Effect Of The Application Of Constant And Variable Temperatures at the Overaging Stage in the Mechanical Properties of Trip780 Steel

Rafael Ricardo Magalhães,Fernando De Souza Costa,Berenice Mendonça Gonzalez

doi:10.1590/1980-5373-mr-2019-0088

Rafael Ricardo Magalhães, Fernando De Souza Costa + Show 1 more

Open Access

https://doi.org/10.1590/1980-5373-mr-2019-0088

Copy DOI

Abstract

The effect of the application of constant temperatures (isothermal plateau) and variables (cooling ramp) during the overaging (OA) stage of the continuous annealing cycle in the microstructural characteristics and mechanical properties of a TRIP steel of the class of 780 MPa was investigated. It was simulated six overaging conditions in the equipment Gleeble. The microstructures presented variable fractions of ferrite, bainite, retained austenite and a small martensite portion. All the conditions achieved the minimum strength of 780 MPa it is possible to highlight the conditions for initial OA temperature of 440 °C where presented the best results of mechanical properties and typical TRIP steels behaviors.

Highlights

In recent years, one of the main objectives of the automotive industry is to reduce the weight of vehicles in order to reduce fuel consumption and, the emission of gases from the burning of hydrocarbons, which contribute to the greenhouse effect
The Transformation Induced Plasticity (TRIP) steels are characterized by superior results in terms of mechanical strength and uniform elongation, as well as higher impact energy absorption capacity compared to Dual Phase (DP) and High Strength Low Alloy (HSLA) steels with the same degree of mechanical strength[1,2]
The retained austenite, which is a metastable constituent at room temperature, is essential for obtaining the set of mechanical properties presented by this type of steel

Summary

Introduction

One of the main objectives of the automotive industry is to reduce the weight of vehicles in order to reduce fuel consumption and, the emission of gases from the burning of hydrocarbons, which contribute to the greenhouse effect. In order to meet all of the needs described above, the steel industries have started investing in the development of new steels technologically more advanced for application in vehicles. In this scenario, the called Advanced High Strength Steels (AHSS) were developed[1]. Its microstructure is typically composed of polygonal ferrite (F), bainite (B) and retained austenite (RA)[3,4]. The retained austenite, which is a metastable constituent at room temperature, is essential for obtaining the set of mechanical properties presented by this type of steel

Methods

Discussion

Conclusion