Cracks Repairing by Using Laser Additive and Subtractive Hybrid Manufacturing Technology

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Zifa Xu ◽  
Wentai Ouyang ◽  
Shaohui Jia ◽  
Junke Jiao ◽  
Mina Zhang ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Inconel 718 ◽  
Mechanical Test ◽  
Manufacturing Technology ◽  
Hybrid Manufacturing ◽  
Micro Hardness ◽  
Metallurgical Bonding ◽  
The Matrix ◽  
Deposition Direction

Abstract A laser additive and subtractive hybrid manufacturing technology was proposed to repair Inconel 718 cracks in this paper. Microstructures and the mechanical properties such as the micro-hardness, the tensile strength, and the friction-wear of the repair zone were investigated in detail. The microstructure analysis showed that a metallurgical bonding could be achieved between the repair zone and the matrix. The typically columnar and dendrite crystal appeared in the repaired zone, and the crystal epitaxial grew along the deposition direction, and the heat-affected zone in the groove boundary was coarse equiaxial crystal. The mechanical test result showed that the micro-hardness and tensile strength of the repaired tissue was about 87% and 89% of the original Inconel 718 wrought substrate. And, the wear resistance of the repaired zone was similar to that of the substrate. It was found that the surface quality of the repair zone for laser polishing is better than that for mechanical milling.

High Temperature Oxidation Behavior of NiAl and Ni3Al Argon Arc Claddings

2011 ◽  
Vol 189-193 ◽  
pp. 441-446
Author(s):  
Xiao Xia Tan ◽  
Zong De Liu
Keyword(s):  
High Temperature ◽  
High Temperature Oxidation ◽  
Steel Substrate ◽  
Temperature Oxidation ◽  
Metallurgical Bonding ◽  
The Matrix ◽  
Oxidation Properties ◽  
High Temperature Oxidation Behavior ◽  
16Mn Steel

NiAl and Ni3Al intermetallic compound claddings are prepared by argon arc cladding technology on the 16Mn steel substrate. These claddings were oxidized for 100 hours at 850 and the oxide quality of each sample was recorded every 10 hours. The results show that the NiAl and Ni3Al claddings have homogeneous structure and few defects, and form excellent metallurgical bonding with the matrix. The oxidation kinetics results show that, the oxidation weight gain rate of NiAl was more stable than Ni3Al and tended to zero earlier. Oxide layer spallation of Ni3Al cladding was more serious than that of NiAl cladding. Thus, NiAl argon arc cladding has the more excellent high temperature oxidation properties than Ni3Al argon arc cladding.

Effect of Equal Channel Angular Extrusion on the Microstructure and Mechanical Properties of Magnesium Alloy Containing Quasicrystallines

2005 ◽  
Vol 488-489 ◽  
pp. 589-592 ◽  
Author(s):  
Ming Yi Zheng ◽  
Xiao Guang Qiao ◽  
Shi Wei Xu ◽  
Kun Wu ◽  
Shigeharu Kamado ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Magnesium Alloy ◽  
Ultimate Tensile Strength ◽  
Equal Channel Angular Extrusion ◽  
Extrusion Direction ◽  
Micro Hardness ◽  
Angular Extrusion ◽  
The Matrix

Equal channel angular extrusion (ECAE) was applied to an extruded ZW1101 (Mg - 11wt%Zn - 0.9wt%Y) Mg alloy containing quasicrystallines. The as-extruded ZW1101 alloy had an initial grain size of about 12 µm and bands of quasicrystalline phases parallel to the extrusion direction. After the extruded alloy was subjected to ECAE processing, the grain size was refined to about 0.5 µm, and the quasicrystalline phases were further broken and dispersed in the matrix. After the ECAE processing, the micro-hardness and yield strength of the alloy were increased, however, the ultimate tensile strength and the ductility of the alloy were slightly decreased.

Microstructure and Mechanical Properties of New Particle-Disperse-Reinforced Mg Composite Mg- 6Al- 3B2O3- 1NaCl- 1CaCl2

2007 ◽  
Vol 546-549 ◽  
pp. 503-507
Author(s):  
Le Ping Bu ◽  
Shunsuke Tanaka ◽  
Masayuki Tsushida ◽  
Shinji Ando ◽  
Hideki Tonda
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Tensile Test ◽  
Optical Microscopy ◽  
Cast Alloy ◽  
Matrix Alloy ◽  
Al Alloys ◽  
The Other ◽  
Micro Hardness ◽  
The Matrix

In the present study, the conventional process of Compo-casting was carried and the microstructural and mechanical propertied were then investigated. The matrix alloy used was Mg- 6Al, and B2O3 was added into Mg-Al alloys was investigated at two levels of 3 and 6wt%. The other experimental materials were NaCl and CaCl2. The microstructures were of the samples analyzed with Optical Microscopy, SEM and XRD, and the mechanical properties were determined by micro-hardness and tensile test. The results showed that the mechanical properties of Mg- 6Al- 3B2O3- 1NaCl- 1CaCl2 increased and the microstructure was satisfactory, for a cast alloy, i.e.the tensile strength was 175MPa.

The Role of Reinforcing Particle Size in Tailoring Interfacial Microstructure and Wear Performance of Selective Laser Melting WC/Inconel 718 Composites

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Qimin Shi ◽  
Dongdong Gu ◽  
Kaijie Lin ◽  
Wenhua Chen ◽  
Mujian Xia ◽  
...  
Keyword(s):  
Temperature Gradient ◽  
Selective Laser Melting ◽  
Inconel 718 ◽  
Interfacial Microstructure ◽  
Interfacial Bonding ◽  
Wear Properties ◽  
Laser Melting ◽  
Metallurgical Bonding ◽  
The Matrix

In this paper, both traditional Inconel 718 parts and WC/Inconel 718 composites were fabricated by selective laser melting (SLM). The size of WC particles was observed to play a crucial role in determining the microstructural evolution, distortion, and microcracks around the WC particles, which inturn also affected the effective mechanical properties of WC/Inconel 718 composites. The use of the 5.25 μm diameter WC particles resulted in fine dendrites at the interface between the WC particle and the Inconel 718 matrix. This was attributed to the formation of an annular heat flow and radially arranged temperature gradient directions around the WC particle that increased the contact area between the matrix and the particle, thereby also improving the interfacial bonding. A sound metallurgical bonding at the interface was achieved with negligible distortion and microcracks due to a relatively uniform temperature distribution and temperature gradient (4.7 × 103 °C/mm) at the interface. This also explains the generation of dense and smooth interfacial bonding, which yielded a low average friction coefficient of 0.21. The wear properties were improved since grooves and spallation were reduced with the decrease of the WC size.

Microstructures and Properties of Y2O3/La2O3/Cu Composite by Internal Oxidation

2012 ◽  
Vol 236-237 ◽  
pp. 109-112
Author(s):  
Song Wang ◽  
Ming Xie
Keyword(s):  
Electrical Conductivity ◽  
Tensile Strength ◽  
Internal Oxidation ◽  
Spray Deposition ◽  
Micro Hardness ◽  
Arc Erosion ◽  
Hardness Tester ◽  
Atomization Spray ◽  
The Matrix ◽  
Erosion Surface

The 1.5%Y2O3/1.5%La2O3/Cu composite was prepared by oxygen and nitrogen atomization spray deposition technique and internal oxidation. The microstructures, hardness, strength, electrical conductivity and arc erosion surface of the composite were investigated by optical light microscope, scanning electron microscope, micro-hardness tester, tensile test and arc erosion experiment. The results show that, with the increasing of internal oxidation temperature, the grains of the composite grow up obviously. When the internal oxidation reaches to 1000°C, the matrix grains begin to appear annealing twins. The micro-hardness was 436HV, the ultimate tensile strength was 580MPa, yield tensile strength was 503MPa, elongation of alloy was 8.7% and the electrical conductivity was 87% IACS of the composite by internal oxidation at 1000°C for 2h.The arc erosion surface shows a large number of paste-like coagulum and bubbles. Introduction

Morphology of High-Performance Rigid-Rod Polymer Fibers and Molecular Composites

1989 ◽  
Vol 47 ◽  
pp. 338-339
Author(s):  
W.W. Adams ◽  
S. J. Krause
Keyword(s):  
Tensile Strength ◽  
High Performance ◽  
Liquid Crystalline ◽  
Molecular Level ◽  
Synergistic Effects ◽  
Tensile Modulus ◽  
Commercial Development ◽  
The Matrix ◽  
Molecular Composites ◽  
Rigid Rod

Rigid-rod polymers such as PBO, poly(paraphenylene benzobisoxazole), Figure 1a, are now in commercial development for use as high-performance fibers and for reinforcement at the molecular level in molecular composites. Spinning of liquid crystalline polyphosphoric acid solutions of PBO, followed by washing, drying, and tension heat treatment produces fibers which have the following properties: density of 1.59 g/cm3; tensile strength of 820 kpsi; tensile modulus of 52 Mpsi; compressive strength of 50 kpsi; they are electrically insulating; they do not absorb moisture; and they are insensitive to radiation, including ultraviolet. Since the chain modulus of PBO is estimated to be 730 GPa, the high stiffness also affords the opportunity to reinforce a flexible coil polymer at the molecular level, in analogy to a chopped fiber reinforced composite. The objectives of the molecular composite concept are to eliminate the thermal expansion coefficient mismatch between the fiber and the matrix, as occurs in conventional composites, to eliminate the interface between the fiber and the matrix, and, hopefully, to obtain synergistic effects from the exceptional stiffness of the rigid-rod molecule. These expectations have been confirmed in the case of blending rigid-rod PBZT, poly(paraphenylene benzobisthiazole), Figure 1b, with stiff-chain ABPBI, poly 2,5(6) benzimidazole, Fig. 1c A film with 30% PBZT/70% ABPBI had tensile strength 190 kpsi and tensile modulus of 13 Mpsi when solution spun from a 3% methane sulfonic acid solution into a film. The modulus, as predicted by rule of mixtures, for a film with this composition and with planar isotropic orientation, should be 16 Mpsi. The experimental value is 80% of the theoretical value indicating that the concept of a molecular composite is valid.

Effect of mechanical restraint on the rate of corrosion in concrete

1998 ◽  
Vol 25 (1) ◽  
pp. 81-86 ◽  
Author(s):  
N Hearn ◽  
J Aiello
Keyword(s):  
Mix Design ◽  
Concrete Repair ◽  
Accelerated Corrosion ◽  
One Dimensional ◽  
Mechanical Restraint ◽  
Corrosion Rates ◽  
Accelerated Corrosion Tests ◽  
The Matrix ◽  
The Relationship

Experimental work on prismatic concrete specimens was conducted to determine the relationship between mechanical restraint and the rate of corrosion. The current together with the changes in strain of the confining frame were monitored during the accelerated corrosion tests. The effect of mix design and cracking on the corrosion rates was also investigated. The results show that one-dimensional mechanical restraint retards the corrosion process, as indicated by the reduction in the steel loss. Improved quality of the matrix, with and without cracking, reduces the rate of steel loss. In the inferior quality concrete, the effect of cracking on the corrosion rate is minimal.Key words: corrosion, concrete, repair.

scholarly journals Investigation of the microstructure evolution in TP347HFG austenitic steel at 700°C and its characterization method

2021 ◽  
Vol 40 (1) ◽  
pp. 12-22
Author(s):  
Yuetao Zhang ◽  
Tingbi Yuan ◽  
Yawei Shao ◽  
Xiao Wang
Keyword(s):  
Austenitic Steel ◽  
Aging Time ◽  
Microstructure Evolution ◽  
Precipitate Phase ◽  
Dispersion Strengthening ◽  
Micro Hardness ◽  
Dispersed Particles ◽  
Nonlinear Ultrasonic ◽  
The Matrix ◽  
Solution Strengthening

Abstract This article reports the microstructure evolution in TP347HFG austenitic steel during the aging process. The experiments were carried out at 700°C with different aging time from 500 to 3,650 h. The metallographic results show that the coherent twin and incoherent twin are existed in the original TP347HFG grains, while they gradually vanished with the increase of the aging time. After aging for 500 h, a lot of fine, dispersed particles precipitated from the matrix, but they disappeared after aging for 1,500 h. When the aging time extend to 3,650 h, the precipitates appeared apparently coarse in TP347HFG steel, which include the M23C6 and σ phase; besides, the micro-hardness of TP347HFG also changes during the aging, which was closely related to the effect of dispersion strengthening and solution strengthening. The results of the nonlinear ultrasonic measurement reveal that the β′ of TP347HFG steel was also changed with the aging time. It first increased at 0–500 h, then reduced later, and increased finally at 1,500–3,650 h. The variation of β′ in TP347HFG was influenced by a combined effect of the twin microstructure and the precipitate phase, which indicate that the nonlinear ultrasonic technique can be utilized to characterize the microstructure evolution in TP347HFG.

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