Effects of pre- and post-weld heat treatment conditions on microstructures of cast nickel based superalloys GTD-111 in the laser welding process

2019 ◽  
Vol 61 (8) ◽  
pp. 713-718
Author(s):  
Juthamate Jaruratchataphun ◽  
Panyawat Wangyao ◽  
Tanaporn Rojhirunsakool ◽  
Gobboon Lothongkum
Keyword(s):  
Heat Treatment ◽  
Laser Welding ◽  
Welding Process ◽  
Post Weld Heat Treatment ◽  
Treatment Conditions ◽  
Laser Welding Process ◽  
Weld Heat

scholarly journals Influence of post weld heat treatment on tensile properties of cold metal transfer (CMT) arc welded AA6061-T6 aluminium alloy joints

2019 ◽  
Vol 28 (1) ◽  
pp. 135-145 ◽  
Author(s):  
Addanki Ramaswamy ◽  
Sudersanan Malarvizhi ◽  
Visvalingam Balasubramanian
Keyword(s):  
Heat Treatment ◽  
Tensile Properties ◽  
Gas Metal Arc Welding ◽  
Weight Ratio ◽  
Welding Process ◽  
Metal Transfer ◽  
Post Weld Heat Treatment ◽  
Cold Metal Transfer ◽  
Cold Metal ◽  
Weld Heat

AbstractAluminium alloys of 6xxx series are widely used in the fabrication of light weight structures especially, where high strength to weight ratio and excellent weld-ability characteristics are desirable. Gas metal arc welding (GMAW) is the most predominantly used welding process in many industries due to the ease of automation. In this investigation, an attempt has been made to identify the best variant of GMAW process to overcome the problems like alloy segregation, precipitate dissolution and heat affected zone (HAZ) softening. Thin sheets of AA6061-T6 alloy were welded by cold metal transfer (CMT) and Pulsed CMT (PCMT). Among the two joints, the joint made by PCMT technique exhibited superior tensile properties due to the mechanical stirring action in the weld pool caused by forward and rearward movement of the wire along with the controllable diffusion rate at the interface caused by shorter solidification time. However, softening still exists in the welded joints. Further to increase the joint efficiency and to minimize HAZ softening, the joints were subjected to post weld heat treatment (PWHT). Approximately 10% improvement in the tensile properties had been observed in the PWHT joints due to the nucleation of strengthening precipitates in the weld metal and HAZ.

Engineering Critical Assessment of Post Weld Heat Treatment for Full-Encirclement Tees Greater Than 1.25 Inches

2019 ◽  
Author(s):  
Kolton Landreth ◽  
Qi Li ◽  
Raghav Marwaha
Keyword(s):  
Heat Treatment ◽  
Residual Stresses ◽  
Welding Process ◽  
Post Weld Heat Treatment ◽  
Critical Assessment ◽  
Material Strength ◽  
Mechanical Reinforcement ◽  
Element Analysis ◽  
Pipeline Design ◽  
Weld Heat

Abstract Full-encirclement split tee fittings for hot tapping and plugging (HT&P) wrap completely around the pipeline and are welded in place. The welded joint provides mechanical reinforcement of the pipe and branch. When full-encirclement hot tap tees are welded to pipelines 24 inches in diameter or larger, the header must often be at least 1.25 inches thick to pass the required calculations for reinforcement. This means the joint will require post weld heat treatment (PWHT) according to ASME B31.8 and CSA Z662. However, PWHT can be extremely dangerous and impractical, potentially elevating temperature to the point where material strength of the pressurized pipeline is compromised. An engineering critical assessment per ASME FFS-1/API 579 indicated PWHT may not be required for a full-encirclement hot tap tee over 1.25 inches thick. Specifically, research showed that the residual stresses developed during the welding process may not limit the design of a full-encirclement tee or lead to shorter pipeline design life. This paper illustrates how a “more rigorous analysis” per paragraph 802.2.2[b] of ASME B31.8 and paragraph 4.3.12.2 of CSA Z662 may help operators avoid the PWHT requirement. It discusses the finite element analysis (FEA) simulations researchers used to induce residual stresses in a carbon steel fitting. The residual stresses induced in the fitting were used as initial condition for plastic collapse and fatigue evaluations.

Effect of the FCAW Welding Process and Post Weld Heat Treatment on the Properties and Microstructure of the Weld Joints of Heat Treated 4330V Steel

2015 ◽  
Vol 809-810 ◽  
pp. 437-442
Author(s):  
Jacek Górka ◽  
Michał Miłoszewski
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Weld Metal ◽  
Heat Input ◽  
Large Diameter ◽  
Welding Process ◽  
Post Weld Heat Treatment ◽  
High Toughness ◽  
Interpass Temperature ◽  
Weld Heat

4330V is a high strength, high toughness, heat treatable low alloy steel for application in the oil, gas and aerospace industries. It is typically used for large diameter drilling parts where high toughness and strength are required. The research describes the effect of preheat temperature, interpass temperature, heat input, and post weld heat treatment on strength, hardness, toughness, and changes to microstructure in the weld joint. Welding with the lower heat input and no post weld heat treatment resulted in optimal mechanical properties in the weld metal. Austempering at 400 °C resulted in optimal mechanical properties in the HAZ. Increasing preheat and interpass temperature from 340 °C to 420 °C did not improve Charpy V-notch values or ultimate tensile strength in the weld metal or heat affected zones. The higher temperature increased the width of the heat affected zone. Austempering at 400 °C reduced HAZ hardness to a level comparable to the base metal. Both tempering and austempering at 400 °C for 10 hours reduced toughness in the weld metal.

Hot tensile and stress rupture behavior of friction welded alloy 718 in different pre-and post-weld heat treatment conditions

2014 ◽  
Vol 612 ◽  
pp. 414-422 ◽  
Author(s):  
R. Damodaram ◽  
S. Ganesh Sundara Raman ◽  
D.V.V. Satyanarayana ◽  
G. Madhusudhan Reddy ◽  
K. Prasad Rao
Keyword(s):  
Heat Treatment ◽  
Stress Rupture ◽  
Post Weld Heat Treatment ◽  
Alloy 718 ◽  
Treatment Conditions ◽  
Rupture Behavior ◽  
Weld Heat

Investigation of effect of post weld heat treatment conditions on residual stress for ITER blanket shield blocks

2016 ◽  
Vol 109-111 ◽  
pp. 747-751 ◽  
Author(s):  
Hun-Chea Jung ◽  
Sa-Woong Kim ◽  
Yun-Hee Lee ◽  
Seung-Wook Baek ◽  
Min-Su Ha ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Post Weld Heat Treatment ◽  
Treatment Conditions ◽  
Weld Heat

Weld Hardness Study of P91 Welded Pipes with Post Weld Heat Treatment for Elevated Temperature Application in Power Plants

2015 ◽  
Vol 1115 ◽  
pp. 503-508 ◽  
Author(s):  
Muhammad Sarwar ◽  
Mohd Amin bin Abd Majid
Keyword(s):  
Heat Treatment ◽  
Power Plant ◽  
Weld Metal ◽  
Creep Strength ◽  
Power Plants ◽  
Thermal Power ◽  
Base Material ◽  
Welding Process ◽  
Post Weld Heat Treatment ◽  
Weld Heat

The creep strength-enhanced ferritic (CSEF) steels are undergoing an encouraged use around the world especially in power plant construction. On construction sites, it has always been the target to have no problems in welded joints but premature failures are being encountered. The primary reason of these premature failures is found to be the improper heat treatment that is mandatorily carried out to achieve the required weld hardness. Weld hardness has close relationship with creep strength and ductility of the welded structures. Hence it is important for any weld to achieve certain level of weld hardness. This study aims at ascertaining the importance of Post Welding Heat Treatment (PWHT) in achieving the required hardness in creep-strength enhanced ferritic (CSEF) materials.The study was carried out on the welding of alloy steel ASTM A335 Gr. P-91 with the same base material (ASTM A335 Gr. P-91) by Gas Tungsten Arc Welding (GTAW) process using ER90S-B9 filler wire with pre-heat of 200oC (min) and inter-pass temperature of 300oC (max). After welding, the joints were tested for soundness with Radiography testing. Induction heating was used for heat treatment of P91 pipes during welding and post weld heat treatment. The effect of Post Weld Heat Treatment (PWHT) was investigated on the Weld metal and the Heat Affected Zones (HAZ) by hardness testing. It is perceived that the scattered and higher hardness values, more than 250HB in 2” P91 pipes in the weld metal and in the heat affected zones, can be brought into the lower required level, less than 250HB, with an effective post weld heat treatment at 760°C for 2hrs.It is concluded that PWHT is the most effective way of relieving the welding stresses that are produced due to high heat input in the welding process and to achieve the required level of hardness in the weld as well as in the heat affected zones (HAZ) in thermal power plant main steam piping.

scholarly journals Performance Evaluation of the Effects of Post Weld Heat Treatment on the Microstructure, Mechanical and Corrosion Potentials of Low Carbon Steel

2019 ◽  
Vol 44 (1) ◽  
pp. 41-47 ◽  
Author(s):  
Isiaka Oluwole Oladele ◽  
Davies Babatunde Alonge ◽  
Timothy Olakunle Betiku ◽  
Emmanuel Ohiomomo Igbafen ◽  
Benjamin Omotayo Adewuyi
Keyword(s):  
Heat Treatment ◽  
Carbon Steel ◽  
Low Carbon Steel ◽  
Welding Process ◽  
Post Weld Heat Treatment ◽  
Welding Parameters ◽  
Low Carbon ◽  
Corrosion Properties ◽  
Mechanical And Corrosion Properties ◽  
Weld Heat

The effect of Post Weld Heat Treatment (PWHT) on the microstructure, mechanical and corrosion properties of low carbon steel have been investigated. The welding process was conducted on butt joint using Manual Metal Arc Welding (MMAW) techniques at a welding voltage of 23 V and welding current of 110 A with the use of E6013 and 3.2 mm diameter as filler material. Heat treatment through full annealing was carried out on the welded low carbon steel. The mechanical properties (hardness, impact toughness and tensile properties) of the AW and PWHT samples were determined. The microstructure of the AW and PWHT samples was characterized by means of an optical microscopy. Corrosion behavior of the sample was studied in3.5 wt.% NaCl environment using potentiodynamic polarization method. The results showed that the AW samples has good combination of mechanical and corrosion properties. The microstructure revealed fine grains of pearlite randomly dispersed in the ferrite for the AW base metal (BM) sample while agglomerated and fine particle of epsilon carbide or cementite randomly dispersed on the ferritic phase of the heat affected zone (HAZ) and weld metal (WM), of the AW, respectively. The PWHT samples shows that the annealing process allow diffusion and growth of the fine grains into partial coarse grains of ferrite and pearlite which did not encourage improvement of the properties. Therefore, it was concluded that the welding parameters put in place during welding of the low carbon steel are optimum for quality weld.

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