrosion rate. For 1000 and 5000 mesh silty sand, the sand adsorption layer had some pores for H2CO3 transport, leading to low cathodic current inhibition and much matrix dissolution. But the adsorption layer for 5000 mesh silty sand (small size) had the largest special surface area to accelerate heterogeneous precipitation of corrosion product FeCO3. Therefore, the mixture film in 5000 mesh condition was more compact, exhibiting stronger anodic inhibition and lower corrosion rate than those in 1000 mesh condition.
  PubDate: 2017-09-07
  DOI: 10.1007/s40195-017-0645-9
The Intrinsic Relationship Between Microstructure Evolution and Thermal
Fatigue Behavior of a Single-Crystal Cobalt-Base Superalloy
- Authors: Wei-Min Gui; Hong-Yu Zhang; Min Yang; Tao Jin; Xiao-Feng Sun; Qi Zheng
  Abstract: Abstract The intrinsic relationship between the microstructure evolution and thermal fatigue behavior of a single-crystal cobalt-base superalloy has been investigated. The thermal fatigue tests are performed cyclically between room temperature and 1050 °C using V-notch plate specimens. Three states of thermal fatigue specimens are selected: the as-cast, solutionized as well as aged states. The solution treatment is carried out at 1260 °C for 24 h, which results in the dissolution of most of interdendritic continuous primary carbides. The subsequent aging treatment is carried out at 1100 °C for 100 h after solution treatment, resulting in the precipitation of a profusion of chain- and point-like M 23C6 carbides in the matrix. The results indicate that the heat treatment can improve the thermal fatigue properties of the alloy and the effect of the solution treatment is more prominent than that of the aging treatment. The coarse and continuously distributed primary carbides in the as-cast state are changed into small and discontinuous distribution by heat treatment, which is the dominant factor in the improvement of thermal fatigue property. Additionally, the effect of oxidation behavior during thermal fatigue test on the thermal fatigue behavior is also studied.
  PubDate: 2017-09-06
  DOI: 10.1007/s40195-017-0646-8
Effect of K 2 TiO(C 2 O 4 ) 2 Addition in Electrolyte on the
Microstructure and Tribological Behavior of Micro-Arc Oxidation Coatings
on Aluminum Alloy
- Authors: Jian-Li Wang; Wei Yang; Da-Peng Xu; Xiao-Fei Yao
  Abstract: Abstract Micro-arc oxidation (MAO) coatings with different concentrations of K2TiO(C2O4)2 in the sodium silicate base electrolyte were prepared on 6061 aluminum alloy with the aim of promoting a better understanding of the formation mechanisms and tribological behaviors of the coatings. Scanning electron microscopy (SEM) assisted with energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and friction test were employed to characterize the MAO processes and microstructure of the resultant coatings. Results showed that the composition and microstructure of the coatings were significantly affected by the addition of K2TiO(C2O4)2. A sealing microstructure of MAO coating was obtained with the addition of K2TiO(C2O4)2. Ti element from K2TiO(C2O4)2 was only absorbed into the defects of micropores under surface energy in the early stage, while in the later stage, Ti element was predominant in the micropores and distributed on the coatings under plasma discharge to form TiO2. It was demonstrated that Ti and Si elements from the electrolyte could interact with each other during the MAO process and the interaction mechanism was systematically analyzed. Wear resistance of the MAO coatings with K2TiO(C2O4)2 addition was significantly improved compared with that of the MAO coatings without K2TiO(C2O4)2 addition.
  PubDate: 2017-08-30
  DOI: 10.1007/s40195-017-0641-0
Comparison of Microstructure and Residual Stress Between TIG and MAG
Welding Using Low Transformation Temperature Welding Filler
- Authors: Zhong-Yuan Feng; Xin-Jie Di; Shi-Pin Wu; Dong-Po Wang; Xiao-Qian Liu
  Abstract: Abstract A Cr–Ni type of low transformation temperature (LTT) welding filler was devised in the present study. The LTT weld microstructures of the tungsten inert gas (TIG) and metal active gas (MAG) weldings were investigated by using electron-backscattered diffraction and orientation imaging microscopy. The results showed that the LTT weld microstructures prepared by TIG and MAG weldings were primarily martensite with 17.5% and 8.0% retained austenite, respectively. The LTT weld metal using TIG welding had larger grain size than using MAG. In addition, based on the Taylor factor calculation, the weld metal using MAG welding was more competent in repressing fatigue crack initiation. Meanwhile, the high angle and coincidence site lattice grain boundaries were dominant in the LTT weld metal using MAG welding. Moreover, the hardness of the LTT weld metal using MAG welding was higher than that of using TIG. Based on heat input and phase transformation, finite element method was applied to analyzing the tensile residual stress (RS) reduction in welded joints prepared by both conventional and LTT welding fillers, respectively. The corresponding outcome confirmed that the LTT weld metal using MAG welding was more beneficial to tensile RS reduction.
  PubDate: 2017-08-30
  DOI: 10.1007/s40195-017-0642-z
Crack Initiation and Propagation Evaluation for Sn–5Sb Solder Under
Low-Cycle Fatigue
- Authors: Noritake Hiyoshi
  Abstract: Abstract In this study, a crack initiation and propagation behavior of Sn–5Sb lead-free solder under low-cycle fatigue is discussed. Cyclic push–pull loading tests with a single-hole specimen have been conducted at 313 K to investigate the crack initiation and propagation behavior of Sn-5Sb solder which has a higher melting point temperature than that of Sn–Ag–Cu solders. A fatigue life ratio correlates with the crack length within a small scatter. Crack initiates at the early stage, and almost all the life period is crack propagation process independent of strain range and strain rate. The crack propagation rate depends on the strain range and the strain rate. The adaptation of J-integral value for Sn–5Sb solder is also discussed. J-integral value is a suitable parameter for crack propagation rate evaluation.
  PubDate: 2017-07-26
  DOI: 10.1007/s40195-017-0605-4