Analysis of Notch Effect in Fracture Micromechanisms

2012 ◽  
Author(s):  
Sergio Cicero ◽  
Virginia Madrazo ◽  
Isidro Carrascal ◽  
Roman Cicero
Keyword(s):  
Fracture Toughness ◽  
Aluminum Alloy ◽  
Critical Radius ◽  
High Strength ◽  
Fracture Mechanisms ◽  
Notch Effect ◽  
Progressive Change ◽  
Load Bearing Capacity ◽  
Notched Specimens ◽  
Apparent Fracture Toughness

This paper presents an analysis of the notch effect in fracture micromechanisms. To this end, experimental results obtained in notched specimens are presented, together with the corresponding stress field at fracture and the SEM fractographies. The specimens comprise three materials (structural steel S275JR, high-strength aluminum alloy Al7075-T651 and Polymethyl methacrylate-PMMA) and notch radii varying from 0 mm (cracks) up to 2.5 mm. The results show how the stress relaxation caused by the notch effect is accompanied by a progressive change in the fracture mechanisms, from basically brittle ones in cracked conditions (for the three materials analyzed) to non-linear mechanisms observed for high notch radii, which explain the increase caused by the notch effect in both the load bearing capacity and the apparent fracture toughness. Also the concept of critical radius, that one below which the notch effect is negligible, is justified by SEM observations.

Analysing the Notch Effect Within the Ductile-to-Brittle Transition Zone of S275JR Steel

2013 ◽  
Author(s):  
Sergio Cicero ◽  
Tiberio García ◽  
Virginia Madrazo ◽  
Jorge Cuervo ◽  
Estela Ruiz ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Bearing Capacity ◽  
Transition Zone ◽  
Master Curve ◽  
Notch Effect ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Brittle Transition ◽  
Apparent Fracture Toughness ◽  
Ductile To Brittle Transition

This paper analyses the notch effect in ferritic-pearlitic steel S275JR in a range of temperatures within the material Ductile-to-Brittle Transition Zone (DBTZ). The notch effect is evaluated in terms of load-bearing capacity, apparent fracture toughness (modeled here using the Theory of Critical Distances) and fracture micromechanisms. The concept of Master Curve in notched conditions is also presented. To this end, experimental results obtained in S275JR notched specimens are presented, together with Scanning Electron Microscopy (SEM) fractographies. The analysis is performed at −50 °C, −30 °C and −10 °C, the material Transition Temperature (T0) being −26.1 °C, with the notch radii ranging from 0 mm (crack-type defects) up to 2.0 mm. The results show how the lower the temperature the larger the notch effect, and also that the evolution of both the load bearing capacity and the apparent fracture toughness is directly related to the evolution of fracture micromechanisms. Moreover, the proposed Master Curve in notched conditions has provided good predictions of the experimental results.

IMPALCO 770

Alloy Digest ◽  
1962 ◽  
Vol 11 (11) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
Shear Strength ◽  
Aluminum Alloy ◽  
Physical Properties ◽  
Tensile Properties ◽  
High Strength ◽  
Heat Treating ◽  
High Strength Aluminum Alloy ◽  
Structural Parts

Abstract IMPALCO 770 is a heat treatable, high strength aluminum alloy available in bar form for machining applications. It is recommended for highly stressed structural parts. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear strength as well as fracture toughness and fatigue. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Al-120. Producer or source: Imperial Aluminium Company Ltd.

FEDERATED F150.5

Alloy Digest ◽  
1975 ◽  
Vol 24 (11) ◽  
Keyword(s):  
Fracture Toughness ◽  
Aluminum Alloy ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
High Strength ◽  
Heat Treating ◽  
Alloying Elements ◽  
Light Weight ◽  
Temperature Performance

Abstract FEDERATED F150.5 is a heat-treatable aluminum alloy containing silicon and copper as the major alloying elements. It is recommended for high-strength, light-weight, pressure-tight castings. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on high temperature performance as well as casting, heat treating, machining, and joining. Filing Code: Al-219. Producer or source: Federated Metals Corporation, ASARCO Inc..

High Toughness Ceramic Laminates by Design of Residual Stresses

2001 ◽  
Vol 702 ◽  
Author(s):  
Nina A. Orlovskaya ◽  
Jakob Kuebler ◽  
Vladimir I. Subotin ◽  
Mykola Lugovy
Keyword(s):  
Fracture Toughness ◽  
Residual Stresses ◽  
Damage Tolerance ◽  
High Strength ◽  
Ceramic Composites ◽  
Tensile Stresses ◽  
High Toughness ◽  
Apparent Fracture Toughness ◽  
Layered Ceramics ◽  
Compressive Residual Stresses

ABSTRACTMultilayered ceramic composites are very promising materials for different engineering applications. Laminates with strong interfaces can provide high apparent fracture toughness and damage tolerance along with the high strength and reliability. The control over the mechanical behavior of laminates can be obtained through design of residual stresses in separate layers. Here we report a development of tough silicon nitride based layered ceramics with controlled compressive and tensile stresses in separate layers. We design laminates in a way to achieve high compressive residual stresses in thin (100-150 micron) Si3N4 layers and low tensile residual stresses in thick (600-700 micron) Si3N4-TiN layers. The residual stresses are controlled by the amount of TiN in layers with residual tensile stresses and the layers thickness. The fracture toughness of pure Si3N4(5wt%Y2O3+2wt%Al2O3) ceramics was measured to be of 5 MPa m1/2, while the apparent fracture toughness of Si3N4/Si3N4-TiN laminates was in the range of 7-8 MPa m1/2 depending on the composition and thickness of the layers.

scholarly journals Cracking and Toughening Mechanisms in Nanoscale Metallic Multilayer Films: A Brief Review

2018 ◽  
Vol 8 (10) ◽  
pp. 1821 ◽  
Author(s):  
Qing Zhou ◽  
Yue Ren ◽  
Yin Du ◽  
Dongpeng Hua ◽  
Weichao Han
Keyword(s):  
Fracture Toughness ◽  
High Strength ◽  
Plastic Instability ◽  
Multilayer Films ◽  
Fracture Mechanisms ◽  
Toughening Mechanisms ◽  
Individual Layer ◽  
Practical Applications ◽  
Mechanical Responses ◽  
The Individual

Nanoscale metallic multilayer films (NMMFs) have captured scientific interests on their mechanical responses. Compared with the properties of monolithic films, multilayers possess unique high strength as the individual layer thickness reduces to the nanoscale, which is benefited from the plentiful hetero-interfaces. However, NMMFs always exhibit a low fracture toughness and ductility, which seriously hinders their practical applications. While there have been reviews on the strengthening and deformation mechanisms of microlaminate, rapid developments in nanotechnology have brought an urgent requirement for an overview focused on the cracking and toughening mechanisms in nanoscale metallic multilayers. This article provides an extensive review on the structure, standard methodology and fracture mechanisms of NMMFs. A number of issues about the crack-related properties of NMMFs have been displayed, such as fracture toughness, wear resistance, adhesion energy, and plastic instability. Taken together, it is hoped that this review will achieve the following two purposes: (1) introducing the size-dependent cracking and toughness performance in NMMFs; and (2) offer a better understanding of the role interfaces displayed in toughening mechanisms. Finally, we list a few questions we concerned, which may shed light on further development.

X-ray Fractographic Study on Alumina and Zirconia Ceramics

1990 ◽  
Vol 34 ◽  
pp. 719-727 ◽  
Author(s):  
Sumio Tanaka ◽  
Yukio Hirose ◽  
Keisuke Tanaka
Keyword(s):  
Fracture Toughness ◽  
Residual Stress ◽  
Fracture Surface ◽  
High Strength Steels ◽  
High Strength ◽  
Fatigue Tests ◽  
Fracture Mechanisms ◽  
Zirconia Ceramics ◽  
X Ray ◽  
Fractographic Study

The residual stress left on the fracture surface is one of the important parameters in X-ray fractographic study. It has been used to analyze fracture mechanisms in fracture toughness and fatigue tests especially of high strength steels.In this paper, X-ray fractography was applied to brittle fracture of alumina (Al2O3) and zirconia (ZΓO2) ceramics.

scholarly journals Temperature Dependence of Fracture Characteristics of Variously Heat-Treated Grades of Ultra-High-Strength Steel: Experimental and Modelling

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5875
Author(s):  
Jaroslav Pokluda ◽  
Ivo Dlouhý ◽  
Marta Kianicová ◽  
Jan Čupera ◽  
Jana Horníková ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Temperature Dependence ◽  
High Stress ◽  
Stress Triaxiality ◽  
High Strength ◽  
Fracture Mechanisms ◽  
Temperature Range ◽  
Heat Treated ◽  
Shape Ratio ◽  
Standard Steel

The temperature dependence of tensile characteristics and fracture toughness of the standardly heat-treated low-alloyed steel OCHN3MFA along with three additionally heat-treated grades was experimentally studied. In the temperature range of ⟨−196; 22⟩ °C, all the additional heat treatments transferred the standard steel from a high- to ultra-high strength levels even with improved tensile ductility characteristics. This could be explained by a reduction of the inclusion content, refinement of the martensitic blocks, ductile retained austenite content, and homogenization of the shape ratio of martensitic laths as revealed by metallographic, X-ray, and EBSD techniques. On the other hand, the values of the fracture toughness of all grades were found to be comparable in the whole temperature range as the cause of a high stress triaxiality in the pre-cracked Charpy V-notch samples. The values of the fracture toughness of the standard steel grade could be predicted well using the fracture model proposed by Pokluda et al. based on the tensile characteristics. Such a prediction failed in the case of additionally heat-treated grades due to the different temperature dependence of the fracture mechanisms occurring in the tensile and fracture-toughness tests. While the tensile samples fractured in a ductile-dimple mode at all temperatures, the fracture-toughness specimens exhibited a transition from the ductile to quasi-brittle fracture mode with decreasing temperature. This transition could be interpreted in terms of a transfer from the model proposed by Rice and Johnson to the model of Tvergaard and Hutchinson.

IncoMAP Alloy Al-9052

Alloy Digest ◽  
1989 ◽  
Vol 38 (5) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Aluminum Alloys ◽  
Mechanical Alloying ◽  
Physical Properties ◽  
Tensile Properties ◽  
High Strength ◽  
Heat Treating ◽  
Corrosion Resistant

Abstract IncoMAP alloy Al-9052 is a high-strength, corrosion resistant aluminum alloy made by the mechanical alloying process. It is dispersion strengthened by oxides and carbides. Its density is 5% less than age hardenable aluminum alloys of comparable strength. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Al-296. Producer or source: Inco Alloys International Inc..

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