Strain Evolution in Cold-Warm Forged Steel Components Studied by Means of EBSD Technique

Abstract

Electron BackScatter Diffraction (EBSD) in conjunction with Field-Emission Environmental Scanning Electron Microscopy (FEG-ESEM) has been used to evaluate the microstructural and local plastic strain evolution in different alloys (AISI 1005, AISI 304L and Duplex 2205) deformed by a single-stage cold and warm forging process. The present work is aimed to describe the different behavior of the austenite and ferrite during plastic deformation as a function of different forging temperatures. Several topological EBSD maps have been measured on the deformed and undeformed states. Then, image quality factor, distributions of the grain size and misorientation have been analyzed in detail. In the austenitic stainless steel, the γ-phase has been found to harden more easily, then α-phase and γ-phase in AISI 1005 and in duplex stainless steel, sequentially. Compared to the high fraction of continuous dynamic recrystallized austenitic zones observed in stainless steels samples forged at low temperatures, the austenitic microstructure of samples forged at higher temperatures, 600–700 °C, has been found to be mainly characterized by large and elongated grains with some colonies of fine nearly-equiaxed grains attributed to discontinuous dynamic recrystallization.

Improved Mechanical Properties of Two Twinning‐Induced Plasticity Steels with Novel Grain Morphology

“…The former was obviously large-elongated deformed grains, while the latter was virtually full of fined nearly equiaxed grains, as clearly seen in the local SEM image in the upper right corner of Figure 2c. The microstructure is similar to the results of austentic 304L and Duplex 2205 austenitic stainless steel warm formed at 700 C. [20] This means that austenitic steel with a low to medium stacking fault energy may present a similar microstructural feature with warm forging at a relatively high temperature such as 700 C. This typical partially recrystallized microstructural feature is considered to be attributed to discontinuous dynamic recrystallized (dDRX). [21] In addition, deformation twins generated during warm forging are also observed.…”

“…WF, however, has a huge number of GBs with a few dislocations, and the dominated LABs are mainly attributed to subgrain boundaries formed during warm forging process. [20,26] As samples strained to yielding point, the fraction of misorientation boundaries with angles of 0-2 was obviously increased, as shown in Figure 5d-f, especially for WF with the most significantly increased fraction of 0.252. However, the fraction of Σ3 boundaries in all samples is nearly unchanged.…”

Surface treatment response of AISI 2205 and AISI 304L steels: SMAT and plasma-nitriding

“…Low SFE promotes the formation of more mechanical twins and hence, higher hardness [24]. However, the γ-phase is relatively difficult to harden in AISI 2205 than in AISI 304L [25]. In AISI 2205, the total deformation distributes among the grains of both phases ( γ and α ).…”