I. INTRODUCTION
ADVANCED high-strength steels (AHSSs) are
promising solutions for the production of lighter automobiles,
which exhibit reduced fuel consumption and
increased passenger safety due to improved crashworthiness.
Transformation-induced plasticity (TRIP)
steels are one class of AHSSs that offer high strength
and toughness combinations with uniform elongation of
about 20 to 35 pct.[1] Along with these properties, these
steels also have an ability to absorb more energy during
a crash due to the delayed transformation of retained
austenite (RA) to martensite upon deformation.[2]
However, the higher alloying content of these steels
limits weldability, and the thermal cycle of a welding
process destroys the carefully designed microstructure,
which results in inferior mechanical properties of the
weld. In order to improve the commercial applicability
of these steels, it is necessary to improve weldability by
understanding the welding behavior with emphasis on
specific welding processes and their thermal cycles, as
well as the effects of alloying additions on the evolution
of the weld and heat-affected zone (HAZ) microstructures.
Cretteur et al.[3,4] attempted to improve the
weldability of TRIP steels by pre- and postweld heat
treatments during resistance spot welding and reported
better mechanical properties with modified weld thermal
profiles. Studies on the influence of CO2 laser welding
I. INTRODUCTION
ADVANCED high-strength steels (AHSSs) are
promising solutions for the production of lighter automobiles,
which exhibit reduced fuel consumption and
increased passenger safety due to improved crashworthiness.
Transformation-induced plasticity (TRIP)
steels are one class of AHSSs that offer high strength
and toughness combinations with uniform elongation of
about 20 to 35 pct.[1] Along with these properties, these
steels also have an ability to absorb more energy during
a crash due to the delayed transformation of retained
austenite (RA) to martensite upon deformation.[2]
However, the higher alloying content of these steels
limits weldability, and the thermal cycle of a welding
process destroys the carefully designed microstructure,
which results in inferior mechanical properties of the
weld. In order to improve the commercial applicability
of these steels, it is necessary to improve weldability by
understanding the welding behavior with emphasis on
specific welding processes and their thermal cycles, as
well as the effects of alloying additions on the evolution
of the weld and heat-affected zone (HAZ) microstructures.
Cretteur et al.[3,4] attempted to improve the
weldability of TRIP steels by pre- and postweld heat
treatments during resistance spot welding and reported
better mechanical properties with modified weld thermal
profiles. Studies on the influence of CO2 laser welding
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