# Microstructure and Mechanical Properties of 1080 Plain Carbon Steel Fabricated by Laser Powder Bed Fusion Under High-Density Printing Parameters

## TL;DR

This paper shows how laser additive manufacturing can produce high-strength carbon steel without complex alloying or heat treatments.

## Contribution

A novel approach to enhancing mechanical properties of 1080 carbon steel through precise control of LPBF process parameters.

## Key findings

- High-density 1080 carbon steel with UTS of 1745.4 MPa was fabricated using LPBF.
- Martensite content decreases with increasing volumetric energy density (VED).
- Mechanical properties degrade significantly as VED increases beyond 92.59 J/mm3.

## Abstract

For structural metallic materials, performance enhancement has traditionally relied on complex adjustments of chemical composition and heat treatment processes. However, these approaches are complex, costly, and lack sustainability. Metal additive manufacturing (AM) has unique cooling characteristics, providing it with a distinctive approach. In this study, laser powder bed fusion (LPBF) technology was used to prepare high-performance 1080 carbon steel. The study selected three groups of process parameters (VED = 92.59 J/mm3) with high density (relative density > 98%) and achieved excellent mechanical properties: the ultimate tensile strength (UTS), yield strength (YS), and elongation (EL) reach 1745.4 MPa, 1455.13 MPa, and 6.77% respectively. The effects of process parameters on microstructure and mechanical properties were investigated. It is found all specimens exhibited a characteristic martensitic needle-like grain morphology without significant crystallographic texture. The microstructure displayed substantial changes as VED varied, with martensite content progressively decreasing with increasing VED. Correspondingly, as the VED increases from 92.59 J/mm3 to 225.69 J/mm3, the UTS, YS, and EL decrease by 39.0%, 36.1%, and 3.4%, respectively. This work demonstrates the feasibility of achieving high-performance metallic components by precisely controlling additive manufacturing process parameters to manipulate the microstructure of simple alloys, thereby eliminating the need for complex alloying or post-processing heat treatments.