Influence of combined laser heat treatment and ultrasonic impact treatment on microstructure and corrosion behavior of AISI 1045 steel

This work aimed to study the influence of a laser heat treatment (LHT), ultrasonic impact treatment (UIT), and their combinations on the corrosion behavior of AISI 1045 carbon steel in saline solution. Microstructural features and phase state formed in the near-surface layers by LHT-induced transformations and UIT-induced plastic deformation were observed by optical microscopy, X-ray diffraction analysis, and transmission electron microscopy . The surface roughness, hardening intensity, and residual stresses were also analyzed. The results of the polarization experiments showed an essential increase of corrosion potential, corrosion current attenuation and increase in the protection efficiency of the passive film indicating a slowdown of the corrosion rate of the of 1045 steel specimens by the LHT and combined (UIT + LHT, LHT + UIT) techniques, while the single UIT process was less effective. In addition to the LHT-formed oxide layer, the following microstructural factors affect the enhanced corrosion resistance of 1045 steel: the lowered surface roughness, compressive residual stresses, the martensite formation instead of ferritic/pearlitic structure, an increase in the carbon content in the iron lattice due to cementite dissolution, refinement of the martensitic grains. The combined LHT + UIT process is concluded to be the most effective method providing the anti-corrosion performance of 1045 steel. •Laser heat treatment (LHT) and ultrasonic impact treatment (UIT) are applied to AISI 1045 steel.•Polarization behaviors are evaluated after LHT, UIT, UIT + LHT, and LHT + UIT processes.•Microstructure, phase composition, stress state, and corrosion parameters were studied.•Ultrafine martensitic structure and low roughness are produced by combined treatment.•The highest corrosion resistance enhancement was observed after the LHT + UIT process.