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The paper reports the influence of carburizing on the slurry erosion behavior of AISI 5117 steel using a whirling-arm rig. The microstructure and hardness profile of the surface layer of carburized steel were investigated. For characterizing the slurry damage process and for better understanding of material removal at different angles, scanning electron microscope (SEM) images at different locations on eroded surface using stepwise erosion combined with relocation SEM were presented. The study is also focused on studying the erosion wear resistance properties of AISI 5117 steel after carburizing at different impact angles. The tests were carried out with particle concentration of 1 wt. %, and the impact velocity of slurry stream was 15 m/s. Silica sand has a nominal size range of 250 – 355 μm was used as an erodent. The results showed that, carburizing process of steel increased the erosion resistance and hardness compared with untreated material for all impact angles. The erosion resistance of AISI 5117 steel increases by 75%, 61%, 33%, 10% at an impact angle of 30 deg, 45 deg, 60 deg, and 90 deg, respectively, as result of carburizing, i.e., the effectiveness of carburizing was the highest at low impact angles. Treated and untreated specimens behaved as ductile material, and the maximum mass loss appeared at impact angle of 45 deg. Plough grooves and cutting lips appeared for acute impact angle, but the material extrusions were for normal impact angles. The erosion traces were wider and deeper for untreated specimens comparing by the shallower and superficial ones for the carburized specimens. Chipping of the former impact sites by subsequent impact particles plays an important role in developing erosion.

A slurry whirling arm erosion test ring was constructed and a series of erosion tests and post-erosion analysis were carried out using a paint erosion indication technique. The pattern of the paint removal presented a highly visual and accelerated map for the erosion process and its behavior. Also, the erosion rate of paint removal was investigated under a number of erosion variables. It was observed that the rebounding of the erodent particles from the sample surface play an important role in developing erosion for this tester. The erosion pattern showed that the effect of the rebound particles depends on the impact velocity and impingement angle. It was also observed that the erosion behavior of paint as a function of impingement angle, impact velocity, and erosion time was similar to that reported in literature for engineering materials. The slurry whirling arm erosion tester seems to be promising for simulating the slurry process in real cases.

Cavitation erosion pits and their effects on erosion progression were investigated in detail for SUS 304 stainless steel, α+β brass (60/40), and pure aluminum (Al-99.999 and Al-99.92) by means of vibratory erosion. Two kinds of erosion pits were found on the specimen surfaces, one by microjet impact and the other by shockwave blow. Systematic observations of the feature of microjet-pits with the testing time showed that the sizes and shapes of microjet-pits did not change at all and such pits scarcely played an important role in developing the erosion. Moreover, the feature morphology of eroded surfaces, and dislodged particles and their large sizes revealed that microjet-pits had a limited effect on erosion and that the predominant failure was a fatigue process.