scholarly journals Microstructure and Fracture Toughness of Fe–Nb Dissimilar Welded Joints

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 86
Author(s):  
Qiaoling Chu ◽  
Lin Zhang ◽  
Tuo Xia ◽  
Peng Cheng ◽  
Jianming Zheng ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Weld Metal ◽  
Thermal Cycle ◽  
Peak Load ◽  
Local Phase ◽  
Weld Formation ◽  
Lamellar Structures ◽  
Average Hardness ◽  
Radial Cracks

The relation between the microstructure and mechanical properties of the Fe–Nb dissimilar joint were investigated using nanoindentation. The weld metal consists mainly of Fe2Nb, α-Fe + Fe2Nb, Nb (s,s) and Fe7Nb6 phases. Radial cracks initiate from the corners of the impressions on the Fe2Nb phase (~20.5 GPa) when subjected to a peak load of 300 mN, whereas the fine lamellar structures (α-Fe + Fe2Nb) with an average hardness of 6.5 GPa are free from cracks. The calculated fracture toughness of the Fe2Nb intermetallics is 1.41 ± 0.53 MPam1/2. A simplified scenario of weld formation together with the thermal cycle is proposed to elaborate the way local phase determined the mechanical properties.

Effects of Gradation of Sand on the Mechanical Properties of Engineered Cementitious Composites

2011 ◽  
Vol 250-253 ◽  
pp. 374-378
Author(s):  
Ying Zi Yang ◽  
Yan Yao ◽  
Yu Zhu
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Peak Load ◽  
Drying Shrinkage ◽  
Bending Test ◽  
Cementitious Composites ◽  
Paper Test ◽  
Engineered Cementitious Composites ◽  
Load Peak ◽  
Fineness Modulus

Four-point bending test was employed to investigate the effects of gradation of sand on the mechanical properties of Engineered Cementitious Composites (ECC). The characteristics of ECC such as mid-span deflection, first cracking load, peak load and fracture toughness were obtained from the load-deflection curve. Effects of gradation of sand on fresh properties, compressive strength, flexural strength and drying shrinkage of ECC were also discussed in this paper. Test results shown that when the fineness modulus of sand in ECC was 1.0, the mid-span deflection and fracture toughness of ECC increased nearly 1.5 times and 2 times that of ECC with the sand fineness modulus of 2.97, respectively. With the sand getting finer, the more superplascitizer is needed and the crack width of ECC becomes smaller. The drying shrinkage of ECC with 2.97 and 1.0 fineness modulus of sand at 24 days was 8×10-4 and 15.6×10-4, respectively.

scholarly journals Fracture Mechanical Properties of Rocklike Materials Under Half Symmetric Loading

2017 ◽  
Vol 63 (4) ◽  
pp. 71-82
Author(s):  
Zhi Wang ◽  
Jiajia Zhou ◽  
Long Li
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Maximum Shear Stress ◽  
Peak Load ◽  
Crack Tip ◽  
Maximum Tensile Stress ◽  
Mode Ii ◽  
Loading Test ◽  
Mode Ii Fracture ◽  
Symmetric Loading

AbstractThe authors studied the fracture mechanical properties under half-symmetric loading in this paper. The stress distribution around the crack tip and the stress intensity factor of three kinds of notched specimens under half symmetric loading were compared. The maximum tensile stress σmax of double notch specimens was much greater than that of single notch specimens and the maximum shear stress τmax was almost equal, which means that the single notch specimens were more prone to Mode II fractures. The intensity factors KII of central notch specimens were very small compared with other specimens and they induced Mode I fractures. For both double notch and single notch specimens, KII was kept at a constant level and did not change with the change of a/h, and KII was much larger than KI. KII has the potential to reach its fracture toughness KIIC before KI and Mode II fractures occurred. Rock-like materials were introduced to produce single notch specimens. Test results show that the crack had been initiated at the crack tip and propagated along the original notch face, and a Mode II fracture occurred. There was no relationship between the peak load and the original notch length. The average value of KIIC was about 0.602 MPa×m1/2, and KIIC was about 3.8 times KIC. The half symmetric loading test of single notch specimens was one of the most effective methods to obtain a true Mode II fracture and determine Mode fracture toughness.

Effect of Thermal Treatment on the Hardness and Fracture Toughness of Sputter Deposited Bi-Layered Thin Films on Silicon

1998 ◽  
Vol 516 ◽  
Author(s):  
M. Manoharan ◽  
B. Narayanan ◽  
G. Muralidharan
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Intermediate Phase ◽  
Si Substrate ◽  
Microhardness Testing ◽  
Sputter Deposited ◽  
Cu Thin Film ◽  
Composite Hardness ◽  
Radial Cracks

AbstractMicrohardness testing is widely used for characterizing the mechanical properties of both bulk materials and thin films. Although this technique is usually associated with hardness measurements, fracture properties of brittle materials can also be studied with cracking associated with microhardness indentations. It is well known that the length of radial cracks emanating from the comers of indents made with Vickers and Berkovich indenters is related to the fracture toughness of the material. In the present study, microhardness testing has been used to follow the evolution of the mechanical properties of a 10 nm.Cu/200 nm. Ni(V)/300 nm. Al(Cu) thin film deposited on a Si substrate. Composite hardness and fracture toughness have been followed as a function of heat treatment temperatures and times and were found to be dependent on both variables. The roles of residual stresses, interdiffusion, and intermediate phase formation in the observed variation in hardness and fracture toughness are discussed.

Rosenhain Centenary Conference - 2. Design implications for materials selection 2.8 Weldability and toughness specifications for structural steels in Japan — with special reference to WES-155 and -156 Keynote speech

1976 ◽  
Vol 282 (1307) ◽  
pp. 258-263
Keyword(s):  
Mechanical Properties ◽  
Weld Metal ◽  
Stress Corrosion ◽  
Thermal Cycle ◽  
Structural Steels ◽  
Fusion Welding ◽  
Materials Selection ◽  
Keynote Speech ◽  
Welding Processes

The four papers to be covered in this Session concern weldability, toughness, corrosion, stress corrosion and specification requirements. The problem of weldability is dealt with in both the paper by Baker and by Kihara and coauthors. It is first important to decide exactly what is meant by the term weldability however, I would define weldability as the capability of different materials to be joined by a range of different welding processes with the object of giving satisfactory joints which meet the following objectives: 1. Free from harmful defects. 2. With adequate mechanical properties to carry loads which may be applied, that is with adequate strength and toughness. 3. With adequate resistance to long term environmental effects, e.g. creep, corrosion/ stress corrosion, and fatigue. Fusion welding gives rise to the possibility of a number of problems which may occur in any materials being welded, including the possible occurrence of defects, the presence of material in the weld metal when added fillers are used, changed material in the heat affected zone due to the thermal cycle, and the presence of residual stresses

Toughing of ZrAlN Film through Superlattice Design

2011 ◽  
Vol 291-294 ◽  
pp. 141-145 ◽  
Author(s):  
Jun Du ◽  
Xiao Ying Zhu ◽  
Zhi Hai Cai ◽  
Ping Zhang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Magnetron Sputtering ◽  
Elastic Recovery ◽  
Plastic Work ◽  
Indentation Method ◽  
Nano Indentation ◽  
Radial Cracks

Two kinds of magnetron sputtering ZrAlN films containing 23%atAl were deposited. The first was multicomponent ZrAlN film, the second was structure gradient and mulilayer film, named superlattice ZrAlN film. The microstructure was studied by FESEM, TEM , XRD, its mechanical properties were evaluated by nano-indentation method. The fracture toughness of films were determined from the length of ‘radial cracks’ on the applied diamond identer load 1.96N. the results show that, multicomponent ZrAlN film has hardness value of 35GPa, fracutre toughness value of 1.97MPa·m-0.5; while superlattice ZrAlN film has coresponding value of 40.1GPa and 3.17MPa·m-0.5. TEM image illustrates the superlattice ZrAlN film period is 2.5nm, nanoidentation test shows superlattice film has higher elastic recovery parameter and lower plastic work.

Effect of Welding Thermal Cycle on the Microstructure and Mechanical Properties in Multi-Pass Submerged-Arc Welding

2011 ◽  
Vol 314-316 ◽  
pp. 1163-1166 ◽  
Author(s):  
Zhong Yi Chen ◽  
Yong Lin Ma ◽  
Shu Qing Xing
Keyword(s):  
Mechanical Properties ◽  
Weld Metal ◽  
Arc Welding ◽  
Thermal Cycle ◽  
Welded Joint ◽  
Submerged Arc Welding ◽  
Welding Parameters ◽  
Microstructure And Mechanical Properties ◽  
Welding Thermal Cycle ◽  
Submerged Arc

To research effect of welding thermal cycle on the microstructure and mechanical properties of welded joint, two pieces of 60mm thick plates were welded together using automatic submerged-arc welding (SAW) method with suitable welding parameters. After 17 passes welding, the microstructures and phases of the welded joint was carefully observed and analyzed by using a Carl Zeiss optical microscope in different zones of welded joint, and the surface micro-hardness of the welded joint was measured systematically by using microscopic-hardness tester Lycra. Afterwards, the mechanical properties of the weld metals were measured through stretching. Through a series of measurements and observations, the welding experiment results indicate that effect of welding thermal cycle on the microstructure and mechanical properties of welding joint is great, the grains of the bottom of the weld metal are certainty smaller and more uniform, and the bottom of the weld metal have more excellent mechanical properties.

Microstructural and fractographic characterization of B4C-Al cermets tested under dynamic and static loading

1989 ◽  
Vol 47 ◽  
pp. 562-563
Author(s):  
Gyeung Ho Kim ◽  
Mehmet Sarikaya ◽  
D. L. Milius ◽  
I. A. Aksay
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Static Loading ◽  
Carbon Deposition ◽  
Full Density ◽  
Unique Combination ◽  
Strong Component ◽  
Reaction Products

Cermets are designed to optimize the mechanical properties of ceramics (hard and strong component) and metals (ductile and tough component) into one system. However, the processing of such systems is a problem in obtaining fully dense composite without deleterious reaction products. In the lightweight (2.65 g/cc) B4C-Al cermet, many of the processing problems have been circumvented. It is now possible to process fully dense B4C-Al cermet with tailored microstructures and achieve unique combination of mechanical properties (fracture strength of over 600 MPa and fracture toughness of 12 MPa-m1/2). In this paper, microstructure and fractography of B4C-Al cermets, tested under dynamic and static loading conditions, are described.The cermet is prepared by infiltration of Al at 1150°C into partially sintered B4C compact under vacuum to full density. Fracture surface replicas were prepared by using cellulose acetate and thin-film carbon deposition. Samples were observed with a Philips 3000 at 100 kV.

Characterization of interfaces in CVD-coated nicalon fiber-reinforced SiC

1989 ◽  
Vol 47 ◽  
pp. 556-557
Author(s):  
K.L. More ◽  
R.A. Lowden
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Chemical Vapor ◽  
Chemical Vapor Infiltration ◽  
Frictional Stress ◽  
Fiber Reinforced ◽  
Pull Out ◽  
Carbon Coated ◽  
Fiber Matrix

The mechanical properties of fiber-reinforced composites are directly related to the nature of the fiber-matrix bond. Fracture toughness is improved when debonding, crack deflection, and fiber pull-out occur which in turn depend on a weak interfacial bond. The interfacial characteristics of fiber-reinforced ceramics can be altered by applying thin coatings to the fibers prior to composite fabrication. In a previous study, Lowden and co-workers coated Nicalon fibers (Nippon Carbon Company) with silicon and carbon prior to chemical vapor infiltration with SiC and determined the influence of interfacial frictional stress on fracture phenomena. They found that the silicon-coated Nicalon fiber-reinforced SiC had low flexure strengths and brittle fracture whereas the composites containing carbon coated fibers exhibited improved strength and fracture toughness. In this study, coatings of boron or BN were applied to Nicalon fibers via chemical vapor deposition (CVD) and the fibers were subsequently incorporated in a SiC matrix. The fiber-matrix interfaces were characterized using transmission and scanning electron microscopy (TEM and SEM). Mechanical properties were determined and compared to those obtained for uncoated Nicalon fiber-reinforced SiC.

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