scholarly journals Metallurgical Characterization of Welded Joint of Nanostructured Bainite: Regeneration Technique versus Post Welding Heat Treatment

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4841
Author(s):  
Aleksandra Królicka ◽  
Krzysztof Radwański ◽  
Aleksandra Janik ◽  
Paweł Kustroń ◽  
Andrzej Ambroziak
Keyword(s):  
Heat Treatment ◽  
Welded Joint ◽  
Construction Material ◽  
Weld Zone ◽  
Base Material ◽  
Welding Process ◽  
Solidification Structure ◽  
Hardness Distribution ◽  
Diffusion Type

One of the main limitations in application of nanostructured carbide-free bainite as a construction material is the difficulty of joining. This research presents a structural characterization of welded joints of medium carbon 55Si7 grade steel after the welding process with a regeneration technique as well as post welding heat treatment (PWHT). The hardness distribution of the welded joint with regeneration exhibit an overall decrease in hardness when compared to the base material and a significant decrease in hardness was observed in the heat-affected zone (HAZ). Unfavorable hardness distribution was caused by the presence of diffusion-type transformations products (pearlite) in the HAZ and bainite degradation processes. On the other hand, welding with the PWHT promotes the achievement of a comparable level of hardness and structure as in the base material. However, a slight decrease in hardness was observed in the weld zone due to the micro-segregation of the chemical composition caused by the indissoluble solidification structure. Based on the structural analysis, it was found that steel with relatively low hardenability (55Si7) should be welded using PWHT rather than a regeneration technique.

Cause Analysis and Preventive Measures against Cracks in 15Cr1Mo1V Steel Welded Joint in Service

2017 ◽  
Vol 863 ◽  
pp. 328-333
Author(s):  
Wei Shi ◽  
Yi Shi Lv ◽  
Zhong Bing Chen ◽  
Ling Hui Meng ◽  
Li Jun Zhang ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Stress Concentration ◽  
Welded Joint ◽  
Welding Process ◽  
Postweld Heat Treatment ◽  
Additional Stress ◽  
Heat Affect Zone ◽  
Crack Morphology ◽  
Deformation Ability ◽  
Postweld Heat

Characteristics and forming causes of the cracks in welded joint of 15Cr1Mo1V steel serviced 70000h are investigated by mechanical and chemical testing and crack morphology observation. Results show that the cracks initiate from welded metal or coarse grain heat affect zone (CGHAZ) near fusion line, and there are three kinds of defects observed in the crack region, which are macrocracks, microcracks and voids. According to the forming position, process and morphology of the cracks, it is estimated that the cracks are a kind of stress relief crack (SRC). The main reasons of the cracking are because of residual stress caused by improper temperature field during post welding heat treatment, strong stress concentration caused by welding structure, additional stress caused by abnormal hangers & supports and decreased ductility of welded joint in service. The SRC in welded joint can be avoided through optimizing the welding process and postweld heat treatment(PWHT) process to ensure enough critical ductility deformation ability εc and avoiding and reducing stress concentration and additional stress to decrease ductility deformation εP of welded joint which make εc>εp consistently.

Characterization of Surface Defects Associated with Flash Butt-Welded Pearlitic Rails and their Contribution to Overload and Fatigue Failures

2009 ◽  
Vol 83-86 ◽  
pp. 1262-1269 ◽  
Author(s):  
Mostafa Mousavizade ◽  
Hassan Farhangi
Keyword(s):  
Surface Defects ◽  
Weld Zone ◽  
Welding Process ◽  
Electrical Heating ◽  
Main Concern ◽  
Zone Formation ◽  
Butt Welding ◽  
Fatigue Failures

Generally about 80 percent of railway tracks are welded by flash-butt welding that consists of electrical heating and hydraulic forging. Fracture of rails specially weld zone fractures are of main concern because of potential risk of a catastrophic derailment. In this paper, surface defects associated with flash butt welding process are examined. Metallographic and fractographic studies show various defects can be formed at the surface of weld zone. Formation mechanism of these defects and their contribution to the observed fatigue and overload weld failures are discussed. Fracture mechanics is also utilized to clarify the role of these defects in fatigue and overload failures.

scholarly journals Induction Weld Seam Characterization of Continuously Roll Formed TRIP690 Tubes

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 425
Author(s):  
Alexander Bardelcik ◽  
Bharathwaj Thirumalai Ananthapillai
Keyword(s):  
Weld Seam ◽  
Welding Process ◽  
Tension Test ◽  
Hardness Distribution ◽  
Roll Force ◽  
Ring Specimen ◽  
Excellent Performance ◽  
Peak Loads ◽  
Induction Frequency

The weld seam characteristics of continuously roll formed and induction seam welded TRIP690 tubes were examined in this work. These tube are subsequently used in automotive hydroforming applications, where the weld seam characteristics are critical. The induction seam welds are created through a solid-state welding process and it was shown that by increasing the induction frequency by 26%, the weld seam width within the heat affected zone (HAZ) reduced due to a plateau in the hardness distribution which was a result of a delay in the transformation of martensite. 2D hardness distribution contours were also created to show that some of the weld conditions examined in this work resulted in a strong asymmetric hardness distribution throughout the weld, which may be undesirable from a performance perspective. An increase in the pressure roll force was also examined and revealed that a wider total weld seam width was produced likely due to an increase in temperature which resulted in more austenitization of the sheet edge prior to welding. The ring hoop tension test (RHTT) was applied to the tube sections created in this work. A Tensile and Notch style ring specimen were tested and revealed excellent performance for these welds due to high peak loads (~17.2 kN) for the Notch specimens (force deformation within weld) and lower peak loads (~15.2 kN) for the Tensile specimens for which fracture occurred in the base metal.

Preparation and Characterization of Golden-Colored Pigments Based on Silver Coated with Metal Oxides

2008 ◽  
Vol 47-50 ◽  
pp. 1462-1465
Author(s):  
Yuko Tateishi ◽  
Hisahiro Einaga ◽  
Yasutake Teraoka
Keyword(s):  
Heat Treatment ◽  
Silver Powder ◽  
Base Material ◽  
Treatment Temperature ◽  
Metal Species ◽  
Color Tone ◽  
Metallic Luster ◽  
Golden Color ◽  
Loading Amount

The present study aimed at the development of new artificial golden-colored pigments which are thermally stable up to 900 oC and can be used for coloring ceramics wares. Silver was used as a base material with bright metallic luster. Silver with the larger lamellar structure was indispensable to maintain the metallic luster, and it was successfully obtained by the heat-treatment of as-obtained silver powder at 200-400 oC in air and subsequently dry ball-milling at 300 rpm for 1 h. The surface of the lamellar-structured silver was coated with small particles of hydroxides, oxyhydroxides and oxides of Fe, Co, Ni, Ce and Pr. Appearance of golden color depended on the combination of metal species and heat-treatment temperature, and CeO2-coated silver gave golden color after calcination at 800 and 900 oC. The golden color of CeO2-coated silver could be controlled by the loading amount and particle size of CeO2 for color tone and relative area of naked surface of Ag for luster.

Mechanical Characterization of AA2024-T3 FSWed Butt Joints

2013 ◽  
Vol 753-755 ◽  
pp. 431-434 ◽  
Author(s):  
Pierpaolo Carlone ◽  
Gaetano S. Palazzo
Keyword(s):  
Mechanical Properties ◽  
Mechanical Characterization ◽  
Base Material ◽  
Welding Process ◽  
Butt Joints ◽  
Influence Of Process Parameters ◽  
Rotating Speed ◽  
Friction Stir ◽  
Process Heat

In recent years friction stir welding process has received a great deal of attention from the transport industry. During the process, heat generation and material stirring induce significant microstructural alteration in the base material, affecting the properties of the welded assembly. In this paper the influence of process parameters, namely rotating speed and welding speed, on mechanical properties of AA2024-T3 friction stir butt welds is experimentally investigated. An increase of the yield stress has been found decreasing the heat input, while an opposite variation was measured for the elongation.

Microstructure Characterization of AZ31B Mg Alloy Welds Processed by Nd:YAG Laser Welding

2017 ◽  
Vol 898 ◽  
pp. 1051-1055 ◽  
Author(s):  
Hong Tao Liu ◽  
Ruo Chao Wang ◽  
Qing Liu ◽  
Ji Xue Zhou ◽  
Yan Fei Chen ◽  
...  
Keyword(s):  
Laser Welding ◽  
Nd:Yag Laser ◽  
Energy Dispersive Spectrometer ◽  
Base Material ◽  
Welding Process ◽  
Microstructure Characterization ◽  
Columnar Grains ◽  
Equiaxed Grains ◽  
Laser Welding Process

The Nd:YAG laser welding process of AZ31B alloys was performed by using the six-axis robot in this work. The microstructure characterization of AZ31B auto-welded joints was studied by using scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The laser welding process resulted in the formation of equiaxed grains in the center of the fusion zone (FZ) and columnar grains near the FZ boundary, meanwhile some eutectic β-Mg17Al12 particles were observed in the microstructure. No clear heat affected zone (HAZ) was observed in the welded AZ31B joint. Furthermore, some pores were observed in the base material (BM) and FZ.

Influence of Welding Process on the Microstructure of Carbon Steel and Stainless Steel Heterogeneous Welded Joints

2016 ◽  
Vol 1138 ◽  
pp. 31-36
Author(s):  
Maria Cristina Dijmarescu ◽  
Dumitru Titi Cicic ◽  
Corneliu Rontescu ◽  
Gheorhe Solomon
Keyword(s):  
Chemical Composition ◽  
Carbon Steel ◽  
Structural Characterization ◽  
Base Material ◽  
Welding Process ◽  
Cored Wire ◽  
Base Materials ◽  
Flux Cored Arc Welding ◽  
Welded Seam

The reactions of the base material, during the welding process, consist in chemical composition, volume, structure and granulation changes. There are multiple problems which can occur by welding two steels with totally different chemical composition, i.e. carbon steel S235JR + AR and austenitic stainless X2CrNiMo17-12-2. The process used for making the heterogeneous joint was flux cored arc welding (FCAW), numerically coded 136. The paper presents the effects of welding through heat input, on the structural characterization of welded seam and heat affected zone. It also focuses on the structural characterization of the welded joint obtained using the flux cored wire T 23 12 L P C/M 1, and determining how the base materials participate at the formation of the welding joint.

Comparison of Mechanical and Microstructural Characteristics in Maraging 300 Steel Welded by PAW and GTAW Processes Submitted to Repair

2016 ◽  
Vol 1135 ◽  
pp. 255-264 ◽  
Author(s):  
Paulo Roberto Sakai ◽  
Deivid Ferreira da Silva ◽  
Sandro Lombardo ◽  
Antonio Jorge Abdalla
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Base Material ◽  
Welding Process ◽  
Repair Process ◽  
High Temperature Strength ◽  
Maraging Steels ◽  
Ultrahigh Strength ◽  
Ultrahigh Strength Steels ◽  
Welding Processes

Maraging steels are a special class of ultrahigh-strength steels which presents a combination of high mechanical strength, excellent toughness, high temperature strength and corrosion resistance. The joint of sheets/plates by welding processes are fundamental for aeronautical and industrial products in addition Brazil has been developing technologies in welding ultrahigh-strength steels such as AISI 4340ESR and SAE 300M steels for its domestic space launch program and has currently decided for the replacement of these steels by Maraging 300 steel in some projects. In this work, we studied the welding process of the Maraging 300 steel for two different routes: Tungsten Inert Gas (TIG or GTAW) and Plasma Arc Welding (PAW). Filler additions were used for both processes. Procedure after any welding demands non destructive testing and sometimes non approved defects considering the usage of the product require for welding repair. Verification of the effects of this operation was made through a simulation of a welding repair for both types of welding. Specimens were submitted to heat treatment consisting of a solution annealing and aging and their microstructures were examined. The microhardness measurements were made on samples with and without repair characterized the fusion and heat affected zones. Specimens were submitted to tensile testing and the fractured surfaces were examined by a scanning electron microscope. Results of microstructure exam revealed the presence of austenite (γ) in FZ (Fusion Zone). After the welding repair simulation, a new different colored zone appeared in the HAZ (Heat Affected Zone) for both processes due to reheating of the sheet provided by the repair process. In the HAZ near FZ an important grain growth due to the heating occurred. Also, close FZ that was submitted to new heating due to repair it was noted an apparent growing of grain size relative to original grain size. The microhardness measurements showed that there is a reduction in hardness in the FZ and the region immediately (fusion line) compared to base material values. After the aging heat treatment a recovery of hardness values took place in these regions but the values themselves remain smaller than the base material. It was observed an increase of values of the microhardness in dark regions in the HAZ provoked by a phenomenon of aging locally due to the dissipation of the heat of the welding process and posterior repair. After aging, those differences disappeared. It was observed that there was not a large difference between the yield and strength limits considering both processes of welding, as well as between both situations after repair. It could be seen that the rupture began in the region near FZ and followed in the direction of the weld bead. The analysis of the fracture surfaces showed that this happened by ductile way, forming dimples.

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.

Sign in / Sign up

Export Citation Format

Share Document