Abstract:The aim of the present study was to examine the feasibility of achieving a better combination of yield strength, ductility, and corrosion resistance of δ‐TRIP steel through the concept of microalloying. Three δ‐TRIP steels with different contents of Nb (0, 0.025, 0.076 wt%) were subjected to the microstructural, mechanical, and electrochemical examination. ASTM A283 and ASTM A516 steels were taken as comparative samples. The obtained results revealed a threefold increase in strength × ductility products of TRI… Show more
“…After that, the samples were cooled down to ambient temperature. It is notable that the IA temperature is selected based on the previous study by Gholami Shiri et al [4] who indicated that the IA temperature ranges between 734 and 845°C based on differential thermal analysis results. Figure 1 Schematic illustration of the heat treatment procedure.…”
Section: Methodsmentioning
confidence: 99%
“…Transformation-induced-plasticity (TRIP) steels have been considered as a candidate for advanced energy materials owing to the outstanding combination of strength, ductility and high energy absorption as well as excellent fatigue properties [1-5]. It is known that the main phases that exist in the microstructure of TRIP steels involve ferrite, bainite, retained austenite and martensite [1].…”
This study aims to clarify effects of isothermal bainitic transformation (IBT) temperature on microstructure and mechanical properties of a high Al–low Si δ-TRIP steel. For this purpose, the alloy was austenitised at the intercritical annealing temperature of 820°C for 600 s and then was isothermally cooled down into a salt bath and held at the temperatures between 350 and 450°C for 360 s. X-ray diffraction indicates that by increasing the IBT temperature, the volume fraction of retained austenite increases. In addition, it was found that the optimum combination of strength and ductility, i.e. tensile strength of 1046 MPa and total elongation of 54%, was achieved in the sample which was isothermally held at 450°C for 360 s.
“…After that, the samples were cooled down to ambient temperature. It is notable that the IA temperature is selected based on the previous study by Gholami Shiri et al [4] who indicated that the IA temperature ranges between 734 and 845°C based on differential thermal analysis results. Figure 1 Schematic illustration of the heat treatment procedure.…”
Section: Methodsmentioning
confidence: 99%
“…Transformation-induced-plasticity (TRIP) steels have been considered as a candidate for advanced energy materials owing to the outstanding combination of strength, ductility and high energy absorption as well as excellent fatigue properties [1-5]. It is known that the main phases that exist in the microstructure of TRIP steels involve ferrite, bainite, retained austenite and martensite [1].…”
This study aims to clarify effects of isothermal bainitic transformation (IBT) temperature on microstructure and mechanical properties of a high Al–low Si δ-TRIP steel. For this purpose, the alloy was austenitised at the intercritical annealing temperature of 820°C for 600 s and then was isothermally cooled down into a salt bath and held at the temperatures between 350 and 450°C for 360 s. X-ray diffraction indicates that by increasing the IBT temperature, the volume fraction of retained austenite increases. In addition, it was found that the optimum combination of strength and ductility, i.e. tensile strength of 1046 MPa and total elongation of 54%, was achieved in the sample which was isothermally held at 450°C for 360 s.
“…Numerous articles in this context have studied the effects of alloying elements, [14][15][16][17] initial and evaluated microstructure, 18,19 heat-treatment processes, 18,20 and heating rate on the microstructure and mechanical properties. Conventional TRIP-assisted steel is produced by a two-stage heat-treatment process.…”
This research was done to investigate third-generation Advanced High-Strength Steel (AHSS) to improve mechanical properties and reduce production costs in the automotive industry. The potential of TRIP-assisted steel has been studied to address this issue, with a special focus on δ-TRIP steels. This research studied the δ-TRIP samples, which were micro-alloyed with 0.05 and 0.30 wt.% Mo, with isothermal bainitic transformation (IBT) time parameters. Microstructural analyses were conducted using optical microscopy (OM), field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectrometry (EDX). The volume percentage of retained austenite (RA) phase, critical to achieving the requisite mechanical characteristics, was determined using X-ray diffraction (XRD). The analysis of the samples revealed a complex, multi-phased structure comprising δ-ferrite matrix, α-ferrite, bainite, RA, and martensite. The quantity and morphology of RA significantly influenced the resulting mechanical characteristics. The experimental results demonstrated yield stresses (YS) of 400–440 MPa, ultimate tensile strength (UTS) of 790–870 MPa, and total elongations to failure (TEL) of 24–34% in δ-TRIP steels containing 0.05 and 0.30 wt.% Mo alloy. The optimal combination of UTS and TEL (UTS × TEL) is achieved at an impressive 850 MPa × 32% (27200 MPa.%). This remarkable achievement was made possible by adding only 0.30 wt.% Mo and IBT, which were carried out at 450°C for 10 min. Focusing on the effects of Mo-alloy content and heat treatment duration on microstructure and mechanical characteristics, this study provided insights into enhancing the quality of δ-TRIP steel while decreasing manufacturing costs.
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