Showing 4 results for Temper
H. Ghasemi Tabasi, A. H. Kokabi,
Volume 2, Issue 2 (11-2016)
Abstract
The aim of this study is to reach an increased service life for parts using in sour environment by weld overlaying process. In this investigation, two successive layers of ER410NiMo were clad on low alloy steel substrates. To reduce the likelihood of Hydrogen Induced Cracking (HIC) and producing stable hydrogen traps, Post Weld Heat Treatment (PWHT) was conducted. Microstructural analysis, X-ray diffraction studies, and mechanical tests show significant increase for austenite volume fraction after second stage of PWHT. In fact, not only two-stage PWHT reduce the samples hardness, but it also increases austenite volume fraction which is a more resistant microstructure against hydrogen cracking.
Hamid Gharaei, Mahdi Salehi, Mehran Nahvi, Behzad Sadeghian,
Volume 2, Issue 2 (11-2016)
Abstract
In this research, artificial neural network (ANN) and genetic algorithm (GA) were used in order to produce and develop the NiAl intermetallic coating with the best wear behavior and the most value of hardness. The effect of variations of current, voltage and gas flow on the hardness and wear resistance were optimized by ANN and GA. In the following, the optimum values of current, voltage and gas flow were obtained 90(A), 10(v) and 9 (Lit/min), respectively. Then, the wear behavior in the environment temperature and high temperature for optimized NiAl compound was compared with two other experimental samples.
N. Habibi, H. Eskandari,
Volume 5, Issue 2 (1-2020)
Abstract
Welded tubular joints are widely used in various industry structures for high efficiency subjected to pressure, bending and twisting.Welded structures are the main parts of structures, buildings, bridges, gas pipes, pressure vessels and power transmission equipment in the ship building, construction, oil, gas, petrochemical industries and power plants.A sample of pipe-welded joints is a X-tubular joint that has been investigated in this study.The main objective of the present work is to investigate the heat transfer and residual stress caused by the three-stage welding process in X-tubular joint made of St52 using Simufact Welding software.The welding process involves three welding steps using arc welding. The finite element model contains the thermal and mechanical properties of base metal and welding metal as a function of temperature.Also, advanced modeling tools such as mesh adaptation during the process and meshing compatible with the welding site, the birth and death technique of the element and the source of heat transfer have been used.Welding simulation showed that significant residual stresses were created in the joint after welding. Comparison of the results shows that the numerical results and empirical measurements are in good agreement with each other and the existing model can provide a good prediction of temperature distribution and stress control in this welding process.
M. Rostami, H. Khorsand,
Volume 6, Issue 1 (8-2020)
Abstract
The conventional eddy current method for non-destructive inspection of welding joints has limitations that can examine defects to a certain depth below the surface of the sample and is not suitable for determining deep defects. This limitation can be overcome using the SQUID superconducting sensors. The nonstoichiometric composition of YBCO due to its superconducting temperature and desired critical current density is widely used including the use of highly sensitive SQUID sensors. The properties and temperature of the superconducting compound are related to producing pure and homogeneous with a precise ratio of this non-stoichiometric compound in phase Y:123. In this study, the production of this high-temperature superconductor was carried out using a sol gel self-combustion process with nitrate forming elements and then produced powder analyzed by TGA, XRD, scanning electron microscopy, and EDX method and optimum conditions for production of Y:123 superconducting nanopowder were obtained by sol gel self-combustion method. In these conditions, the superconducting phase Y:123 was produced and the impurities were removed and on the other hand, the need for further thermal treatment and the costly annealing process were removed. Finally, optimal conditions for deposition of this compound on the substrate for producing the SQUID sensor were investigated and an optimal condition was presented to produce thin layer YBCO deposited by pulsed laser deposition method and patterned to produce SQUID High temperature Superconductor SQUID sensor. Finally the SQUID based NDT test for detecting sub-surfaces defects was investigated.
