A Mechanism for the Evolution of Hot Compression Cracking in Inconel 625 Alloy Ingot With Respect to Grain Growth

2020 ◽  
Vol 22 (6) ◽  
pp. 1901445
Author(s):  
Zhi Jia ◽  
Zexi Gao ◽  
Jinjin Ji
Author(s):  
German Cota-Sanchez ◽  
Lin Xiao

Abstract Inconel 625 is considered one of the candidate materials for reactor fuel cladding in the Canadian supercritical water reactor (SCWR) design. Gas tungsten arc welding (GTAW) is being evaluated as a joining technique for SCWR fuel cladding since this method is widely used to join components in the power and nuclear industry. During the GTAW process, the welding thermal cycle produces different types of microstructures in both the heat-affected zone (HAZ) and fusion zone (FZ) that affect the material's mechanical properties. A series of welding experiments at various weld conditions were performed using an automatic GTAW orbital process on Inconel 625 alloy tubing. Simple analytical heat conduction and grain growth models were developed to predict weld temperature profiles and metallurgical transformations. Weld characterization included mechanical tests, optical microscopy, scanning electron microscopy - energy dispersive spectroscopy (SEM-EDS) elemental analysis, and microhardness measurements. Weld microstructural characterization revealed that a characteristic dendritic structure was formed in the FZ, while the HAZ exhibited larger equiaxed grains than those found in the base material. SEM-EDS analysis showed no distinct alloying element segregation in both the HAZ and FZ. Welds produced with heat inputs of about 3.00 kJ/cm3 presented similar mechanical properties as those observed in the base material. In these welds, grain growth was homogenously minimized in the FZ. It is concluded that the effective welding heat input control can optimize the weld microstructure and the weld mechanical properties in Inconel 625 tubing used as Canadian SCWR reactor fuel cladding.


Author(s):  
Diego de Medeiros Barbosa ◽  
Leticia Helena Guimarães Alvarinho ◽  
Aristides Magri ◽  
Daniel Suyama

2020 ◽  
Vol 39 (1) ◽  
pp. 340-350
Author(s):  
Mingjing Wang ◽  
Song Zeng ◽  
Huihui Zhang ◽  
Ming Zhu ◽  
Chengxin Lei ◽  
...  

AbstractCorrosion behaviors of 316 stainless steel (316 ss) and Inconel 625 alloy in molten NaCl–KCl–ZnCl2 at 700°C and 900°C were investigated by immersion tests and electrochemical methods, including potentiodynamic polarization and electrochemical impedance spectroscopy. X-ray diffraction and scanning electron microscopy/energy dispersive spectroscopy were used to analyze the phases and microstructures of the corrosion products. Inconel 625 alloy and 316 ss exhibited high corrosion rates in molten chlorides, and the corrosion rates of these two alloys accelerated when the temperature increased from 700°C to 900°C. The results of the electrochemical tests showed that both alloys exhibited active corrosion in chloride molten salt, and the current density of 316 ss in chloride molten salt at 700°C was 2.756 mA/cm−2, which is about three times the value for Inconel 625 alloy; and the values of the charge transfer resistance (Rt) for Inconel 625 were larger than those for 316 ss. The corrosion of these two alloys is owing to the preferred oxidation of Cr in chloride molten salt, and the corrosion layer was mainly ZnCr2O4 which was loose and porous and showed poor adherence to metal.


Author(s):  
Xingmao Wang ◽  
Yutian Ding ◽  
Yubi Gao ◽  
Yuanjun Ma ◽  
Jianjun Chen ◽  
...  

2021 ◽  
Vol 15 (1) ◽  
pp. 7715-7728
Author(s):  
S. Madhankumar ◽  
K. Manonmani ◽  
V. Karthickeyan ◽  
N. Balaji

The ultimate strength is an important property of any material for the manufacturing of components. This paper utilized the laser beam welding (LBW), due to its smaller dimension, which produces lesser distortion and process velocity is higher. Inconel 625 alloy and duplex 2205 stainless steel is having higher strength and corrosive resistance properties. Due to the above-mentioned properties, it could be used in oil and gas storage containers, marine and geothermal applications. This research work presents an investigation of various input variable effects on the output variable (ultimate tensile strength) in LBW for dissimilar materials namely, Inconel 625 alloy and duplex 2205 stainless steel. The input variables for this research are the power of a laser, welding speed, and focal position. The experimental runs are developed with the help of design of experiment (DOE) and utilized statistical design expert software. The ultimate tensile strength on different runs is measured using a universal tensile testing machine. Then from a response surface methodology and ANOVA, the optimum value of ultimate tensile strength was determined to maximize the weld joint and bead geometry. Finally, the confirmation test was carried out, it reveals the maximum error of 0.912% with the predicted value. In addition, the microstructure of the weld beads was examined using optical microscopy.


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