TY - JOUR

T1 - Effects of heat inputs on the structure of Ni-based amorphous composite coatings applied with laser cladding

AU - Li, R.

AU - Chen, Z.

AU - Gu, J.

AU - Wang, Y.

AU - Wu, M.

AU - Tian, Y.

PY - 2019/7/1

Y1 - 2019/7/1

N2 - In this paper, Ni-based amorphous composite coatings were fabricated under different heat inputs on a mild-steel substrate usinglaser cladding with coaxial powder feeding. The microstructure of the coating was studied using a scanning electron microscope(SEM), X-ray diffraction (XRD) and transmission electron microscope (TEM). The effects of the heat inputs on the amor- phous-phase forming ability of the Ni-based alloy was investigated systematically with experimental and numerical simulationmethods. The results show that there was no amorphous phase in the coating when the heat input was 131.3 J/mm. Theamorphous-phase fraction increased with a decrease in the laser-cladding heat inputs from 81.3 J/mm to 50.0 J/mm. Then a 3Dthermal finite-element (FE) model was built to simulate the temperature field of coaxial laser cladding at different heat inputsusing the element birth and death technique. Detailed 3D transient thermal analyses were performed on temperature-dependentmaterial properties. The proposed model was validated with the experimental results. It was found that a decrease in the heatinput leads to a lower high-temperature residence time and a higher cooling rate of the melted pool. Consequently, a low heatinput can be considered as a necessary condition for the formation of the amorphous phase during the laser-cladding process.

AB - In this paper, Ni-based amorphous composite coatings were fabricated under different heat inputs on a mild-steel substrate usinglaser cladding with coaxial powder feeding. The microstructure of the coating was studied using a scanning electron microscope(SEM), X-ray diffraction (XRD) and transmission electron microscope (TEM). The effects of the heat inputs on the amor- phous-phase forming ability of the Ni-based alloy was investigated systematically with experimental and numerical simulationmethods. The results show that there was no amorphous phase in the coating when the heat input was 131.3 J/mm. Theamorphous-phase fraction increased with a decrease in the laser-cladding heat inputs from 81.3 J/mm to 50.0 J/mm. Then a 3Dthermal finite-element (FE) model was built to simulate the temperature field of coaxial laser cladding at different heat inputsusing the element birth and death technique. Detailed 3D transient thermal analyses were performed on temperature-dependentmaterial properties. The proposed model was validated with the experimental results. It was found that a decrease in the heatinput leads to a lower high-temperature residence time and a higher cooling rate of the melted pool. Consequently, a low heatinput can be considered as a necessary condition for the formation of the amorphous phase during the laser-cladding process.

KW - laser cladding

KW - amorphous

KW - microstructure

KW - heat input

KW - simulation

U2 - 10.17222/mit.2018.241

DO - 10.17222/mit.2018.241

M3 - Journal article

VL - 53

SP - 521

EP - 526

JO - Materiali in Tehnologije

JF - Materiali in Tehnologije

IS - 4

ER -