scholarly journals In-situ observation on the influences of Ti on phase transformation of weld metal processed by high-heat input welding

2020 ◽  
Vol 12 (9) ◽  
pp. 168781402096228
Author(s):  
Song Fengyu ◽  
Yao Lingzhen ◽  
Li Yanmei
Keyword(s):  
Phase Transformation ◽  
Weld Metal ◽  
Heat Input ◽  
High Heat ◽  
Transformation Process ◽  
In Situ Observation ◽  
High Heat Input ◽  
Bainite Microstructure ◽  
Ti Content

The in-situ observation of the phase transformation processes of weld metal during high-heat input welding were carried out by a high temperature laser confocal microscope. The influences of Ti content on the phase transformation process were investigated. It was found that the Ti inclusions could act as the nucleation sites for α→γ transformation during the heating stage of welding thermo cycle and inhibit the growth of austenite grains. The number of inclusions was increased with increasing Ti content. During the cooling stage of welding thermo cycle, the inclusions could induce the nucleation of acicular ferrites when the Ti content was below 0.078%. With increasing Ti content, more acicular ferrites collided with each other and restricted their further growth. When the Ti content was increased up to 0.115%, a proportion of Ti atoms were dissolved in the matrix, which increased the hardenability and thus generated the lath bainite microstructure instead of acicular ferrite.

In-situ observation of the fusion zone under different high heat input for hot-rolled ship plate steel with 0.012yttrium

2019 ◽  
Vol 6 (12) ◽  
pp. 126517
Author(s):  
Qi-Hang Pang ◽  
Huan Qi ◽  
Juan Cui ◽  
Wei-Juan Li ◽  
Jing Guo ◽  
...  
Keyword(s):  
Fusion Zone ◽  
Heat Input ◽  
High Heat ◽  
In Situ Observation ◽  
Plate Steel ◽  
High Heat Input ◽  
Hot Rolled

Effects of oxygen content on microstructure and impact toughness of high heat input flux-cored wire weld metals

2018 ◽  
Vol 115 (4) ◽  
pp. 410
Author(s):  
Fengyu Song ◽  
Yanmei Li ◽  
Ping Wang ◽  
Fuxian Zhu
Keyword(s):  
Grain Size ◽  
Impact Toughness ◽  
Weld Metal ◽  
Oxygen Content ◽  
Heat Input ◽  
High Heat ◽  
Cored Wire ◽  
Weld Metals ◽  
High Heat Input ◽  
The Impact

Three weld metals with different oxygen contents were developed. The influence of oxygen contents on the microstructure and impact toughness of weld metal was investigated through high heat input welding tests. The results showed that a large number of fine inclusions were formed and distributed randomly in the weld metal with oxygen content of 500 ppm under the heat input condition of 341 kJ/cm. Substantial cross interlocked acicular ferritic grains were induced to generate in the vicinity of the inclusions, primarily leading to the high impact toughness at low temperature for the weld metal. With the increase of oxygen content, the number of fine inclusions distributed in the weld metal increased and the grain size of intragranular acicular ferrites decreased, which enhanced the impact toughness of the weld metal. Nevertheless, a further increase of oxygen content would contribute to a great diminution of the austenitic grain size. Following that the fraction of grain boundary and the start temperature of transformation increased, which facilitated the abundant formation of pro-eutectoid ferrites and resulted in a deteriorative impact toughness of the weld metal.

High Heat Input Welding of 12Cr-6Ni-2.5Mo Supermartensitic Stainless Steel

2003 ◽  
Author(s):  
Ragnhild Aune ◽  
Hans Fostervoll ◽  
Odd Magne Akselsen
Keyword(s):  
Weld Metal ◽  
Stainless Steels ◽  
Heat Affected Zone ◽  
Heat Input ◽  
High Heat ◽  
Maximum Heat ◽  
Final Microstructure ◽  
Girth Welding ◽  
High Heat Input ◽  
Longitudinal Seam

In conventional welding of 13% Cr supermartensitic stainless steels, the normal microstructure that forms on cooling is martensite. Although high heat input tends to give a certain coarsening of the final microstructure, the eventual accompanying loss in toughness is not known. The present study was initiated to examine the effect of heat input on weld metal and heat affected zone mechanical properties of a 12Cr-6Ni-2.5Mo grade. The results obtained showed that the notch toughness is low (25 J) and independent of heat input for the weld metal, while it is reduced with increasing heat input for fusion line and the heat affected zone locations. Subsequent post weld heat treatment gave a substantial increase in toughness for all notch locations. Based on these results, indications are that a specified maximum heat input is not applicable in welding of supermartensitic stainless steels, allowing more production efficient techniques to be used, both in longitudinal seam and girth welding.

scholarly journals Mechanism of Improving Heat-Affected Zone Toughness of Steel Plate with Mg Deoxidation after High-Heat-Input Welding

Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 162 ◽  
Author(s):  
Longyun Xu ◽  
Jian Yang ◽  
Joohyun Park ◽  
Hideki Ono
Keyword(s):  
Heat Input ◽  
Steel Plate ◽  
High Heat ◽  
Steel Plates ◽  
In Situ Observation ◽  
Austenite Grain ◽  
Micron Size ◽  
High Heat Input ◽  
Mg Content ◽  
Haz Toughness

In the present study, the mechanism of improving HAZ toughness of steel plate with Mg deoxidation after the simulated welding with the heat input of 400 kJ/cm was investigated through in situ observation, characterization with SEM-EDS and TEM-EDS, and thermodynamic calculation. It was found that intragranular acicular ferrite (IAF) and polygonal ferrite (PF) contributed to the improvements of HAZ toughness in steels with Mg deoxidation. With the increase of Mg content in steel, the oxide in micron size inclusion was firstly changed to MgO-Ti2O3, then to MgO with the further increase of Mg content in steel. The formation of nanoscale TiN particles was promoted more obviously with the higher Mg content in the steel. The growth rates of austenite grains at the high-temperature stage (1400~1250 °C) during the HAZ thermal cycle of steels with conventional Al deoxidation and Mg deoxidation containing 0.0027 and 0.0099 wt% Mg were 10.55, 0.89, 0.01 μm/s, respectively. It was indicated that nanoscale TiN particles formed in steel with Mg deoxidation were effective to inhibit the growth of austenite grain. The excellent HAZ toughness of steel plates after welding with a heat input of 400 kJ/cm could be obtained by control of the Mg content in steel to selectively promote the formation of IAF or retard the growth of austenite grain.

Improvement of Weld Metal Toughness in High Heat Input Electro-Slag Welding of Low Carbon Steel

2009 ◽  
Vol 53 (3-4) ◽  
pp. R57-R63 ◽  
Author(s):  
Yasushi Kitani ◽  
Rinsei Ikeda ◽  
Moriaki Ono ◽  
Kenji Ikeuchi
Keyword(s):  
Carbon Steel ◽  
Weld Metal ◽  
Heat Input ◽  
Low Carbon Steel ◽  
High Heat ◽  
Low Carbon ◽  
High Heat Input

scholarly journals Microstructural evolution of 2.25Cr-1Mo-0.25V submerged-arc weld metal

2019 ◽  
Vol 64 (2) ◽  
pp. 379-393
Author(s):  
Hannah Schönmaier ◽  
Fred Grimm ◽  
Ronny Krein ◽  
Katharina Kirchheimer ◽  
Ronald Schnitzer
Keyword(s):  
Phase Transformation ◽  
High Temperature ◽  
Weld Metal ◽  
Manganese Oxides ◽  
Laser Scanning ◽  
Pressure Vessels ◽  
In Situ Observation ◽  
Final Microstructure ◽  
Austenite Grains

AbstractHeat-resistant V-modified 2.25Cr-1Mo-0.25V-weld metal is commonly used in petrochemical industry for heavy wall pressure vessels in high-temperature hydrogen service. In order to improve the reactor efficiency, the weldments have to endure even higher temperatures and pressures. Acicular ferrite (AF) is often regarded as the optimum microstructure due to its good combination of strength and toughness. As few literature about the evolution of microstructure and the final microstructure constituents of 2.25Cr-1Mo-0.25V weld metal is available, the current paper intends to provide comprehensive information by means of microscopy, crystallographic examination via electron backscatter diffraction and in situ observation of the austenite to ferrite phase transformation via high-temperature laser scanning confocal microscopy (HT-LSCM). The investigated weld metal exhibits a high density of complex aluminium-silicon-manganese oxides with a spherical shape and large prior austenite grains, which in combination is beneficial for intragranular nucleation of AF. Nonetheless, the examination of the transformed final microstructure was not sufficient to make an unambiguous statement about the presence of AF within the 2.25Cr-1Mo-0.25V weld metal. Via in-situ HT-LSCM of the phase transformation, intragranular nucleation of AF at non-metallic inclusions within the austenite grains was detected, which confirms that even though the microstructure of 2.25Cr-1Mo-0.25V weld metal is mainly bainitic, small amounts of AF are present.

Fatigue crack growth rates on the weld metal of high heat input submerged arc welding

2019 ◽  
Vol 119 ◽  
pp. 43-51 ◽  
Author(s):  
Luiz Henrique Soares Barbosa ◽  
Paulo José Modenesi ◽  
Leonardo Barbosa Godefroid ◽  
Ariel Rodriguez Arias
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Weld Metal ◽  
Heat Input ◽  
Arc Welding ◽  
High Heat ◽  
Submerged Arc Welding ◽  
High Heat Input ◽  
Crack Growth Rates ◽  
Submerged Arc
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