Development of a New High Strength Alloy from Low Alloy Steel Wire by Innovative Additional Cold Wire Feeding Used in Wire Arc Additive Manufacturing.

One of the most important features of the wire arc additive manufacturing (WAAM) is the ability to produce new structures from different materials. Thanks to the ease of application of the WAAM, more than one same or different material can be involved in the production process. Thus, WAAM has the potential to produce new material structures from raw wire metals with different chemical contents. In this study, it was aimed to produce a new alloy structure using WAAM. A novel cold wire feeding technique with an external system and gas metal arc welding (GMAW) process was implemented for the fabricating of a new alloy part. In the fabrication process, two different grades and ratios of ER70S-6 (90%) and 316LSi (10%) steel wires were used and melted simultaneously. The new alloy structure was successfully fabricated, and significant changes were found in the microstructure and tensile strength because of Cr and Ni elements transferred from the secondary wire (316LSi). In the microstructure of the new alloy, structures such as acicular ferrite, martensite, and bainite were observed. As a result of the different fabrication approach applied, a significant increase in tensile strength was found. The tensile strength of the new alloy structure exceeded 1000 MPa and almost 100% increase in strength was observed compared to single-material structures. In addition, the ductility of the produced structure was found to be sufficient. The study showed that new alloys with improved mechanical properties can be produced with the cold wire feeding + GMAW approach.