Abstract
The purpose of this study is to examine the microstructure and micromechanical properties of pulsed-laser irradiated stainless steel. The laser marking was conducted for AISI 304 and AISI 316 stainless steel samples through a Nd:YAG (1064 nm) laser. The influence of process parameters such as the pulse repetition rate and scanning speed have been considered. The microstructures of obtained samples were analyzed using confocal optical microscopy (COM). The continuous stiffness measurements (CSM) technique was applied for nanoindentional hardness and elastic modulus determination. The phase compositions of obtained specimens were characterized by X-ray diffraction (XRD) and confirmed by Raman spectroscopy. The results revealed that surface roughness is directly related to overlapping distance and the energy provided by a single pulse. The hardness of irradiated samples changes significantly with the indentation depth. The instrumental hardness HIT and elastic modulus EIT drop sharply with the rise of the indentation depth. Thus, the hardness enhancement can be observed as the indentation depth varies between 100–1000 nm for all exanimated samples. The maximum values of HIT and EIT were evaluated for the region of small depths (100–200 nm). The XRD results reveal the presence of iron and chromium oxides due to irradiation, which indicates a surface hardening effect.
Highlights
Laser surface treatment has become one of the most popular techniques to enhance metallic materials’ surface functional properties, such as optical properties and corrosion resistance, as well as micromechanical properties like wear and microhardness
The laser surface melting (LSM) processing and other continuous laser irradiation techniques find a lot of applications [7,8,9], the pulsed laser modification technique becomes very promising
The aim of this study is to investigate the microstructure and micromechanical properties of commonly used stainless steel, i.e., AISI 304 and 316, after Nd:YAG (1064 nm) pulsed laser surface modification
Summary
Laser surface treatment has become one of the most popular techniques to enhance metallic materials’ surface functional properties, such as optical properties (color marking) and corrosion resistance, as well as micromechanical properties like wear and microhardness. It has commonly been assumed that surface treatment such as laser engraving or laser marking increase the lifetime and durability of proceeded components by changing their surface morphology, chemical composition and microstructure [12] It is achieved by means of short pulsed laser beams’ interaction with the material surface, and results in rapid phase and microstructure modification, mainly due to fast heating, melting, evaporating and solidification [12]. The aim of this study is to investigate the microstructure and micromechanical properties of commonly used stainless steel, i.e., AISI 304 and 316, after Nd:YAG (1064 nm) pulsed laser surface modification. The paper covers in detail how the process parameters affects the phase composition and different morphology formation, resulting in hardness and elastic modulus enhancement
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