Surface and Coatings Technology, ( ISI ), Volume (334), Year (2018-1) , Pages (461-470)

Title : ( Correlation between the surface coverage of severe shot peening and surface microstructural evolutions in AISI 321: A TEM, FE-SEM and GI-XRD study )

Authors: Sadegh PourAli , Ali Reza Kiani Rashid , Abolfazl Babakhani , Sannakaisa Virtanen ,

Citation: BibTeX | EndNote

Abstract

Severe shot peening (SSP) as a surface severe plastic deformation (S2PD) process over a wide range of coverages was applied to generate gradient microstructures with the grain size increasing from nanometer- and micron-scale to initial grain size on the surface layers of 321 stainless steel. The microstructural evolutions including the grain size distribution and phase transformation were systematically investigated in-depth for different surface coverages. GI-XRD, FE-SEM and TEM techniques were used to reveal the microstructure modification mechanisms as a function of the surface coverage. Experimental results show that dislocation slip plays a key role in the grain refinement of this alloy so that with increasing the surface coverage, different structures including dislocation walls, dislocation tangles, and lamella-shaped cells sequentially appear in the initial coarse grains. The results confirmed that these dense dislocation structures during ultrahigh plastic deformation produce ultrafine- (115-192 nm) and nano-grains (68-82 nm) to minimize the total energy of the system. In line with the grain refinement, the γ (austenite) → α̍ (strain-induced martensite) phase transformation is more affected as the plastic strain increases. So that the volume fraction of α̍ phase increases to 58.4 % for ultrahigh strains. Gradient variation of microhardness with the depth were also obtained for various samples.

Keywords

, Austenitic stainless steel, Shot penning, Surface coverage, Surface nanocrystallization (SNC), Dislocation tangles, TEM
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@article{paperid:1067235,
author = {PourAli, Sadegh and Kiani Rashid, Ali Reza and Babakhani, Abolfazl and Sannakaisa Virtanen},
title = {Correlation between the surface coverage of severe shot peening and surface microstructural evolutions in AISI 321: A TEM, FE-SEM and GI-XRD study},
journal = {Surface and Coatings Technology},
year = {2018},
volume = {334},
month = {January},
issn = {0257-8972},
pages = {461--470},
numpages = {9},
keywords = {Austenitic stainless steel; Shot penning; Surface coverage; Surface nanocrystallization (SNC); Dislocation tangles; TEM},
}

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%0 Journal Article
%T Correlation between the surface coverage of severe shot peening and surface microstructural evolutions in AISI 321: A TEM, FE-SEM and GI-XRD study
%A PourAli, Sadegh
%A Kiani Rashid, Ali Reza
%A Babakhani, Abolfazl
%A Sannakaisa Virtanen
%J Surface and Coatings Technology
%@ 0257-8972
%D 2018

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