TEM Investigations of the Microstructure of 7CrMoVTiB10-10 Steel Weld Metal

2015 ◽  
Vol 231 ◽  
pp. 101-106
Author(s):  
Krzysztof Pańcikiewicz ◽  
Anna Zielińska-Lipiec
Keyword(s):  
Heat Treatment ◽  
Chemical Composition ◽  
Weld Metal ◽  
Important Implication ◽  
Post Weld Heat Treatment ◽  
Steel Weld ◽  
Technological Properties ◽  
Cooling Conditions ◽  
Steel Weld Metal ◽  
Weld Heat

7CrMoVTiB10-10 (T24) steel is recommended for fabrication of boiler components such as water walls, water panels or headers without post weld heat treatment (PWHT). The chemical composition of this steel and cooling conditions after welding influence the susceptibility to cracking in weld metal during and after welding. TEM investigations showed that in the as-welded microstructure mixtures of bainite and martensite were dominating. This has an important implication for technological properties.

Post-weld Heat Treatment and Groove Angles Affect the Mechanical Properties of T92/Super 304H Dissimilar Steel Weld Joints

2018 ◽  
Vol 37 (7) ◽  
pp. 649-654 ◽  
Author(s):  
Wang Shuo ◽  
Wei Limin ◽  
Cheng Yi ◽  
Tan Shuping
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Weld Metal ◽  
Arc Welding ◽  
Post Weld Heat Treatment ◽  
Steel Weld ◽  
Dissimilar Weld ◽  
Weld Joints ◽  
Gas Tungsten Arc ◽  
Weld Heat

AbstractThe microstructures and mechanical properties of dissimilar weld joints between T92 and Super 304H steels were investigated. Dissimilar weld joints with four groove angles were constructed using gas tungsten arc welding. The results showed that post-weld heat treatment improved the mechanical properties of the dissimilar weld joints. The optimal groove angle for T92/Super 304H dissimilar weld joints was found to be 20°, considering mechanical properties. Furthermore, the transformation from equiaxed dendrites to columnar dendrites was observed in the weld metal. Epitaxial growth and delta ferrites were found around the fusion line between the Super 304H and the weld metal.

The Characteristics of Weld Metal Zone Welded with Various Filler Metals

2013 ◽  
Vol 690-693 ◽  
pp. 2673-2677
Author(s):  
Kyung Man Moon ◽  
Mun Jin Nam ◽  
Yeon Chang Lee ◽  
Yun Hae Kim ◽  
Jae Hyun Jeong
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Weld Metal ◽  
Post Weld Heat Treatment ◽  
Fuel Oil ◽  
Corrosion Properties ◽  
Repair Welding ◽  
Piston Crown ◽  
Filler Metals ◽  
Weld Heat

Recently, the fuel oil of diesel engines of marine ships is being changed to heavy oil of low quality as the oil price is getting higher and higher. Therefore, the wear and corrosion in all parts of the engine, such as cylinder liner, piston crown, and spindle and seat ring of exhaust valves has predominantly increased. Thus, the repair welding of the piston crown is a unique method to prolong its life in a economical point of view. In this case, filler metals with a high corrosion and wear resistance are mainly being used for repair welding. However, the piston crown on the ships job site is often actually being welded with mild filler metals. Therefore, in this study, mild filler metals, such as E4301, E431316, and E4316, were welded to the SS401 steel as the base metal, and the corrosion properties of their weld metals with and without post weld heat treatment were investigated with some electrochemical methods in 0.1% H2SO4 solution. The weld metal welded with E4301 filler metal exhibited the best corrosion resistance among the filler metals in the case of no heat treatment, however, its resistance was considerably decreased due to the post weld heat treatment (annealing:625°C, 2hr). In particular, the weld metal of E4316 exhibited relatively a good corrosion resistance by the post weld heat treatment.

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.

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.

Effect of Post Weld Heat Treatment on Weld Hardness Quality of P91 Welded Pipes

2015 ◽  
Vol 799-800 ◽  
pp. 377-381
Author(s):  
Mohd Amin Abd Majid ◽  
Muhammad Sarwar
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Residual Stresses ◽  
Weld Metal ◽  
Welded Joint ◽  
Post Weld Heat Treatment ◽  
Bead Geometry ◽  
Construction Sites ◽  
Weld Heat

Quality of a weld produced is generally evaluated by different parameters such as weld size, bead geometry, deposition rate, hardness and strength. A common problem that has been faced at the construction sites is to obtain a good welded joint having the required strength with minimal detrimental residual stresses to avoid any premature cracking due to high variation of hardness. In order to address this issue and to attain good weld quality, this study has been made to comprehend the effect of the post weld heat treatment on P91 material welds produced by TIG welding. Findings from the studies indicate that the PWHT has significant influence on the weld hardness of Alloy Steel-A335 P91 pipes. It is eminent that during cooling, after welding of P91, quenched martensite was formed in the HAZ that results in an increased hardness to an undesirable level of more than 250HB. PWHT at temperature of 760°C for 2 hours has good influence on mechanical properties as the hardness decreases and turns out to be uniformly distributed. If the PWHT is correctly carried out, the hardness of parent metals, heat affected zones and weld metal can be brought into the required limits to avoid any premature cracking due to high variation of hardness.

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