Effects of hybrid welding parameters on the toughness of weld metal in ship structural steel

2007 ◽  
Author(s):  
Seung-Gab Hong ◽  
Jong-Bong Lee
Keyword(s):  
Weld Metal ◽  
Structural Steel ◽  
Welding Parameters ◽  
Hybrid Welding

scholarly journals Influence of the Heat Input on the Dendritic Solidification Structure and the Mechanical Properties of 2.25Cr-1Mo-0.25V Submerged-Arc Weld Metal

2021 ◽  
Author(s):  
Hannah Schönmaier ◽  
Ronny Krein ◽  
Martin Schmitz-Niederau ◽  
Ronald Schnitzer
Keyword(s):  
Mechanical Properties ◽  
Weld Metal ◽  
Heat Input ◽  
Stress Rupture ◽  
Pressure Vessels ◽  
Rupture Time ◽  
Solidification Structure ◽  
Welding Parameters ◽  
Austenite Grain Size ◽  
Submerged Arc

AbstractThe alloy 2.25Cr-1Mo-0.25V is commonly used for heavy wall pressure vessels in the petrochemical industry, such as hydrogen reactors. As these reactors are operated at elevated temperatures and high pressures, the 2.25Cr-1Mo-0.25V welding consumables require a beneficial combination of strength and toughness as well as enhanced creep properties. The mechanical properties are known to be influenced by several welding parameters. This study deals with the influence of the heat input during submerged-arc welding (SAW) on the solidification structure and mechanical properties of 2.25Cr-1Mo-0.25V multilayer metal. The heat input was found to increase the primary and secondary dendrite spacing as well as the bainitic and prior austenite grain size of the weld metal. Furthermore, it was determined that a higher heat input during SAW causes an increase in the stress rupture time and a decrease in Charpy impact energy. This is assumed to be linked to a lower number of weld layers, and therefore, a decreased amount of fine grained reheated zone if the multilayer weld metal is fabricated with higher heat input. In contrast to the stress rupture time and the toughness, the weld metal’s strength, ductility and macro-hardness remain nearly unaffected by changes of the heat input.

scholarly journals GMA-laser Hybrid Welding of High-strength Fine-grain Structural Steel with an Inductive Preheating

2014 ◽  
Vol 56 ◽  
pp. 637-645 ◽  
Author(s):  
Rabi Lahdo ◽  
Oliver Seffer ◽  
André Springer ◽  
Stefan Kaierle ◽  
Ludger Overmeyer
Keyword(s):  
Structural Steel ◽  
High Strength ◽  
Hybrid Welding ◽  
Fine Grain ◽  
Laser Hybrid Welding ◽  
Laser Hybrid

The Influence of Welding Parameters on Heat Transfer Efficiency of Hybrid Pulsed Nd: YAG/GTAW Welding

2015 ◽  
Vol 1088 ◽  
pp. 807-813
Author(s):  
Miao Xia Xie ◽  
Lin Jie Zhang
Keyword(s):  
Heat Transfer ◽  
Nd:Yag Laser ◽  
Welding Process ◽  
Transfer Efficiency ◽  
304 Stainless Steel ◽  
Welding Parameters ◽  
Hybrid Welding ◽  
Pulsed Nd:Yag Laser ◽  
Heat Transfer Efficiency ◽  
Cross Section Area

In this work, effects of major welding parameters, such as laser power, defocus distance of laser beam, inter-heat sources distance and welding speed, on weld geometry were investigated for pulsed Nd:YAG laser/GTAW hybrid welding of 304 stainless steel. Heat transfer efficiency of pulsed Nd:YAG laser/GTAW hybrid welding process was quantitativly analyzed based on rosenthal equation. Furthermore, melting efficiency was determined from the measured welding seams cross section area.

A Predictive Electrochemical Model for Weld Metal Hydrogen Pickup in Underwater Wet Welds

1998 ◽  
Vol 120 (4) ◽  
pp. 243-248 ◽  
Author(s):  
R. C. de Medeiros ◽  
S. Liu
Keyword(s):  
Weld Metal ◽  
Hydrogen Content ◽  
Ferric Oxide ◽  
Welding Parameters ◽  
Oxide Content ◽  
Metal Interface ◽  
Feed System ◽  
Diffusible Hydrogen ◽  
Hydrogen Pickup ◽  
Electrochemical Model

Weld metal hydrogen pickup in underwater wet welding is severe due to the presence and dissociation of water surrounding the welding arc. This undesirable behavior can be minimized, however, with the use of oxidizing-type electrodes. The purpose of this investigation has been placed on the fundamental understanding of the effect of hydrogen pickup by the slag on the weld metal diffusible hydrogen content in direct current, shielded metal arc welding (SMAW) for both electrode-positive polarity (DCEP), and electrode-negative polarity (DCEN). To accomplish this purpose, 20 experimental oxidizing electrodes containing systematic ferric oxide (Fe2O3) additions, ranging from 0 to 70 wt. percent, to the flux coating were investigated. The mole fraction ratio of CaO/SiO2 in the fluxes ranged from 0.05 to 0.35, independent of the ferric oxide additions. Underwater, bead-on-plate welds were deposited on ASTM A36 steel coupons at 0.27 m (city) water depth using a gravity feed system. Welding parameters were held constant throughout the experiments. Weld metal diffusible hydrogen content was determined using the mercury displacement method according to current AWS standard. To correlate weld metal hydrogen content with slag chemistry, the slag hydrogen contents were also determined. The measured diffusible hydrogen contents showed that Fe2O3 was effective in reducing weld metal hydrogen content. Higher hydrogen values were always related to lower Fe2O3 contents initially present in the flux, for instance, 71 mL/100g (DCEP − 0 wt. percent Fe2O3) as compared to 31 mL/100g (DCEP − 36 wt. percent Fe2O3). Amazingly, diffusible hydrogen as low as 13 mL/100g was obtained with the use of DCEN polarity along with 53 wt. percent Fe2O3 in the flux coating. X-ray diffraction (XRD) conducted on different slags showed that the lower diffusible hydrogen values were always associated with the presence of fayalite (2FeO·SiO2). Complementing XRD analysis, Mo¨ssbauer spectroscopy analyses carried out on different slags showed that all ferric (Fe3+) oxide initially present in the slags had transformed to ferrous oxide (FeO), free or combined. Chemical analyses showed that weld metal hydrogen pickup was strongly dependent on the solubility of water in the slag systems. The total and diffusible hydrogen content in the weld metal increased monotonically with increasing slag hydrogen content. Finally, variations in weld metal hydrogen as well as slag hydrogen content with both polarity and iron oxide content in the slag were successfully predicted using an electrochemical model that describes the slag/metal interface equilibrium. In this investigation, the slag/metal interface has been identified as responsible in controlling the weld metal hydrogen pickup. The model assumed that hydrogen was present in the slag as (OH)− ions and that FeO displayed ideal solution behavior.

Recommendations for Submerged Arc Spiral Welding With Optimized CTOD Properties

2018 ◽  
Author(s):  
Martin Liebeherr ◽  
Özlem E. Güngör ◽  
Nuria Sanchez ◽  
Hervé Luccioni ◽  
Nenad Ilic
Keyword(s):  
Weld Metal ◽  
Base Material ◽  
Welding Process ◽  
Experimental Program ◽  
Welding Parameters ◽  
Pipe Production ◽  
Filler Wire ◽  
Crack Tip Opening Displacement ◽  
Wide Range ◽  
Submerged Arc

Many pipe mills may not be familiar with a Crack Tip Opening Displacement (CTOD) requirement on the pipe seam weld, nor will they find easily relevant information in open literature. Influencing — and certainly not independent — factors are: welding parameters, base material and consumable selection. Out of these, the welding parameters such as heat input and cooling rate cannot be varied over a wide range during the pipe production, which means that the leverage is rather limited at the given welding process. The properties of the heat affected zone will be mainly affected by the base material, while the properties of the weld metal will be affected by both, base material and filler wire selection. In particular with respect to the weld metal properties it will be difficult to obtain general quantitative information. For example, a welding consumable supplier will readily provide the properties of the filler wires but would be unable to predict the changes caused by the dilution from any base material in the weld pool and specific welding procedures that may have been used. To support the pipe mills in the selection of the consumables for submerged arc welding, an experimental program was launched with the aim to provide recommendations on how to optimize CTOD toughness of the spiral weld seam. For this, a large number of welds were produced on 20 mm thick X70 coil samples, with eight different filler wire combinations, using a 2-wire (tandem) set-up for both the inside and outside weld. Welding parameters were kept constant. The welding program was applied to two different X70 steels to determine a potential influence of the micro-alloying elements, particularly Nb. The results show clearly that a careful consumable selection is required for obtaining acceptable CTOD toughness in the weld metal. Ni-Mo and Ti-B additions to the weld metal are found to be beneficial with both steel concepts. Mo addition alone both to the ID and OD welds was clearly not a suitable selection.

Influence of Extra Coarse Grains on the Creep Properties of 9 Percent CrMoV (P91) Steel Weldment

2004 ◽  
Vol 126 (1) ◽  
pp. 87-94 ◽  
Author(s):  
Rui Wu ◽  
Rolf Sandstro¨m ◽  
Facredin Seitisleam
Keyword(s):  
Weld Metal ◽  
Strain Rate ◽  
Creep Strain ◽  
Coarse Grained ◽  
Welding Parameters ◽  
Parent Metal ◽  
Austenite Grain Size ◽  
P91 Steel ◽  
Coarse Grains ◽  
The Cross

With modern welding methods, satisfactory microstructures in 9%CrMoV (P91) steel can be obtained with a modest variation in hardness and prior austenite grain size. However, there is always a risk that significant deviations in the properties can be obtained, if the welding parameters are not optimized. In the present paper the role of extra coarse grains in the heat affected zone (HAZ) has been studied. Creep tests were carried out at 600°C for parent metal, weld metal, cross weld, simulated extra coarse grained HAZ, and simulated intercritical HAZ of a 9%CrMoV (P91) steel. The parent metal, the cross welds, the weld metal, and the simulated intercritical HAZ had about the same rupture strength except at long rupture times, where the values for the cross welds were considerably lower. In the cross welds, rupture took place in the intercritical HAZ at longer times (Type IV cracking). The simulated extra coarse grains gave considerably longer rupture times, lower strain rate and lower creep ductility than the parent metal and the weld metal. The creep strain behavior was successfully analyzed using the Omega model where the log creep strain rate is linear in the creep strain.

Compositional Aspects of Cellulosic Electrodes Used for Welding Pipelines

2008 ◽  
Author(s):  
Frank J. Barbaro ◽  
Valerie M. Linton ◽  
Erwin Gamboa ◽  
Leigh Fletcher
Keyword(s):  
Weld Metal ◽  
User Involvement ◽  
Charpy Impact ◽  
Carbon Equivalent ◽  
Welding Parameters ◽  
Line Pipe ◽  
User Input ◽  
Welding Arc ◽  
Simulated Field ◽  
And Performance

The mechanical properties and compositional limits of line pipe for all major pipeline projects are subject to stringent project specific specifications and have substantial user input. The standards for welding electrodes do not have the same level of user involvement and permit significant latitude in terms of alloy design despite the fact that it is known the original electrode design can be markedly altered by elemental transfer as a result of changes in welding parameters and also the condition of the electrodes prior to welding. Several commercially available E8010 consumables have been evaluated under simulated field welding conditions. In addition, the influence of welding arc length and electrode conditioning were investigated. Significant variations in microstructure, hardness and Charpy impact toughness were noted and appear to be primarily related to the final chemical composition of the deposited weld metal. The weld metal carbon equivalent values ranged from 0.20 to 0.42 and all consumables contained additions of Ti and B in the flux coating which resulted in significant levels of B in the final deposited weld metal. It is recommended that the appropriate standards relating to the production and performance of cellulosic consumables be addressed to ensure complete disclosure of consumable formulations to the end user.

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