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An investigation of the densification and microstructural evolution of M2/316L stepwise graded composite during co-sintering
, Article Journal of Materials Science ; Volume 43, Issue 1 , 2008 , Pages 55-63 ; 00222461 (ISSN) ; Simchi, A ; Kokabi, A. H ; Sharif University of Technology
2008
Abstract
The densification and microstructural evolution during co-sintering of M2 tool steel/316L stainless steel composite layers with and without boron addition was studied. A pressureless sintering method in conjunction with a powder layering technique was used to fabricate the stepwise graded composite layers. Isothermal and non-isothermal sintering response of the individual and composite layers was examined and the microstructural features of the bonding zone were studied. Shear strength and microhardness of the bonding zone were also measured. It was shown that an enhanced densification is obtained in the composite layers due to (i) sintering shrinkage incompatibility between two steels, (ii)...
Effect of solidification mechanism on microstructure and mechanical properties of joint in TLP bonded Al2024-T6 alloy
, Article Science and Technology of Welding and Joining ; Volume 16, Issue 2 , Nov , 2011 , Pages 174-180 ; 13621718 (ISSN) ; Ekrami, A ; Kokabi, A. H ; Sharif University of Technology
2011
Abstract
Transient liquid phase (TLP) bonding of Al2024-T6 alloy, using gallium (Ga) interlayer, has been investigated. Bonding process was carried out at 470°C for 6 min, and homogenising temperature and time were 495°C and 2 h respectively. Conventional TLP bonding using Ga interlayer was not an appropriate method for joining of Al2024. In this method, the boundary between two Al2024 specimens was not fully eliminated during bonding because of solidification with planar front. In addition, bonding zone was depleted of copper, and as a result, tensile and shear strength of joint decreased to 200 and 110 MPa respectively. TLP bonding under temperature gradient offered very good results in bonding of...
Transient liquid phase bonding of FSX-414 superalloy at the standard heat treatment condition
, Article Materials Characterization ; Volume 66 , 2012 , Pages 38-45 ; 10445803 (ISSN) ; Ekrami, A ; Sharif University of Technology
2012
Abstract
The as-cast samples of FSX-414 Co-based superalloy were heat treated at the standard solution and aging heat treatment cycles. Specimens for joining were cut from the as-cast ingot. Transient liquid phase (TLP) bonding was carried out at the standard solution cycle, using MBF-30 interlayer. Also, bonded specimens were homogenized at the standard aging condition. The microstructure of the as-cast, heat treated and TLP bonded specimens were studied. These studies showed that the non-uniform distributed carbides of the as-cast specimen were replaced by uniform ones during the heat treatment. Eutectic M 23C 6 carbides were observed in all specimens. Due to the complete isothermal solidification,...
Failure analysis of bolted joints in foam-core sandwich composites
, Article Journal of Reinforced Plastics and Composites ; Volume 27, Issue 15 , 2008 , Pages 1635-1647 ; 07316844 (ISSN) ; Moslemian, R ; Afshin, M ; Nazemi, M. H ; Sharif University of Technology
2008
Abstract
This study represents an effort to predict the bearing strength, failure modes, and failure load of bolted joints in foam-core sandwich composites. The studied joints have been used in a light full composite airplane. By using solid laminates, a new design for the joint zone is developed. These solid laminates include a number of glass plies with total thickness equal to core thickness. The effect of solid laminate size and interface angle of foam-solid laminate in the bonding zone on the bearing strength, failure loads and type of modes are investigated. The numerical study is performed using 3D FEM in ANSYS commercial code. Tsai-Wu failure criterion is used in the failure analysis. The...
Co-sintering of M2/17-4PH powders for fabrication of functional graded composite layers
, Article Journal of Composite Materials ; Volume 44, Issue 4 , 2010 , Pages 417-435 ; 00219983 (ISSN) ; Simchi, A ; Sharif University of Technology
2010
Abstract
Stepwise-graded composite layer of M2 tool stel and 17-4PH stainless steel was fabricated by a simple powder layering technique and the isothermal and nonisothermal sintering response of the bilayer were examined. It was shown that the materials exhibit poor compatibility during co-sintering, i.e., the amount of mismatch shrinkage is significant. An improved compatibility was obtained by adding 0.2 wt% B to the stainless steel powder. Formation of relatively dense layer at the bonding zone indicated an enhanced densification rate at the interface. Microstructural studies showed formation of a ferritic interface in M2/17-4PH composite and elongated grains with an intergranular boride phase...