Minimization of heat-affected zone size in welded ultra-fine grained steel under cooling by liquid nitrogen during laser welding

2006 ◽  
Vol 426 (1-2) ◽  
pp. 21-30 ◽  
Author(s):  
Hideki Hamatani ◽  
Yasunobu Miyazaki ◽  
Tadayuki Otani ◽  
Shigeru Ohkita
Keyword(s):  
Laser Welding ◽  
Liquid Nitrogen ◽  
Heat Affected Zone ◽  
Zone Size ◽  
Fine Grained

Minimization of Heat-Affected Zone Size in Welded Ultra-Fine Grained Steel under Cooling by Liquid Nitrogen during Laser Welding

2007 ◽  
Vol 539-543 ◽  
pp. 4063-4068 ◽  
Author(s):  
Hideki Hamatani ◽  
Yasunobu Miyazaki ◽  
Tadayuki Otani ◽  
Shigeru Ohkita
Keyword(s):  
Laser Welding ◽  
Liquid Nitrogen ◽  
Heat Affected Zone ◽  
Laser System ◽  
Heat Removal ◽  
Plate Temperature ◽  
Fine Grained ◽  
Laser Beam Irradiation ◽  
Average Grain Size ◽  
Plume Temperature

Ultra-fine grained steel (UFGS) with an average grain size of less than 1μm has been developed and is expected to demonstrate superior properties. However, its welded heat-affected zone, HAZ, substantially affecting the strength of a welded joint, will be easily softened after welding. Therefore, minimization of UFGS’s HAZ size during laser welding was carried out using the cooling conductor liquid nitrogen. It was found that a shielding gas with adequate flow rate for the liquid nitrogen depth was used to displace nitrogen on the area of laser beam irradiation to stabilize the weld bead. Also, because YAG laser system was mainly used because it has a lower laser induced plasma or plume temperature, which results in a decreased occurrence of pit and blowhole. HAZ size minimization strongly depends on the initial plate temperature. Reduced initial plate temperature shrinks the specific heated temperature range in which softening occurs. However, due possibly to decreasing thermal conductivity under room temperature, which prevents heat removal, the benefit of reducing the initial plate temperature is limited. The optimal initial temperature to minimize the HAZ size, in the present work, was found to be 123K.

Weld strength and heat-affected zone size in friction welded NFA and CostE

2021 ◽  
pp. 1-9
Author(s):  
Brandon Scott Taysom ◽  
Tracy W. Nelson ◽  
Carl D. Sorensen ◽  
Richard DiDomizio ◽  
Shenyan Huang ◽  
...  
Keyword(s):  
Heat Affected Zone ◽  
Weld Strength ◽  
Zone Size

Effects of Al Addition on the Microstructure of Fe-Mn-Si Ultra-Fine Grain Steel Welded Heat Affected Zone

2011 ◽  
Vol 299-300 ◽  
pp. 372-375
Author(s):  
Jin Gang Qi ◽  
Dong Jun Zhang ◽  
Zuo Fu Zhao ◽  
Shan Dai ◽  
Xiao Chen Liu
Keyword(s):  
Heat Affected Zone ◽  
Retained Austenite ◽  
Nucleation Kinetics ◽  
Growth Orientation ◽  
Fine Grained ◽  
Simulation Procedure ◽  
Fine Grain ◽  
Maximum Value ◽  
Al Addition ◽  
Al Additions

In order to improve toughness of the weld heat affected zone (HAZ) of ultra-fine grained (UFG) steel, a thermal simulation procedure of Fe-Mn-Si UFG steels with different Al addition was conducted and the corresponding microstructure was characterized and investigated. The results indicate that the maximum value on driving force of nucleation is ultra-fine grain steel with wtAl=0.6%, it has been explained in Nucleation kinetics that the grains are fine in UFG2. On the other hand, the bainite ferrite growth orientation has been increased. The toughness was remarkably enhanced in the steel welded heat affected zone. The formation of strie retained austenite and grain refinement of bainite ferrite in Fe-Mn-Si UFG steels with Al additions results in the increasing toughness of weld HAZ.

Study of heat-affected zone and mechanical properties of Nd-YAG laser welding process of thin titanium alloy sheet

2016 ◽  
Vol 1 (2) ◽  
pp. 51-58 ◽  
Author(s):  
Grzegorz Krolczyk ◽  
Aleksandar Sedmak ◽  
Uday Kumar ◽  
Somnath Chattopadhyaya ◽  
A. K. Das ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloy ◽  
Laser Welding ◽  
Heat Affected Zone ◽  
Welding Process ◽  
Alloy Sheet ◽  
Yag Laser ◽  
Laser Welding Process
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