Cavitation damage resistance of materials in liquid sodium

The cavitation damage resistance of alloys of aluminum, columbium (niobium), tantalum, molybdenum, and stainless steel was evaluated in water using a rotating disk apparatus that simulated the cavitation vortex patterns encountered in pumps operating at high suction specific speed. The alloys in decreasing order of cavitation resistance were Ta-8W-2Hf, Cb-18W-8Hf, Ta-10W, 316SS, Mo-.5Ti, Cb-1Zr, Al-4Cu-.7Mn-.5Mg, and Al-2.5Mg-.25Cr. The damage resistance order does not follow the variation of any single property such as strain energy to failure, yield strength, or hardness, but appears to be a combination of mechanical properties and phase structure. Photomicrographs show predominant intergranular cracking for the molybdenum alloy and transgranular erosion and cracking for the remaining alloys tested. The second phase precipitate in the aluminum alloy appears to hinder the erosion of material. Investigation of small variations in the grain size of the heat-treated Cb-1Zr alloys resulted in some variation in damage resistance, with the largest grain structure exhibiting the highest resistance. Correlation curves of volume loss as a function of the peripheral velocity are presented for all materials tested. In addition, the operation of the rotating disk apparatus itself was examined in considerable detail and the effects of various design changes were evaluated.

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Mechanical Properties of Metals and Their Cavitation-Damage Resistance

Journal of Ship Research ◽

10.5957/jsr.1966.10.1.1 ◽

1966 ◽

Vol 10 (01) ◽

pp. 1-9

Author(s):

A. Thiruvengadam ◽

Sophia Waring

Keyword(s):

Mechanical Properties ◽

Steady State ◽

Strain Energy ◽

Fracture Strain ◽

Bubble Collapse ◽

Strain Diagram ◽

Volume Loss ◽

Damage Resistance ◽

Cavitation Damage ◽

Energy Absorbing

Detailed investigations with a magnetostriction apparatus were carried out to determine the cavitation-damage resistance of eleven metals in distilled water at 80 F. The cavitation-damage resistance is defined as the reciprocal of the rate of volume loss for a given metal. Among the mechanical properties investigated (ultimate tensile strength, yield strength, ultimate elongation, Brinell hardness, modulus of elasticity and strain energy) the most significant property which characterizes the energy-absorbing capacity of the metals, under the repeated, indenting loads due to the energy of cavitation bubble collapse in the steady-state zone, was found to be the fracture strain energy of the metals. The strain energy is defined as the area of the stress-strain diagram up to fracture. The correlation between the strain energy and the reciprocal of the rate of volume loss leads directly to the estimation of the intensity of cavitation damage; this intensity varies as the square of the displacement amplitude of the specimen. All these conclusions are limited to the steady-state zone of damage.

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Cavitation Damage in Flowing Liquid Sodium Using Venturi Test Section

Journal of Power and Energy Systems ◽

10.1299/jpes.5.77 ◽

2011 ◽

Vol 5 (1) ◽

pp. 77-85 ◽

Cited By ~ 2

Author(s):

Teddy ARDIANSYAH ◽

Minoru TAKAHASHI ◽

Makoto ASABA ◽

Kuniaki MIURA

Keyword(s):

Test Section ◽

Liquid Sodium ◽

Flowing Liquid ◽

Cavitation Damage

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High-Frequency Fatigue of Metals and Their Cavitation-Damage Resistance

Journal of Engineering for Industry ◽

10.1115/1.3670956 ◽

1966 ◽

Vol 88 (3) ◽

pp. 332-340 ◽

Cited By ~ 7

Author(s):

A. Thiruvengadam

Keyword(s):

Strain Rate ◽

High Frequency ◽

Strain Energy ◽

Fatigue Tests ◽

Strain Rate Effects ◽

Damage Resistance ◽

Cavitation Damage ◽

Rate Effects ◽

Plastic Strain Energy ◽

Hardening Factor

In order to verify the strain-rate effects on the correlation between strain energy of metals and their cavitation-damage resistance, high-frequency fatigue tests at 14.2 kcs were conducted using a magnetostriction oscillator. Utilizing Morrow’s theory, it has been shown that fatigue at this frequency can be quantitatively represented if a 15 percent reduction in static strain-hardening factor is made. This result shows that the strain-rate effects are relatively small (for the metals investigated) when plastic-strain energy is used as a criterion. Another result revealed by this study is the influence of corrosion on high-frequency fatigue and cavitation-damage resistance. Present experiments show that fatigue strength can be reduced significantly for SAE 1020 steel in 3 percent NaCl solution even at high frequencies, thus confirming earlier speculations on this aspect.

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On Testing Materials for Cavitation Damage Resistance

Journal of Ship Research ◽

10.5957/jsr.1964.8.5.39 ◽

1964 ◽

Vol 8 (05) ◽

pp. 39-56

Author(s):

A. Thiruvengadam ◽

H. S. Preiser

Keyword(s):

Experimental Data ◽

Steady State ◽

Experimental Results ◽

Time Dependent ◽

Testing Time ◽

Average Depth ◽

Damage Resistance ◽

Cavitation Damage ◽

Damage Rate

Recent experiments with a magnetostriction apparatus show that cavitation-damage rate is time dependent. This is confirmed by an analysis of the experimental data obtained in various earlier investigations. There are four zones of damage rate with respect to testing time; namely, (a) incubation, (b) accumulation, (c) attenuation, and (d) steady state. In the fourth, or steady-state zone, the damage rate varies as the square of the amplitude of oscillation within the range tested for water at 80 F. The damage rate increases with frequency and then decreases with increasing frequency. The depth of liquid in the beaker, the beaker diameter and the depth of immersion of the specimen do not seem to affect the damage rate substantially. The average depth of erosion is independent of the diameter of the specimen. Based on these experimental results, certain recommendations are made for testing materials for cavitation damage resistance.

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