1 Key Laboratory of Automobile Materials, Ministry of Education, College of Materials Science and Engineering, Jilin University, Changchun 130022, China 2 School of Materials Science and Engineering, Dalian Jiaotong University, Dalian 116028, China 3 School of Materials Science and Engineering, Tongji University, Shanghai 200092, China 4 School of Electrical Engineering, Northeast Dianli University, Jilin 132012, China
Cite this article:
Hongyong XU,Wenquan WANG,Shiming HUANG,Xiangxia CHENG,Meixuan REN. MICROSTRUCTURES AND PROPERTIES OF Ni-BASEDWEAR RESISTANT LAYERS REINFORCED BYTiC GENERATED FROM IN SITU PLASMASPRAY WELDING. Acta Metall Sin, 2016, 52(11): 1423-1431.
Generally, wear is one of the main failure mechanisms for mold steel. The heavy financial loss will often occur if molds are out of service due to their hard manufacturing process and high cost of metal materials. Therefore, mold repairing is urgent and critical if they fail to function. Ni-matrix wear resistant composited layers reinforced by TiC generated from in situ plasma spray welding NiCrBSi+Ti powders were prepared. The analysis instruments of OM, SEM, XRD and EDS were used to study the microstructural characterization, phase identification and chemical compositions of the layers. And the microhardness and wear resistance were tested using Vickers hardness tester and abrasion tester, respectively. The investigations demonstrated that the layers were mainly composed of basic phases (γ-Ni+β1-Ni3Si) with eutectic features and hypereutectoid (α-Fe+FeNi3) structures, in which hard phases M7C3 and M23C6 were embedded in the matrix. The phase CrB was distributed uniformly in the layers. One part of TiC generated from in situ reaction acted as the nucleation of the chromium compounds precipitates M7C3 and M23C6. The other part of TiC was also distributed in the base with the fine particles (<1 μm) and even bigger size (>1 μm). Ti percentage rising, the microstructures of plasma spray welding layers were refined and the phase M23C6 increased while M7C3 decreased. When the Ti addition reached 6%, the layers had better performance with microhardness of 800 HV0.5. The wear mass loss of layers was 14.5 mg, which were more than 2 times of NiCrBSi layer.
Fig.1 SEM images and EDS analyses of NiCrBSi (a) and Ti (b) powders
Point
Atomic fraction / %
Phase
C
Cr
Ni
Fe
Si
A
30.96
36.38
3.88
28.32
0.46
(Cr, Fe)7C3
B
13.51
32.82
9.22
43.51
0.94
(Fe, Cr)23C6
C
10.17
83.93
1.06
4.85
-
Cr23C6
D
37.71
39.24
7.10
15.95
-
(Cr, Fe)7C3
E
26.71
66.62
-
6.67
-
Cr7C3
F
2.57
4.73
59.53
24.96
8.32
FeNi3
G
6.32
3.36
63.33
10.31
16.68
(γ-Ni+β1-Ni3Si)
Table 1 EDS analyses of different points in Fig.3
Fig.2 XRD spectra of NiCrBSi powders (a) and No.1 surfacing layer (b)
Fig.3 SEM images and EDS analyses of No.1 surfacing layer (a) SEM image of interface (b) EDS analysis along the line in Fig.3a(c) SEM image of middle (d) EDS mapping analyses of Fig.3c
Fig.4 XRD spectra of No.2~No.6 surfacing layers
Point
Atomic fraction / %
Phase
C
Ti
Cr
Ni
Fe
Si
Mo
V
H
25.54
1.03
4.63
9.33
55.28
2.93
0.61
0.65
α-Fe
I
13.37
0.42
28.27
10.90
47.04
-
-
-
(Fe, Cr)23C6
J
32.32
0.51
23.20
5.54
38.43
-
-
-
(Fe, Cr)7C3
K
18.59
4.87
67.51
4.54
4.48
-
-
-
Cr23C6
L
11.75
2.67
5.24
43.78
29.63
6.93
-
-
(α-Fe+FeNi3)
M
8.69
3.56
3.42
50.03
16.25
18.05
-
-
(γ-Ni+β1-Ni3Si)
N
29.37
53.35
5.43
6.82
5.03
-
-
-
TiC
Table 2 EDS analyses of different points in Fig.5
Fig.5 SEM images and EDS analyses of No.2 surfacing layer(a) SEM image of interface (b) SEM image of bottom(c) SEM image and Ti EDS mapping analysis (inset) of middle(d) SEM image and Ti EDS mapping analysis (inset) of top(e) partial magnification SEM image and Ti EDS mapping analysis (inset) of top layer(f) EDS of point N in Fig.5e
Fig.6 SEM image of No.4 surfacing layer (a) and EDS analyses along line in Fig.6a (b)
Fig.7 SEM images and EDS mapping analyses (insets) of No.3 (a), No.4 (b), No.5 (c) and No.6 (d) surfacing layers in the middle
Fig.8 Microhardness (a) and wear mass loss (b) of different surfacing layers
Fig.9 Microstructures of substrate material H13 (a) and No.1 (b), No.3 (c) and No.6 (d) surfacing layers after wear test
[1]
Kulkarni K, Srivastava A, Shivpuri R, Bhattacharya R, Dixit S, Bhat D.Surf Coat Technol, 2002; 149: 171
[2]
Srivastava A, Joshi V, Shivpuri R.Wear, 2004; 256: 38
[3]
Jacobsen S D, Hinrichs R, Baumvol I J R, Castellano G, Vasconcellos M A Z.Surf Coat Technol, 2015; 270: 266
[4]
Lei Y W, Sun R L, Tang Y, Niu W.Opt Laser Eng, 2015; 66: 181
[5]
Wang D, Li H, Yang H, Ma J, Li G.Chin J Aeronaut, 2014; 27: 1002
