Investigation of ER۴۳۰ Buffer Layer Effects on Chromium Dilution, Mechanical Properties, and Microstructure in ER۴۱۰NiMo Weld Overlay on Carbon Steel

Weld overlay using martensitic ER۴۱۰NiMo filler metal on carbon steels is a common method to improve the wear and corrosion resistance of valve's trim in oil and gas industries. However, severe dilution at the fusion boundary and uncontrolled mixing of the molten weld metal with the A۱۰۵ base steel can lead to chromium loss, formation of low-chromium martensite, and a reduction in final hardness. In this study, to control dilution and enhance the metallurgical behavior of the overlay, the effect of employing a ferritic ER۴۳۰ buffer layer in ER۴۱۰NiMo weld overlay on A۱۰۵ steel was investigated. For this purpose, two configurations were prepared: a sample without a buffer layer (two consecutive passes of ER۴۱۰NiMo on A۱۰۵) and a sample with a buffer layer (first pass ER۴۳۰ followed by a final pass of ER۴۱۰NiMo), both deposited under identical thermal conditions and in accordance with API RP ۵۸۲ guidelines. Macrographic examination, optical metallography, SEM analysis, line-scan EDS, XRF, and micro-Vickers hardness testing showed that the presence of the ER۴۳۰ buffer layer reduced penetration depth and fusion zone width, prevented severe chromium depletion in the dilution zone, refined and homogenized the martensitic structure of the final overlay, and increased the hardness and its uniformity across the cladding thickness. Therefore, the use of an ER۴۳۰ buffer layer in ER۴۱۰NiMo weld overlay can serve as an effective practical approach to enhance the performance of carbon-steel valve's trim operating under severe service conditions.

کلیدواژه ها:

Weld overlay ، Chromium dilution ، ER۴۱۰NiMo filler metal ، A۱۰۵ carbon steel ، ER۴۳۰ buffer layer