0
Research Papers: Applications

Improving Erosion Resistance of Hydroturbine Steel Using Friction Stir Processing

[+] Author and Article Information
H. S. Grewal, Anupam Agrawal

School of Mechanical, Materials
and Energy Engineering,
Indian Institute of Technology Ropar,
Rupnagar, Punjab 140001, India

H. S. Arora

School of Mechanical, Materials
and Energy Engineering,
Indian Institute of Technology Ropar,
Rupnagar, Punjab 140001, India
Department of Materials Science
and Engineering,
University of North Texas,
Denton, TX 76203

H. Singh

School of Mechanical, Materials
and Energy Engineering,
Indian Institute of Technology Ropar,
Rupnagar, Punjab 140001, India
e-mail: harpreetsingh@iitrpr.ac.in

S. Mukherjee

Department of Materials Science
and Engineering,
University of North Texas,
Denton, TX 76203

1Corresponding author.

Contributed by the Tribology Division of ASME for publication in the JOURNAL OF TRIBOLOGY. Manuscript received June 1, 2013; final manuscript received April 26, 2014; published online June 6, 2014. Assoc. Editor: Jordan Liu.

J. Tribol 136(4), 041102 (Jun 06, 2014) (10 pages) Paper No: TRIB-13-1115; doi: 10.1115/1.4027622 History: Received June 01, 2013; Revised April 26, 2014

In the present work, the slurry erosion behavior of friction stir processed (FSPed) hydroturbine steel (CA6NM) was investigated. For comparison, the erosion performance of unprocessed CA6NM steel was evaluated under similar conditions. Friction stir processing (FSP) is a microstructural refinement tool which is useful in enhancing the bulk and surface properties of materials. An in-depth characterization of both steels was done using an optical microscope (OM), a scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS), the electron backscatter diffraction (EBSD) technique, and micro- and nano-indentation techniques. The FSP of the steel helped in reducing the erosion rates by 50% to 60%, depending upon the impingement angle. The improved performance of the FSPed steel in comparison to unprocessed steel was attributed to microstructural refinement, which increased the hardness and yield strength. At an oblique impingement angle, plowing, along with microcutting, was observed to be the dominant erosion mechanism. At a normal impingement angle, the material removal process was controlled by the platelet mechanism of erosion. A modified form of the mathematical model for predicting the erosion rates of the ductile materials, proposed by authors earlier, was also presented. This modified model based upon the theory of plasticity was able to predict the erosion rates with an accuracy of ±20%.

FIGURES IN THIS ARTICLE
<>
Copyright © 2014 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Fig. 1

Schematic illustrating the basic principle and process parameters for the friction stir processing technique

Grahic Jump Location
Fig. 2

Illustration showing the setup used for the friction stir processing of CA6NM steel

Grahic Jump Location
Fig. 3

Particle size distribution of sand used for the slurry erosion testing

Grahic Jump Location
Fig. 4

Schematic illustrating the slurry erosion test rig used for experimentation

Grahic Jump Location
Fig. 5

Micrographs showing the microstructure of the (a) unprocessed CA6NM steel and (b) transition zone of processed CA6NM steel

Grahic Jump Location
Fig. 6

The EBSD micrographs and inverse pole figure of the (a) unprocessed and (b) nugget zone of the processed CA6NM steel along with the grain size distribution maps

Grahic Jump Location
Fig. 7

(a) Schematic showing the designation system employed for identifying different processing directions and zones. The {001} pole figure of the (b) unprocessed and (c) nugget zone of the FSPed CA6NM steel.

Grahic Jump Location
Fig. 14

Comparison of the erosion rates of unprocessed and FSPed CA6NM steel at a 90 deg impingement angle predicted by the proposed energy and Sundararajan‘s [40] model with the experimental results

Grahic Jump Location
Fig. 13

Micrographs showing the morphology of the eroded (a) unprocessed CA6NM steel at 30 deg, (b) FSPed CA6NM steel at 30 deg, (c) unprocessed CA6NM steel at 90 deg, (d) FSPed CA6NM steel at 90 deg, (e) high magnification image of the FSPed CA6NM steel at 30 deg, and (f) high magnification image of the FSPed CA6NM steel at a 90 deg impingement angle, 16 m/s velocity, and 0.5 wt.% sand concentration

Grahic Jump Location
Fig. 9

Load-displacement plot for the FSPed and unprocessed CA6NM steel obtained using the nano-indentation technique

Grahic Jump Location
Fig. 8

Variation in the microhardness of the FSPed CA6NM steel with the distance from the top surface

Grahic Jump Location
Fig. 12

Comparison of the steady state erosion rates of FSPed (1) and unprocessed CA6NM (2) steel at 30 deg and 90 deg impingement angles, 16 m/s velocity, and 0.5 wt.% sand concentration

Grahic Jump Location
Fig. 11

Plot showing the variation of erosion rates with time for the FSPed and unprocessed CA6NM steel at 30 deg and 90 deg impingement angles, 16 m/s velocity, and 0.5 wt.% sand concentration

Grahic Jump Location
Fig. 10

Volume loss-time plot for the FSPed and unprocessed CA6NM steel at 30 deg and 90 deg impingement angles, 16 m/s velocity, and 0.5 wt.% sand concentration

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In