Microstructure, mechanical behavior, and crystallographic texture in a hot forged dual-phase stainless steel

Riad Badji,Mohammed Hadji,Charlie Kahloun,Bellel Cheniti,Thierry Chauveau,Brigitte Bacroix

doi:10.1007/s00170-021-07502-8

Abstract

In this work, the hot forging behavior of a dual phase stainless steel in the temperature range of 850–1250 °C was investigated. The study revealed the occurrence of a significant cracking phenomenon for processing temperatures below 950 °C that was attributed to the combined effect of intermetallic precipitation and severe deformation. EBSD examination highlighted the occurrence of continuous dynamic recrystallization in both ferrite and austenite microstructures for processing temperatures above 1050 °C. Increasing the hot forging temperature to 1250 °C increased the low angle grain boundaries fraction and lowered the one of the high angle grain boundaries. This was accompanied by a gradual change in the crystallographic texture of the material. The mechanical behavior investigation showed that the steel plasticity, sharply dropped after forging at 850°, was gradually recovered after hot forging at temperatures above 1050°C. This was confirmed by nanoindentation measurements that revealed a remarkable increase of the hardness and Young’s modulus of the steel after hot forging at 850°C and 950°C due to the dislocation nucleation and the σ phase precipitation at γ/δ interface. The enhancement of dislocation movement at the vicinity of the grain boundaries in the temperature range of 1050–1250 °C improved the global mechanical properties of the hot forged steel.

Highlights

During industrial fabrication processes, metallic materials undergo various microstructural transformations due to the thermal, mechanical or thermomechanical effect of the process
It is observed that hot forging at 850 and 950 °C results in a significant decrease in the ferrite volume fraction as a consequence of the phase formation
In this work, hot forging of a 2205 duplex stainless steels (DSS) performed in the temperature range of 850 to 1250 °C was investigated

Summary

Introduction

Metallic materials undergo various microstructural transformations due to the thermal, mechanical or thermomechanical effect of the process. Among the wide range of metallic materials, duplex stainless steels (DSS) are characterized by a dual phase microstructure constituted of austenite ( ) and ferrite ( ). Their combination of high mechanical properties and improved corrosion resistance makes them excellent choices for applications in several industrial domains such as petroleum, gas and petrochemical industries [1,2,3,4,5]. Patra et al [20] investigated the crystallographic texture evolution during thermomechanical processing of a lean DSS They pointed out that the ferrite was dominated by the Cube and rotated Cube components whereas austenite was mainly characterized by deformation textures such as Copper, Brass and rotated Goss. Moura et al [21] concluded that both ferrite and austenite exhibit texture heterogeneities due to the complexity of the thermomechanical process

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Results

Conclusion