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.

Effect of Mg Content on the Microstructure and Toughness of Heat-Affected Zone of Steel Plate after High Heat Input Welding

2016 ◽  
Vol 47 (7) ◽  
pp. 3354-3364 ◽  
Author(s):  
Long-Yun Xu ◽  
Jian Yang ◽  
Rui-Zhi Wang ◽  
Yu-Nan Wang ◽  
Wan-Lin Wang
Keyword(s):  
Heat Affected Zone ◽  
Heat Input ◽  
Steel Plate ◽  
High Heat ◽  
High Heat Input ◽  
Mg Content

scholarly journals Influence of Al Content on the Inclusion-Microstructure Relationship in the Heat-Affected Zone of a Steel Plate with Mg Deoxidation after High-Heat-Input Welding

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1027 ◽  
Author(s):  
Longyun Xu ◽  
Jian Yang ◽  
Ruizhi Wang
Keyword(s):  
Heat Affected Zone ◽  
Heat Input ◽  
Steel Plate ◽  
High Heat ◽  
Al Content ◽  
High Heat Input ◽  
Al Addition ◽  
Inclusions In Steel ◽  
Haz Toughness ◽  
Better Than

The effects of Al content on inclusions, microstructures, and heat-affected zone (HAZ) toughness in a steel plate with Mg deoxidation have been investigated by using simulated high-heat-input welding and an automated feature system. The studies indicated that the main kind of oxysulfide complex inclusions in two steels without and with Al addition were both MgO-MnS. The number densities and mean sizes of inclusions were 96.65 mm−2 and 3.47 μm, 95.03 mm−2 and 2.03 μm, respectively. The morphologies of MgO-MnS complex inclusions in steel were changed obviously with the addition of Al. When containing 0.001 wt.% Al, they consisted of a central single MgO particle and outside, the MnS phase. When containing 0.020 wt.% Al, they comprised several small MgO particles entrapped by the MnS phase. Because the former could nucleate intragranular acicular ferrites (IAFs) and the latter was non-nucleant, the main intragranular microstructures in HAZs were ductile IAFs and brittle ferrite side plates (FSPs), respectively. Therefore, HAZ toughness of the steel plate without Al addition after high-heat-input welding of 400 kJ/cm was significantly better than that of the steel plate with Al addition.

Improvement of HAZ Toughness of Steel Plate for High Heat Input Welding by Inclusion Control with Mg Deoxidation

2015 ◽  
Vol 86 (6) ◽  
pp. 619-625 ◽  
Author(s):  
Jian Yang ◽  
Longyun Xu ◽  
Kai Zhu ◽  
Ruizhi Wang ◽  
Lejun Zhou ◽  
...  
Keyword(s):  
Heat Input ◽  
Steel Plate ◽  
High Heat ◽  
High Heat Input ◽  
Inclusion Control ◽  
Haz Toughness

scholarly journals Improvement of Heat-Affected Zone Toughness of Steel Plates for High Heat Input Welding by Inclusion Control with Ca Deoxidation

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 946 ◽  
Author(s):  
Ruizhi Wang ◽  
Jian Yang ◽  
Longyun Xu
Keyword(s):  
Heat Affected Zone ◽  
Heat Input ◽  
High Heat ◽  
Steel Plates ◽  
Number Density ◽  
High Heat Input ◽  
Intragranular Acicular Ferrite ◽  
Average Size ◽  
Inclusion Control ◽  
Haz Toughness

The characteristics of inclusions and microstructure in heat-affected zones (HAZs) of steel plates with Ca deoxidation after high heat input welding of 400 kJ·cm−1 were investigated through simulated welding experiments and inclusions automatic analyzer systems. Typical inclusions in HAZs of steels containing 11 ppm and 27 ppm Ca were recognized as complex inclusions with the size in the range of 1~3 μm. They consisted of central Al2O3 and peripheral CaS + MnS with TiN distributing at the edge (Al2O3 + CaS + MnS + TiN). With increasing Ca content in steel, the average size of inclusions decreased from 2.23 to 1.46 μm, and the number density increased steadily from 33.7 to 45.0 mm−2. Al2O3 + CaS + MnS + TiN complex inclusions were potent to induce the formation of intragranular acicular ferrite (IAF). Therefore, the HAZ toughness of steel plates after high heat input welding was improved significantly by utilizing oxide metallurgy technology with Ca deoxidation.

Microstructure and Properties of Grade 700MPa Pressure Vessel Steel with Large Heat Input Welding

2012 ◽  
Vol 182-183 ◽  
pp. 1537-1540
Author(s):  
Qing Feng Ding ◽  
Tian Sheng Wang ◽  
Wen Yan Liu ◽  
Xian Jun Wang ◽  
Wen Bin Liu ◽  
...  
Keyword(s):  
Impact Energy ◽  
Heat Input ◽  
High Heat ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Microstructure And Properties ◽  
Technical Requirements ◽  
High Heat Input ◽  
Large Heat ◽  
Haz Toughness

The microstructure and properties of grade 700MPa steel with large heat input welding and its heat affected zone (HAZ) were investigated by use of the metallography, scanning electron microscopy, mechanical testing and welding thermal simulation. The results showed that the mechanical properties of the steel meet the technical requirements, namely the yield strength ReL≥570 MPa, the tensile strength 685MPa≤Rm≤830MPa, the elongation A≥17%, the -20°C impact energy KV2≥54J and the -20°C impact energy of HAZ≥47J. The steel also had good match between strength, toughness and anti-high heat input welding, the microstructure was tempered sorbite with small dispersed composite inclusions, which promoted the formation of acicular ferrite and were beneficial to the improvement of HAZ toughness.

scholarly journals Higher-Strength Steels Specially Processed for High Heat Input Welding

1985 ◽  
Vol 1 (04) ◽  
pp. 222-237
Author(s):  
I. L. Stern ◽  
M. Wheatcroft ◽  
D. Y. Ku
Keyword(s):  
Heat Affected Zone ◽  
Heat Input ◽  
Large Scale ◽  
Welding Process ◽  
High Heat ◽  
Coast Guard ◽  
Steel Plates ◽  
Small Scale ◽  
Bulge Testing ◽  
High Heat Input

ABS Grade EH36 steel plates, specially formulated and produced with advanced metallurgical techniques, are shown to have a significantly greater resistance to weld heat-affected zone (HAZ) degradation that conventional EH36 steel. Welds made in these steels with the electroslag welding process at high heat input rates retained adequate toughness in the heat-affected zone at --4°F (-20°C); similar welds in conventional EH36 steel plate exhibit excessive HAZ toughness loss. This effect was confirmed on the basis of small-scale Charpy V-notch and large-scale explosion bulge testing. In view of their superior resistance to HAZ degradation, the steels should also be useful for applications where HAZ degradation is of particular concern, such as for American Bureau of Shipping (ABS), U.S. Coast Guard, and International Maritime Organization (IMO) weld requirements for liquefied gas carriers.

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