Indian Welding Journal

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Laser Welding of Ultrafine Bainitic Steels


Affiliations
1 Mahatma Gandhi Institute of Technology, Gandipet, Hyderabad - 500 075, India
2 School of Engineering Sciences and Technology, University of Hyderabad - 500 046, India
3 Defence Metallurgical Research Laboratory, Hyderabad - 500 058, India
4 Defence Research Development Laboratories, Hyderabad - 500 058, India
5 Ministry of Steel Chair Professor, MGIT, Hyderabad - 500 075, India
     

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Laser beam welding (LBW) is one of the advanced welding process which results in joining of materials with intense heat. The intense heat is produced using focused light source falling upon the metallic material’s surfaces to be welded. The coherent laser beam is a known source of electromagnetic energy or light with single frequency which can be projected without diverging and also can be focused to an exact spot. The current investigation aims at establishing the parameters required for producing sound welds by fibre laser beam welding and identifying the evolution of microstructure in bainitic steel during similar welding of three mm thick plates. Sound welding was accomplished with laser power 3.5kW and at traverse speeds of 2000, 3000 and 4000 mm/min. The weld joints revealed base metal, weld zone and heat affected zones. The widths of weld zone and HAZ varied as a function of welding speed. Weld zone displayed hardness around 750-800 VHN. A sudden drop in hardness was observed across the heat affected zone, reaching a dip in the intercritical region of HAZ. Hardness in ICHAZ reached around 400-450VHN. The ICHAZ was more pronounced at 3000 mm/min. Microstructural changes were explored by optical microscopy techniques. The high hardness in fusion zone and low hardness in the intercritical structure was found to have correlation with prevailing microstructural features in the respective zones.


Keywords

Bainitic Steel, Fibre Laser Welding, Fusion Zone, Heat Affected Zone, Intercritical Structure, Hardness.
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  • Laser Welding of Ultrafine Bainitic Steels

Abstract Views: 409  |  PDF Views: 7

Authors

V. S. M. Ramakrishna R.
Mahatma Gandhi Institute of Technology, Gandipet, Hyderabad - 500 075, India
Jai Prakash Gautam
School of Engineering Sciences and Technology, University of Hyderabad - 500 046, India
G. Madhusudhan Reddy
Defence Metallurgical Research Laboratory, Hyderabad - 500 058, India
P. Masthanaiah
Defence Research Development Laboratories, Hyderabad - 500 058, India
K. Bhanu Sankara Rao
Ministry of Steel Chair Professor, MGIT, Hyderabad - 500 075, India

Abstract


Laser beam welding (LBW) is one of the advanced welding process which results in joining of materials with intense heat. The intense heat is produced using focused light source falling upon the metallic material’s surfaces to be welded. The coherent laser beam is a known source of electromagnetic energy or light with single frequency which can be projected without diverging and also can be focused to an exact spot. The current investigation aims at establishing the parameters required for producing sound welds by fibre laser beam welding and identifying the evolution of microstructure in bainitic steel during similar welding of three mm thick plates. Sound welding was accomplished with laser power 3.5kW and at traverse speeds of 2000, 3000 and 4000 mm/min. The weld joints revealed base metal, weld zone and heat affected zones. The widths of weld zone and HAZ varied as a function of welding speed. Weld zone displayed hardness around 750-800 VHN. A sudden drop in hardness was observed across the heat affected zone, reaching a dip in the intercritical region of HAZ. Hardness in ICHAZ reached around 400-450VHN. The ICHAZ was more pronounced at 3000 mm/min. Microstructural changes were explored by optical microscopy techniques. The high hardness in fusion zone and low hardness in the intercritical structure was found to have correlation with prevailing microstructural features in the respective zones.


Keywords


Bainitic Steel, Fibre Laser Welding, Fusion Zone, Heat Affected Zone, Intercritical Structure, Hardness.

References





DOI: https://doi.org/10.22486/iwj.v52i3.184311