Minimization of Porosity in E11018-G Low-Alloyed Steel Processed by Laser Powder Directed Energy Deposition

Abstract

Laser powder directed energy deposition (LP-DED) has emerged as a promising technology for the resurfacing and repair of components, offering a potential alternative to conventional welding techniques. The objective of this study is to examine the LP-DED processability window for the rail repair alloy E11018-G. The E11018-G powder, produced via gas atomization, is characterized and deposited onto C45 steel substrates. Following the optimization of LP-DED process parameters, the investigation is extended to evaluate external factors influencing porosity, including powder porosity, powder moisture, ambient humidity, and the application of laser remelting. The results present the processability window for E11018-G and identify powder porosity, originating from the gas atomization process, as the primary contributor to porosity in the LP-DED deposits. By systematically adjusting process parameters and external factors, internal porosity in LP-DED specimens is reduced from 0.7% to 0.04%. Microstructural analysis of the additively manufactured material reveals a predominantly fine-grain ferritic structure with an average hardness of 235–250 HV_0.3. These findings confirm the processability of the E11018-G material using LP-DED and highlight the critical influence of atomization gas on the LP-DED deposits.