Effect of TMCP on Microstructure and Mechanical Properties of 304 Stainless Steel

Abstract

The present study investigates the evolution of microstructure and mechanical properties of 304 stainless steel after thermo‐mechanical controlled processing (TMCP). Three different FRTs (finish rolling temperatures) have been adopted and the micro‐constituents are identified as austenite grains, stacking faults, annealing, and deformation twins. Fine austenite grains in the range of 1–30 μm are obtained at lower FRT (700 °C) whereas at higher FRT, coarse grains are formed. TEM and X‐ray analyses indicate the formation of M23C6 ((Cr, Fe)23C6) precipitates for higher FRT (900 °C). Specimen processed with 700 °C FRT results into 37% enhancement in UTS compared to the base metal which is attributed to fine partially recrystallized grain, extensive deformation twinning and high dislocation density. Maximum elongation (68%) is obtained due to the formation of strain‐free equiaxed grains (≈40 μm) at 900 °C FRT.

Failure Analysis of HP40 Steel Tubes utilized in Steam Reformer Units of Petroleum Refinery Plants

“…The EDX analysis of M 7 C 3 carbides also indicated a Cr-rich carbide for this specimen. Both the calculated and experimental results of the present work are in good agreement with the phase reported for this type of steels in the literature [7][8][9][10][11][12][13][14][15][22][23][24][25] .…”

“…The HP40 steel is used in the as-cast condition, and its high content of Cr and Ni promotes a microstructure composed of a net of primary eutectic precipitates (γ + M 7 C 3 ) located in the dendritic boundaries of an fcc γ austenitic phase [3][4][5][6][7][8] . These Cr-rich M 7 C 3 carbides are known as primary carbides and they perform an important role on the prevention of sliding of the austenite grain boundaries at high temperatures [8][9][10][11][12] Besides, Nb-rich MC carbides can be formed during the solidification process, which also contributes to improve its mechanical strength. The secondary fine precipitation of Cr-rich carbides, M 23 C 6 with cubic morphology , restrict the movement of the dislocations, making of this alloy an excellent option to these operating conditions [13][14][15] .…”

“…The volume fraction of this precipitation has been reported 14 to increase with carbon content of steel. This precipitation also contributes to increase the wear resistance of these alloys [8][9][10][11][12][13][14][15] .…”

Effects of Grain Size on Mechanical Properties and Work‐Hardening Behavior of AISI 304 Austenitic Stainless Steel

“…Regarding ASSs, due to the absence of a notable phase transformation during the thermal treatment, grain refinement has been achieved by static recrystallization (SRX), dynamic recrystallization (DRX), formation and reversion of strain‐induced martensite, and various severe plastic deformation techniques . In fact, many commercial ASSs are metastable against the martensitic transformation during deformation.…”

Thermomechanical Control of Microstructure and Precipitation in Vanadium Microalloyed Steel: Influence of Finish Rolling and Coiling Temperatures

“…Currently, there is much interest in studying the thermomechanical processing and accelerated cooling of HSLA steels to optimize mechanical properties, especially the strength-toughness combinations. [5,7,8] It is worth mentioning that thermomechanical controlled process (TMCP) techniques can improve the mechanical properties of microalloyed steels by refining the microstructure without changing the composition. [9,10] These TMCP techniques consist mainly of controlled rolling and controlled cooling processes.…”