low P content is a key point to ensure acceptable spot
weldability in terms of plug failure after destructive testing.
The highest hardness is obtained in TRIP steels with an
addition of Si (Ref 4, 5). The hardenability and hardness of the
steels decrease after replacing silicon with aluminum. Unfortunately,
a problem is the significant amount of non-metallic
inclusions in the fusion zone. Moreover, there is the risk of
obtaining a soft zone near the fusion line as a result of the
excessive stabilization of ferrite (Ref 14, 15). The problem can
be solved to some extent using TRIP steels with silicon
partially replaced by aluminum, where the total concentration
of these elements should not be lower than 1.5 wt% due to the
stabilization of retained austenite (Ref 2, 4). In previous
research, Grajcar et al. (Ref 13) carried out laser welding of Nbmicroalloyed
Si-Al TRIP steel sheets within a heat input range
from 0.037 to 0.053 kJ/mm. It was found that in order to avoid
excessive grain growth, the heat input value should be limited
to about 0.045 kJ/mm. Such an approach guarantees that goodquality
welds will be obtained, i.e., without undercuts, porosity,
and excessive metal evaporation.
The aim of the current research is a microstructural
characterization of laser welds in thermomechanically processed
Si-Al high-strength steel containing Nb and Ti microadditions.
low P content is a key point to ensure acceptable spotweldability in terms of plug failure after destructive testing.The highest hardness is obtained in TRIP steels with anaddition of Si (Ref 4, 5). The hardenability and hardness of thesteels decrease after replacing silicon with aluminum. Unfortunately,a problem is the significant amount of non-metallicinclusions in the fusion zone. Moreover, there is the risk ofobtaining a soft zone near the fusion line as a result of theexcessive stabilization of ferrite (Ref 14, 15). The problem canbe solved to some extent using TRIP steels with siliconpartially replaced by aluminum, where the total concentrationof these elements should not be lower than 1.5 wt% due to thestabilization of retained austenite (Ref 2, 4). In previousresearch, Grajcar et al. (Ref 13) carried out laser welding of NbmicroalloyedSi-Al TRIP steel sheets within a heat input rangefrom 0.037 to 0.053 kJ/mm. It was found that in order to avoidexcessive grain growth, the heat input value should be limitedto about 0.045 kJ/mm. Such an approach guarantees that goodqualitywelds will be obtained, i.e., without undercuts, porosity,and excessive metal evaporation.The aim of the current research is a microstructuralcharacterization of laser welds in thermomechanically processedSi-Al high-strength steel containing Nb and Ti microadditions.
การแปล กรุณารอสักครู่..