Simultaneous improvement of strength and plasticity: Additional work-hardening from gradient microstructure

Shao, Chenwei; Zhang, P.; Zhu, Yansong; Zhang, Z.J.; Tian, Yanzhong; Zhang, Z.F.

doi:10.1016/j.actamat.2017.12.028

Cited by 177 publications

(35 citation statements)

References 56 publications

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“…f R a = 94.5 ∆U + 103.7. The stress and strain gradients have been reported to affect the free-surface roughness along with material strength in metal forming [21,29]. In the ISF process, besides stretching, a bending mechanism also operates and, as a result, a through-thickness stress gradient occurs [28,30].…”

Section: Influence Of Isf Strain On Free-surface Roughnessmentioning

confidence: 99%

On the Free-Surface Roughness in Incremental Forming of a Sheet Metal: A Study from the Perspective of ISF Strain, Surface Morphology, Post-Forming Properties, and Process Conditions

Al‐Ghamdi

Hussain

2019

Metals

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Due to absence of any supporting die, the free surfaces in incremental sheet forming (ISF) experience uneven deformation. This results in rough surfaces, possibly leading to the reduced service life of components. Therefore, it is necessary to analyze and quantify the effects of the application of strain on the free-surface roughness. Moreover, in order to control roughness, both on the free surface and the opposite contact surface, the nature of correlation between the two types of roughnesses needs to be identified by classifying the significance of different process conditions. The present work is a fundamental study to address these points. A series of specimens are produced by subjecting a metallic sheet to a range of ISF strains (13% to 98%). These specimens are then subjected to a number of characterization tests, namely roughness, uniaxial tension, and residual stress tests. The results reveal that the mean free-surface roughness increases non-linearly as the normal strain (stretching + bending) on the free surface increases (where strain state on the surface is as follows: ɛ1 = 0, ɛ2 > 0, γmax = ɛ2 and 1 and 2 are principal directions). The roughness also increases, although linearly, with the post-forming sheet strength, residual stress, and forming force, thereby showing that strain hardening has a direct influence on the roughness in a way that sheet strengthening is achieved at the cost of surface quality. The surface morphology reveals that the free surfaces contained orange peel, slip lines, and micro-voids, with density increasing with strain application, thus indicating the possible influence of tensile stresses on free surface deformation and roughening at an increasing degree with strain. Further analysis of roughness results discloses that the free-surface roughness and the contact-surface roughness are inversely related, because the responses of the two to ISF processing were mutually exclusive. Based on the obtained results, future research directions are also discussed.

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Section: Influence Of Isf Strain On Free-surface Roughnessmentioning

confidence: 99%

On the Free-Surface Roughness in Incremental Forming of a Sheet Metal: A Study from the Perspective of ISF Strain, Surface Morphology, Post-Forming Properties, and Process Conditions

Al‐Ghamdi

Hussain

2019

Metals

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“…Also, the current values were measured and the ±2 µA current was considered to be failure. To obtain specific data about the experimental unit, a vibration analyzer was used [25][26][27][28][29][30].…”

Section: No Solder Alloy Path Temperature Pret Vibrationmentioning

confidence: 99%

“…shows an interaction graphic of the soldering alloy and the vibration levels where the interaction between the level +1 of the soldering alloy and the level -1 of the vibration has lower time to failure[25][26][27][28][29][30][31].Time to failure (min) Interaction graphic for time to failure. Corresponds to the SnPB alloy.…”

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confidence: 99%

Reliable Method to Detect Alloy Soldering Fractures under Accelerated Life Test

et al. 2019

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In this research, we investigated the development and design of the Accelerated Life Test (ALT) and its approach to the waste of material. The development of a reliability model is based on the moment at which failure appears. The faults detected in welding joints during this research prevented proper current flow within electronic components and this interruption of current is considered a critical system failure. Minitab v18 was used to process data. Through statistical analysis, it was determined that the sample size was adequate with a 95% level of significance. A Shapiro Wilk analysis was carried out to determine the normality of the data, where a p-value of 0.1349 was obtained, which indicates that the data are normal. A Weibull analysis was applied, and it was observed that the data adjusted to the regression analysis and Weibull’s reliability distribution. The results showed that failure phenomena can occur during electronic assembly due to the values of R being too high and too close to each other. Significant issues included the welding alloy, temperature, and the interaction between the welding alloy and vibration. It is observed that with high temperature, the number of faults in the solder alloy used for tin and lead and for tin, silver, and copper were lower. 17 electronic assemblies with measures of 2 cm × 2 cm were fabricated, where components such as leads and electric resistance were used. The objective of analyzing this is to obtain the characteristics of the soldering alloy. Electronic components of this type are used worldwide in all types of electronic components, including: TVs, cell phones, tablet, computers, resistors, diodes, LEDs, and capacitors. For this work, the components were built based on an LED and a diode.

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“…So far, a vast amount of experimental study have shown that gradient structures have a positive effect on various mechanical properties of materials, such as high strength and ductility retention [16][17][18][19][20][21][22][23][24][25], better resistance of fatigue [26][27][28][29][30][31][32] and better wear resistance [33,34] et al By using the surface mechanical grinding treatment (SMGT) method for microstructure construction, Lu and Fang et al [18,19] prepared a gradient nano-grained (GNG) Cu film with spatial grain-size gradient on a coarse-grained (CG) Cu substrate. The samples exhibited much higher yield strength to that of CG counterpart but without compromising its ductility.…”

Section: Introductionmentioning

confidence: 99%

The influence of combined gradient structure with residual stress on crack-growth behavior in medium carbon steel

Wang

Yuan

Zhang

et al. 2019

Engineering Fracture Mechanics

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Simultaneous improvement of strength and plasticity: Additional work-hardening from gradient microstructure

Cited by 177 publications

References 56 publications

On the Free-Surface Roughness in Incremental Forming of a Sheet Metal: A Study from the Perspective of ISF Strain, Surface Morphology, Post-Forming Properties, and Process Conditions

On the Free-Surface Roughness in Incremental Forming of a Sheet Metal: A Study from the Perspective of ISF Strain, Surface Morphology, Post-Forming Properties, and Process Conditions

Reliable Method to Detect Alloy Soldering Fractures under Accelerated Life Test

The influence of combined gradient structure with residual stress on crack-growth behavior in medium carbon steel

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