Investigation determines - relation between impact velocity and minimum number of impacts producing visible erosion, relation between high frequency fatigue stresses and number of cycles to failure, water-hammer stresses relation to high frequency endurance limit, erosion rate as exposure time function, and correlates experimental data with recent theory

Rudy, S. L.

Thiruvengadam, A.

English

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Figure 1. Impact of Water Jet by Test Specimen
June 1971	 Brief 71-10197 
.	 S NASA TECH BRIEF 
NA SA Headquarters
	
_4V 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
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Erosion of Metals by Multiple Impacts with Water 
Analytical and experimental investigations were 
conducted on the erosion of four metals by multiple 
impacts with water. The metals were: aluminum-
1100-0; type-316 stainless steel; annealed commer-
cially pure nickel; and an annealed titanium alloy, 
Ti-6A1-4V. Preliminary data were obtained for three 
turbine materials: Steelite-613, Udimet-700, and 
molybdenum alloy TZM. 
Specimens mounted on a disk, rotating horizontally 
at speeds up to 20,000 rpm, cut vertical jets of tap 
water at 293K (68°F) twice per revolution (Fig. 1). 
The impact velocity is related to the minimum number 
of impacts causing visible indentation. 
For the four metals, the fatigue strengths were 
experimentally determined as functions of the
numbers of cycles to failure, using a high-frequency 
fatigue apparatus (Fig. 2). These data were correlated 
with the impact velocity data, in terms of the water-
hammer pressure. 
The erosion rates were determined as functions 
of the test durations at different velocities. These 
data were then compared with a recently developed 
theory of erosion. The fatigue-life distribution curves 
were also determined. 
The specific objectives of the investigation were 
to: (1) determine the relation between impact velocity 
and the minimum number of impacts producing 
visible erosion; (2) determine the relation between 
high-frequency fatigue stresses and the number of 
cycles to failure; (3) determine the relation of 
water-hammer stresses (corresponding to impact ve-
locities) to the high-frequency endurance limit; (4) 
determine the rate of erosion as a function of exposure 
time; (5) correlate the experimental data with a recent 
theory; (6) evaluate the erosion rate's dependence 
on the velocity of impact; and (7) compare the 
liquid-impact and cvitation-erosion strengths for 
the four metals. 
Note: 
The following documentation may be obtained 
from:
National Technical Information Service 
Springfield, Virginia 22151 
Single document price $3.00 
(or microfiche $0.95) 
Reference: 
NASA-CR- 1288 (N69-19786), Experimental 
and Analytical Investigation on Multiple 
Liquid Impact Erosion 
(continued overleaf) 
This document was prepared under the sponsorship of the National 	 Government assumes .any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19710000196 2020-03-17T02:19:41+00:00Z
Patent status: 
No patent action is contemplated by NASA. 
Source: A. Thiruvengadam and S. L. Rudy of 
Hydronautics, Inc.
under contract to
NASA Headquarters
(HQN- 1059 1)
. 
Frequency 
Counter Oscilloscope 
Stack-Cooling Bath  
i_— Transducer Stack 
I	 i	 Displacement 
L	
j,,Pickup Coil 
Noda l Support  
Specimen 
Test Liquid M-j
Constant-Temperature Bath
I	 14295	 I Audio Oscillator 
200-Watt 
Amplifier 
Power Supply
Figure 2. Block Diagram of the Magnetostriction Apparatus Used 
for High-Frequency Fatigue Tests
. 
Brief 71-10197	 Category 04


Erosion of metals by multiple impacts with water

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