Abstract
In order to enhance the wear resistance of 304 stainless steel, a FeCrAlNbNi alloyed zone (AZ) was deposited on its surface using laser surface alloying technology, and the wear resistance of the AZ was investigated. The results found that the AZ had a dense and fine structure and no obvious defects, and the microstructure was mainly composed of equiaxed dendrites. A large amount of iron compounds and iron-based solid solutions in the AZ made the average microhardness of the AZ about 2.6 times higher than of the substrate. The friction and wear performance of the AZ at 25 °C, 200 °C, 400 °C and 600 °C better than that of the substrate. As far as the AZ was concerned, the abrasion resistance was the best under normal temperature environment. At 200 °C and 400 °C, due to the repeated extrusion and grinding of the friction pair, the oxide layer formed on the AZ surface was prone to microcracks and peeling off, which reduces the wear resistance. Especially at 400 °C, the formation and peeling speed of the oxide layer is accelerated, and the wear resistance is the lowest. However, when the temperature reached 600 °C, an Al2O3 layer was formed. And the Al2O3 has greater wear resistance to protect the AZ. At this time, the wear resistance was greatly improved compared to 200 °C and 400 °C. Therefore, as the temperature increased, the wear resistance of the AZ first decreased and then increased.
Highlights
304 stainless steel ball valve is an important pressure-bearing part
From the cross-sectional morphology of single-pass, it can be found that the alloyed zone (AZ) structure is compact and has no obvious defects, and the lower part of the AZ overlaps with the substrate
The microhardness of the heat-affected zone (HAZ) is reduced. This is because the cooling rate of the HAZ exceeds the critical cooling rate of hardening of the substrate, resulting in a martensitic structure [19]
Summary
304 stainless steel ball valve is an important pressure-bearing part. Because of its good sealing performance and simple operation, it has been widely used in oil and power pipeline systems. To optimize the wear performance of the material, many researchers use laser surface modification technology to prepare alloy layer on the surface of stainless steel, so that the wear resistance of its surface can achieve the desired effect. Ouyang et al [12] prepared Ni60-TiC-WS2 composite coating on the surface of 304 stainless steel using laser cladding surface modification technology, and the wear resistance of composite coatings and substrates and their related wear mechanisms have been systematically studied under different temperature environments. It was found that the alloy coating has good wear performance at high temperatures, which was mainly due to the formation of a dense protective oxide film during wear. This article uses laser alloying technology to deposit FeCrAlNbNi alloyed zone (AZ) on the surface of the 304 stainless steel substrate. Swcearn/nWing electron microscopy (SEM, S31460000N, HITACHI, Tokyo, Japan) and equWipavpeeldenegnthe/rgnymdispersive spectroscopy (EDS) we9r8e0–u1s0e2d0 to characterize the morphoLloagseyr ascnadnneilnegmsepnetedd/is(mtrimb/ust)ion of the AZ
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