Cavitation Erosion Resistance Of Duplex Stainless Steel And Co Alloy Coating On 304 Stainless Steel By TIG Cladding

Cavitation erosion is a damage process consisting of the repeated nucleation, growth, and violent collapse of bubbles in liquid. It rapidly reduced the lifetime of marine propeller and turbine blades. In order to decrease the damage of cavitation erosion, a series of cavitation erosion resistance materials have been developed, such as cobalt base alloy and copper base shape memory alloy. But all of these alloys are very expensive, and it's difficult to be promoted. In order to improve the properties of hydraulic machinery, a cavitation erosion resistance cladding layer was synthesized on 304 stainless steel by TIG cladding technology.The Cr-Ni-Mo austenitic-ferritic stainless steel and new Co alloy were cladding on 304 stainless steel by TIG technology. The cavitation erosion experiment was carried out in tap water by using an ultrasonic-induced cavitation erosion facility, and the cavitation erosion behavior of these materials was systemically tested and analyzed by OM, SEM, XRD, microhardness tester and roughness method. The effect of TIG surface remelting process on cavitation erosion resistance of Co alloy was also studied.As shown in results, the TIG cladding layer of Cr-Ni-Mo austenitic-ferritic stainless steel was consist of coarse dendrite grains. For the cladding surface had no second phase, and the cracks extended easily in the cladding layers. Such structure accelerated the process of cavitation, and the cumulative mass loss of TIG cladding Cr-Ni-Mo austenitic-ferritic stainless steel sample was 2 times of Cr-Ni-Mo austenitic-ferritic stainless steel. Both of the Co alloy of TIG cladding layer and TIG surface remelting layer were build up by reticular formation, and the reticular were consist of boride and Co intermetallic compounds. The TIG remelting layer has excellent dispersion strengthening effect and the mechanical properties of materials. During the cavitation erosion, the continuous pulse induced martensitic transformation. And the phase transition absorbed lots of impact energy, then the martensite fracture distorted. As shown in the experiment, both TIG cladding Co alloy layer and TIG remelting Co alloy layer have excellent cavitation erosion resistance, and the remelting layer was slightly better.