Energy-Based Water Droplet Impact Erosion Studies of Laser-Treated Austenitic and Martensitic Steels and their Applications

What is it about?

While conducting WDIE tests, the test conditions such as testing medium, BL growth, Vd / V ratio, Re, We, α, and β should be given due considerations. In absence of a medium, the water droplets are not subjected to sudden inertial and centrifugal forces and BL phenomenon does not exist. It is observed from the round test specimens that the WDIE damages are occurring near LE towards suction side where BL is attached and pressure gradients are high. The attached BL provides a cushion to impinging water droplets thereby helping in minimizing their excessive WDIE damages. The WDIE damage patterns of the test specimens are similar to those of LPST rotor blades. This is because of similarities in their KEfd variation around their surfaces. The WDIEr of a material appears to be proportional to the product of KEd and KEfd. Based upon this product, the WDIEr of different materials received from different laboratories, can be compared. The Hadfield’s‘AS’ specimens have performed very well in WDIE. This is because of its work hardening ability. After WDIE testing of 6h/3.42 x 106 WDI, the micro hardness of its top surface has increased more than twice which has resulted in improved MUR and resistance to WDIE. The performance of Hadfield’s‘LH’ specimens has deteriorated, may be because of finer cracks which have widened during WDIE testing. These cracks appear to be deep inside, resulting in quick removal. Its incubation period has also decreased drastically. The improved resistance to WDIE of X20Cr13‘LH’ specimens is because of increased martensitic phase, resulting in increased micro hardness and MUR. It has also extended its incubation period. HPDL treated X20Cr13 stainless steel can work as an excellent WDIE resistant shield. It has already replaced flame hardening of LPST blades. In case of helicopter rotor blades, it can be used in the form of replaceable caps near outboard blade tips where WDIE damages are severe. Hadfield’s steel being economical, can find applications in areas where WDIE is not that severe such as LP bypass valves, steam carrying pipe lines and bends.

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