Surface remelting of 316 L   434 L sintered steel: microstructure and corrosion resistanceReportar como inadecuado




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Journal of Solid State Electrochemistry

, Volume 18, Issue 11, pp 2973–2981

First Online: 04 May 2014Received: 02 January 2014Revised: 21 February 2014Accepted: 17 April 2014

Abstract

This study presents arc surface remelting of three types of sintered stainless steels carried out in order to constitute a homogeneous microstructure in the surface layer which is free from open and interconnected porosity. The main aim of this treatment was to improve functional properties of the sinters analysed, especially their resistance to pitting corrosion. The sinters were obtained from powders of 316 L and 434 L steels. The PM austenitic-ferritic stainless steels are used mainly in the automotive industry, but their general application is still limited due to relatively poor corrosion properties when compared to casts or wrought components. This study used the gas tungsten arc welding GTAW process as a method of economical surface treatment. The effect of surface treatment was evaluated based on macro- and microstructural observations, energy-dispersive X-ray spectroscopy EDX analysis, X-ray phase analysis, measurements of surface roughness and electrochemical examinations. It was found that a cellular or mixed cellular and dendritic structure was formed in the remelted zone of the sinters after remelting. X-ray analysis demonstrated that application of remelting contributes to formation of the austenitic phase in the surface layer. The corrosion resistance of the remelted surface layers was evaluated using polarization tests in 0.5 M NaCl solution. It was found that arc surface remelted layers exhibit much better anticorrosive properties than sinters without surface treatment. Microstructural observations of the surface of specimens after electrochemical tests showed only a few single pits in the remelted layer, while the surface of initial sinters was much more corroded.

KeywordsSintered steel Surface treatment Pitting corrosion Electrochemical method  Download fulltext PDF



Autor: Agata Dudek - Agata Wronska - Lidia Adamczyk

Fuente: https://link.springer.com/







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