scholarly journals Evaluation of Workability on the Microstructure and Mechanical Property of Modified 9Cr-2W Steel for Fuel Cladding by Cold Drawing Process and Intermediate Heat Treatment Condition

Metals ◽  
2018 ◽  
Vol 8 (3) ◽  
pp. 193 ◽  
Author(s):  
Hyeong-Min Heo ◽  
Jun-Hwhan Kim ◽  
Sung-Ho Kim ◽  
Jong-Ryoul Kim
Author(s):  
Hyeong-Min Heo ◽  
Jun-Hwhan Kim ◽  
Sung-Ho Kim ◽  
Jong-Ryoul Kim

In this study, we evaluated the cold drawing workability of two kinds of modified 9Cr-2W steel containing different contents of boron and nitrogen, depending on the temperature and time of normalizing and tempering treatments. Using ring compression tests at room temperature, the effect of intermediate heat treatment condition on workability was investigated. It was found that the prior austenite grain size can be changed by the austenite transformation, and the grain size increases with increasing temperature during normalizing heat treatment. Alloy B and Alloy N showed different patterns after normalizing heat treatment. Alloy N had higher stress than Alloy B, and the reduction in alloy N increased, while the reduction in alloy B decreased. Alloy B showed a larger number of initially formed cracks and a larger average crack length than Alloy N. Crack length and number increased proportionally in Alloy B as the stress increased. Alloy B had lower crack resistance than Alloy N due to boron segregation.


2018 ◽  
Vol 933 ◽  
pp. 68-77
Author(s):  
Yu Yuan Jiang ◽  
Xiao Xu Luo ◽  
Qing Chen ◽  
Ming Wei Zhao ◽  
Jian Sheng Lu ◽  
...  

ZL111 alloy foams with a porosity of 80% and an average pore diameter of 3.5 mm were fabricated using a two-step foaming process, and the effects of modification and heat treatment on their microstructure and mechanical property were studied. The results indicates that by Y&Sr modification, most of the eutectic silicon in the ZL111 alloy foam is transformed from plate-like into dot-like forms, and the average size of evenly distributed α-Al grain is reduced from 80~100μm to 30~40μm, which is more efficient than separate Y or Sr modifications. By combining Y and Sr modification and T6 heat treatment, the α-Al grain size of ZL111 alloy foam maintains its previous modified effect, eutectic silicon remains spherical and well-distributed, and CuAl2and Al9FeMg3Si5are dispersed homogeneously at the α-Al grain boundary. The Y&Sr modification and T6 heat treatment also significantly improved the compressive property of ZL111 alloy foam, when we compared them with the untreated ZL111 alloy foam. The compressive strength rises from 13.3 MPa to 22.6 MPa, the densification strain improves from 59.3% to 76.9%, and the energy absorption capacity increases from 4.87 MJ/m3to 13.77 MJ/m3.


2020 ◽  
Vol 188 ◽  
pp. 104213
Author(s):  
Ranjeet Kumar ◽  
Anand Varma ◽  
Y. Ravi Kumar ◽  
Himanshu Vashishtha ◽  
Jayant Jain ◽  
...  

2018 ◽  
Vol 917 ◽  
pp. 64-68
Author(s):  
Wiendartun ◽  
Jaenudin Kamal ◽  
Dadi Rusdiana ◽  
Andhy Setiawan ◽  
Dani Gustaman Syarief

A study on the effect of heat treatment condition on the characteristics of MnO2 added-Fe2TiO5 ceramics for NTC thermistor has been carried out. The ceramics were produced by pressing an homogenous mixture of Fe2O3 (local/ yarosite), TiO2 and MnO2 (2.0 mole %) powders in appropriate proportions to produce Fe2TiO5 based ceramics and sintering the pressed powder at 1050 °C for 3 hours in oxygen gas. Some sintered pellets were heat treated by heating them at 300 °C for 5, 15 and 25 minutes in Ar + 7% H2 gas. The XRD analyses showed that the Fe2TiO5 ceramics with and without heat treatment time had orthorhombic structure. No peak from second phase was observed from the XRD profiles. From the electrical characteristics data, it was known that the heat treatment could change the electrical characteristics of the Fe2TiO5 based-thermistor. The thermistor constant (B) and room temperature resistivity (ρRT) decreased with the increasing of heat treatment time. All ceramics made had thermistor characteristics namely B = 3459-7596 K and ρRT = 1.056-6936.062 MΩcm. Thermistor constant of the ceramics was relatively big, indicated that ceramics made from local iron oxide in this work fit the market requirement for NTC thermistor.


Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 629
Author(s):  
Anagh Deshpande ◽  
Subrata Deb Nath ◽  
Sundar Atre ◽  
Keng Hsu

Selective laser melting (SLM) is one of the most widely used additive manufacturing technologies. Fabricating nickel-based superalloys with SLM has garnered significant interest from the industry and the research community alike due to the excellent high temperature properties and thermal stability exhibited by the alloys. Haynes-282 alloy, a γ′-phase strengthened Ni-based superalloy, has shown good high temperature mechanical properties comparable to alloys like R-41, Waspaloy, and 263 alloy but with better fabricability. A study and comparison of the effect of different heat-treatment routes on microstructure and mechanical property evolution of Haynes-282 fabricated with SLM is lacking in the literature. Hence, in this manuscript, a thorough investigation of microstructure and mechanical properties after a three-step heat treatment and hot isostatic pressing (HIP) has been conducted. In-situ heat-treatment experiments were conducted in a transmission electron microscopy (TEM) to study γ′ precipitate evolution. γ′ precipitation was found to start at 950 °C during in-situ heat-treatment. Insights from the in-situ heat-treatment were used to decide the aging heat-treatment for the alloy. The three-step heat-treatment was found to increase yield strength (YS) and ultimate tensile strength (UTS). HIP process enabled γ′ precipitation and recrystallization of grains of the as-printed samples in one single step.


2020 ◽  
Vol 1012 ◽  
pp. 296-301
Author(s):  
Clélia Ribeiro de Oliveira ◽  
Eloá Lopes Maia ◽  
Solange T. da Fonseca ◽  
Marcelo Martins ◽  
Julián Arnaldo Ávila Díaz ◽  
...  

Superduplex stainless steel alloy exhibit high mechanical and corrosion resistance, which main industrial application is in the petrochemical industry. The manufacture and maintenance of such equipment usually involve welding processes, followed by post-welded heat treatment and it often becomes impossible to apply heat treatments. Thereby, the purpose of this work is to verify the effect of a post-welded heat treatment on shielded metal arc welding in steel grade ASTM A890/A890M - grade 6A. The microstructure in the as-welded condition consisted of austenite, secondary austenite, and ferrite phases and, the post-welded heat treatment condition exhibited only austenite and ferrite. The hardness in the melt zone reached values of 300 HV after welding and, the value was reduced to 260 HV in the post-welded heat treatment condition.


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