Effect of Mg addition on formation of intragranular acicular ferrite in heat-affected zone of steel plate after high-heat-input welding

2018 ◽  
Vol 25 (4) ◽  
pp. 433-441 ◽  
Author(s):  
Long-yun Xu ◽  
Jian Yang ◽  
Rui-zhi Wang ◽  
Wan-lin Wang ◽  
Yu-nan Wang
2016 ◽  
Vol 47 (7) ◽  
pp. 3354-3364 ◽  
Author(s):  
Long-Yun Xu ◽  
Jian Yang ◽  
Rui-Zhi Wang ◽  
Yu-Nan Wang ◽  
Wan-Lin Wang

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1027 ◽  
Author(s):  
Longyun Xu ◽  
Jian Yang ◽  
Ruizhi Wang

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.


Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 946 ◽  
Author(s):  
Ruizhi Wang ◽  
Jian Yang ◽  
Longyun Xu

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.


2015 ◽  
Vol 55 (9) ◽  
pp. 2018-2026 ◽  
Author(s):  
Takako Yamashita ◽  
Junji Shimamura ◽  
Kenji Oi ◽  
Masayasu Nagoshi ◽  
Katsunari Oikawa ◽  
...  

Author(s):  
Ragnhild Aune ◽  
Hans Fostervoll ◽  
Odd Magne Akselsen

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.


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