Effect of Titanium and Nitrogen on Toughness of Heat-Affected Zone of Steel Plate with Tensile Strength of 50kg/mm<SUP>2</SUP> in High Heat Input Welding

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.

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Microstructure and Fracture Characteristics of Heat‐Affected Zone in Shipbuilding Steel Plates with Mg Deoxidation after High Heat Input Welding

steel research international ◽

10.1002/srin.202100376 ◽

2021 ◽

Author(s):

Xiaoqian Pan ◽

Jian Yang ◽

Yinhui Zhang

Keyword(s):

Heat Affected Zone ◽

Heat Input ◽

High Heat ◽

Steel Plates ◽

Fracture Characteristics ◽

Shipbuilding Steel ◽

High Heat Input

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Grain Refinement of Heat Affected Zone in High Heat Input Welding by Liquid Phase Pinning of Oxy-Sulfide

ISIJ International ◽

10.2355/isijinternational.isijint-2015-033 ◽

2015 ◽

Vol 55 (9) ◽

pp. 2018-2026 ◽

Cited By ~ 4

Author(s):

Takako Yamashita ◽

Junji Shimamura ◽

Kenji Oi ◽

Masayasu Nagoshi ◽

Katsunari Oikawa ◽

...

Keyword(s):

Liquid Phase ◽

Grain Refinement ◽

Heat Affected Zone ◽

Heat Input ◽

High Heat ◽

High Heat Input

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

Volume 3: Materials Technology; Ocean Engineering; Polar and Arctic Sciences and Technology; Workshops ◽

10.1115/omae2003-37280 ◽

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.

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