Effect of Carbon Content and Intercritical Annealing on Microstructure and Mechanical Tensile Properties in FeCMnSiCr TRIP-Assisted Steels

Abstract

Four TRIP (Transformation Induced Plasticity) assisted steels, three TBF (TRIP Bainitic Ferrite) steels and one TPF (TRIP Polygonal Ferrite) steel, were manufactured from three different carbon contents (0.2, 0.3 and 0.4 wt.% C), to study the evolution of their microstructure and tensile mechanical properties in 15 mm thick plates. TBF steels were subjected to the same austenitization heat treatment and subsequent bainitization isothermal treatment. The TPF steel was subjected to an intercritical annealing and subsequent isothermal bainitization treatment. All were microstructurally characterized by optical, scanning electron and atomic force microscopy, as well as X-ray diffraction. Mechanically, they were characterized by the ASTM E8 tensile test and fractographies. For the TBF steels, the results showed that when the carbon content increased, there were an increase in volume fraction of retained austenite, of the microconstituent “martensite/retained austenite” and in the tensile strength; and a decrease in the volume fraction of bainitic ferrite matrix and elongation; with an improvement in TRIP behavior due to the increase in retained austenite. The TPF steel presented around 50% ductile polygonal ferrite developing better TRIP behavior than the TBF steels. The evolution of the fractographies was ductile to brittle for TBF steels with an increase in carbon content, and for TPF, the appearance of the fracture surface was ductile.

Exploring the Manufacturing Process of a Renaissance Breach Pike

“…The othe of section S3 are characterized by ferritic-pearlitic zones (F + P) (Figure 10c) surr mainly pearlitic regions with a minor amount of idiomorphic, allotriomorphic, a The etched transverse section S4 taken from the end portion of the spike ex complex microstructure (Figure 11a). The majority of the section is characterized b ture of ferrite-austenite aggregates, often referred to as granular bainite (GB), w martensite/retained austenite islands (MA) and ferrite (F) (Figure 11b; high-magn SEM-SE image in Figure 12a) [21,22].…”

“…The etched transverse section S4 taken from the end portion of the spike exhibited a complex microstructure (Figure 11a). The majority of the section is characterized by a mixture of ferrite-austenite aggregates, often referred to as granular bainite (GB), with large martensite/retained austenite islands (MA) and ferrite (F) (Figure 11b; high-magnification SEM-SE image in Figure 12a) [21,22].…”

Effect of Austempering Parameters on Microstructure and Tensile/Impact Behaviours of Micro-Alloyed TRIP-Assisted Steel

“…The ultimate tensile strength (UTS) of classic C-Mn-Si(Al) TRIP-assisted steels typically lies in the range of 700-980 MPa, while a total elongation (TE) is 20-40 % [13]. Further increase in the level of steel properties can be attained by an additional alloying of steel with the appropriate adjustment of heat treatment mode [14][15][16][17]. Micro-adding of carbide-forming elements leads to increasing the steel's hardenability and strength through changing thermodynamics and kinetics of the transformation and employing different structural mechanisms [18][19][20].…”