ISSN:
1662-9752
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
The characteristics of Nd:YAG laser welded 600MPa grade TRIP(transformation inducedplasticity) and DP(dual phase) steels with respect to hardness, microstructures, mechanicalproperties and formability was investigated. A shielding gas was not used, and bead-on-platewelding was performed using various welding speeds at a power of 3.5kW.In the case of TRIP steel, the hardness was the highest at the fusion zone(FZ) and HAZ near the FZand decreased as the base metal was approached. The maximum hardness increased with increasingwelding speed to 3.6m/min and then remained. The microstructures of FZ and HAZ near the FZconsisted of ferrite and bainite for all welding speeds.In the case of DP steel, the maximum hardness was obtained at the HAZ near the FZ. It increasedrapidly to 2.1m/min and then showed nearly the same value. The difference between the maximumhardness of HAZ and that of FZ increased with decreasing welding speed. The microstructure of FZwas composed of acicular ferrite but the HAZ near the FZ contained bainite and ferrite at a lowwelding speed.Both steels had similar tensile properties and formabilities. In a perpendicular tensile test to theweld line, all specimens were fractured at the base metal, and the strengths were somewhat higherthan those of raw metals. In a parallel tensile test, the strengths of the joints were higher than thoseof raw materials but the elongations were lower. Formability was determined to be approximately80% as compared with raw material at the optimum conditions.Differences in hardness near the welded zone was dependant on the relative contents of ferrite
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/15/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.539-543.3967.pdf
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