LIU Hong-xi*, ZENG Wei-hua, ZHANG Xiao-wei, WANG Chuan-qi, JIANG Ye-hua. Microstructures and properties of multiple-pass laser cladding Ni-based coatings on stainless steel surface[J]. Editorial Office of Optics and Precision Engineering, 2011,19(7): 1515-1523
LIU Hong-xi*, ZENG Wei-hua, ZHANG Xiao-wei, WANG Chuan-qi, JIANG Ye-hua. Microstructures and properties of multiple-pass laser cladding Ni-based coatings on stainless steel surface[J]. Editorial Office of Optics and Precision Engineering, 2011,19(7): 1515-1523 DOI: 10.3788/OPE.20111907.1515.
Microstructures and properties of multiple-pass laser cladding Ni-based coatings on stainless steel surface
In order to improve the surface hardness and corrosion resistance of stainless steel
single-pass and multi-pass lap laser cladding coatings of Ni25WC35 alloy powders were fabricated on a 1Cr18Ni9Ti substrate by a 6 kW transverse-flow CO
2
laser. The coatings were examined and tested for chemical compositions
microstructure features
phase structures
microhardness
corrosion behaviors and metallographies by the X-ray Diffraction (XRD)
Scanning Electronic Microscopy (SEM)
X-ray Energy Dispersive Analysis (EDAX)
microhardness tester
electrochemistry workstation and optical microscopy (OM)
respectively. The results show that some new harden phases are formed in the coating which consists of (Fe
Ni) solid solution and some compounds such as WC
W
2
C
CrNiFeC
FeW
3
C
Ni
2
Si
Fe
3
Ni
3
B
and these harden phases improve the hardness and corrosion resistance of the substrate effectively. OM observation displays that the microstructure of clad coating is homogeneous
compactness and forms a good metallurgical bonding layer with the substrate. Micro-hardness measurement exhibits that the surface hardness of treated sample is twice as large as that of substrate
and the highest hardness lies in the second pass cladding zone center of a double-pass coating sample and reaches 650HV. The electrochemical corrosion test in 5.0% NaCl saturated solution indicates that the maximum self-corrosion potential (
E
corr
) of clad coating sample changes from 630.90 mV to positive direction
and the lowest corrosion current density (
I
corr
) changes from 2.21 Acm
-2
to 0.55 Acm
-2
and decreases by 75.11%. Compared with the substrate
the corrosion resistance of laser cladding sample has been improved significantly
and the single pass cladding sample shows the best corrosion behavior.
关键词
Keywords
references
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