Characterisation on Al-bearing hot-rolled TRIP steel produced through isothermal bainite transformation

Shen

et al. 2023

steel research int.

Self Cite

Herein, a medium‐Mn steel containing 4 wt% Mn is designed to achieve ultrahigh tensile strength and good ductility by the quenching and tempering process. The effects of tempering temperature on the microstructure, tensile behavior, and fracture properties under different stress states are explored. It is observed that tempering temperature influences the fracture mechanisms of the ultrahigh‐strength steels. Both ductile fracture strain and cleavage fracture strength of the investigated medium‐Mn steel are affected by the tempering temperature. The impacts of tempering temperature on volume fraction, carbon content of retained austenite (RA), and tensile properties are quantitatively analyzed. Detailed microstructure analysis reveals that both volume fraction and carbon content of the RA are increased in the tempered steels, accompanied by improved tensile properties than in quenched conditions. The superior tensile properties are achieved after tempering at 250 °C, with the ultrahigh yield strength of 1590 MPa, ultrahigh tensile strength of 1963 MPa, and total elongation of 12%. The corresponding relationship between microstructure and mechanical properties is investigated, with a focus on the change of residual stress, the occurrence of carbon redistribution/carbide precipitation, the decrease of dislocation density of martensite, and the presence of transformation‐induced plasticity effect during deformation.

Section: Resultsmentioning

confidence: 99%

Effect of Tempering Temperature on the Microstructure, Deformation and Fracture Properties of an Ultrahigh Strength Medium‐Mn Steel Processed by Quenching and Tempering

Shen

et al. 2023

steel research int.

Self Cite

“…The base metal microstructure of TRIP steel is mainly constituted with a ferrite matrix along with trace amounts of martensite, bainite, and confined austenite alloys [20]. In plastic bucklings, austenite is converted into martensite to achieve superior extension steels with their excellent combination of strength and ductility [21] and [22].…”

Section: Introductionmentioning

confidence: 99%

An Investigation on Laser Welding Parameters on the Strength of TRIP Steel

Suresh

Rao²,

Natu³

et al. 2021

SV-JME

The energy required for joining steel segments by using laser welding is relatively very low compared with arc welding, gas welding, or any other conventional welding techniques. Moreover, the rapid cooling may create a significant effect on different regions, such as the fusion zone (FZ), heat affected zone (HAZ), and base metal (BM), and in turn affect different parameters. In this study, the characteristics of the laser-welded joint were investigated by varying laser power, welding velocity and incident angle, and tensile strength. In our, experiments. the microhardness was increased by varying the power of laser welding. The strength of the joint was increased to 549 MPa with 2200 W high power, 30 mm/s velocity, and 80º laser incident angle. By increasing the power and velocity of the laser, the welding gun strength was improved; conversely, the angle of laser incident on the welding location decreased while its strength was increased.

Chemical Composition Optimization and Isothermal Transformation of δ‐Transformation‐Induced Plasticity Steel for the Third‐Generation Advanced High‐Strength Steel Grade

Okur,

Davut,

Palumbo

et al. 2024

steel research int.

A new low‐manganese transformation‐induced plasticity steel is designed with optimized nickel content to achieve superior strength and ductility while minimizing the use of expensive nickel. The steel is optimized using JMatPro software, then cast, and hot rolled. To assess the effect of intercritical annealing on austenite (martensite at room temperature) volume fraction and carbon content, hot‐rolled steel samples quenched from different annealing temperatures (680–1100 °C) are used. Additionally, hot‐rolled steel coupons are intercritically annealed at about 50% austenite formation temperature (740 °C) and then subjected to isothermal treatments at 300–425 °C for varying times (10–90 min). After optimizing these treatments to maximize retained austenite (RA), tensile specimens are heat‐treated first at 740 °C and then isothermally at 325 °C. Thermodynamic calculations suggest that aluminum combined with silicon may lead to the δ ferrite formation, and even minimal nickel content can stabilize a considerable amount of austenite. In the experimental studies, it is shown that lower‐temperature bainitic holding enhances austenite stability by enriching the carbon content. Optimized two‐stage heat treatments yield up to 25.8% RA, with a tensile strength of 867.2 MPa and elongation of 40.6%, achieving a strength‐elongation product of 35.2 GPa×%, surpassing the third‐generation advanced high‐strength steel grades minimum requirement of 30 GPa×%.