Influence of heat input on microstructure and fracture toughness property in different zones of X80 pipeline steel weldments

In this paper, microstructure observations and mechanical behaviour of fusion line and offsetting positions from fusion line by 1, 2 and 3 mm were analysed. For the welding of X80 pipeline steel plates, different magnitudes of heat inputs such as high heat input (HHI) 25 kJ/cm, medium heat input (MH...

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Bibliographic Details
Published in:Fatigue & fracture of engineering materials & structures 2021-01, Vol.44 (1), p.85-100
Main Authors: Singh, Mayur Pratap, Arora, Kanwer Singh, Kumar, Rajneesh, Shukla, Dinesh Kumar, Siva Prasad, S.
Format: Article
Language:English
Subjects:
Bainite
Constituents
Crack opening displacement
Crack tips
Fracture toughness
HAZ
Heat treating
High strength low alloy steels
Inclusions
Mechanical properties
Microstructure
Molybdenum
Steel plates
Structural steels
Titanium
welded joint
Weldments
X80 pipe line steel
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Summary:In this paper, microstructure observations and mechanical behaviour of fusion line and offsetting positions from fusion line by 1, 2 and 3 mm were analysed. For the welding of X80 pipeline steel plates, different magnitudes of heat inputs such as high heat input (HHI) 25 kJ/cm, medium heat input (MHI) 20 kJ/cm and low heat input (LHI) 15 kJ/cm were employed. Critical values of J‐integral (J0.2) and crack tip opening displacement (CTOD0.2) for predetermined regions in the X80 weldment were determined as per ASTM‐E1820a. M‐A constituents of different sizes such as small (1–2 μm), large >2 μm and slender (>4 μm) were observed in the microstructure of subzones of weldments for different heat inputs. Formation of granular bainite, M‐A constituents and inclusions of Ti, Si, Mo in the microstructure impaired fracture toughness property. In the X80 weldment, the fusion line (FL) for HHI was found weakest in terms of fracture resistance, which subsequently increases the risk of fracture.
ISSN:8756-758X
1460-2695
DOI:10.1111/ffe.13333