scholarly journals Effect of Nb Content on the Microstructure and Wear Resistance of Fe-12Cr-xNb-4C Coatings Prepared by Plasma-Transferred Arc Welding

Coatings ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 585
Author(s):  
Lin Zong ◽  
Yinglong Zhao ◽  
Shiteng Long ◽  
Ning Guo

The Fe-Cr-C coatings with different levels of Nb addition were prepared on carbon steel by a plasma transferred arc (PTA) weld-surfacing process and their microstructure and properties were investigated. As the Nb content increases from 8.96% to 12.55%, the coating gradually changes from a hypereutectic structure (martensite, austenite matrix, primary NbC and eutectic γ+M7C3) to a near eutectic structure (γ+M7C3 and NbC) and finally a hypoeutectic structure (primary γ, γ+M7C3 and NbC). As the Nb content increases, the hardness and wear resistance of the coating first increase and then decrease, which is closely related to the NbC volume fraction first increasing and then the NbC size coarsening. The Fe-Cr-C coating with 11.65% Nb balances the NbC content and size, and has the highest hardness and best wear resistance. As the Nb content increases further, the formation and aggregation of coarse NbC carbides in the coating results in high brittleness of the coating, which may cause the carbide particles to peel off the coating during the wear process, thereby reducing wear resistance.

Coatings ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 265 ◽  
Author(s):  
Lin Zong ◽  
Ning Guo ◽  
Rongguang Li ◽  
Hongbing Yu

The Fe-3Ti-xB-4C (x = 1.71, 3.42, 5.10, 6.85 wt. %) hardfacing alloys are deposited on the surface of a low-carbon steel by plasma transferred arc (PTA) weld-surfacing process. Microstructure, hardness and wear resistance have been investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), Rockwell hardness tester and abrasive wear testing machine, respectively. The results show that the microstructure in all alloys is composed of austenite, martensite, Fe23(C,B)6, Ti(C,B) and Fe2B. The volume fraction of eutectic borides and Ti(C,B) carbides increases with increasing B content. Many brittle bulk Fe2B phase arises when the boron content increases to 6.85%, which causes the formation of microcracks in the hardfacing layer. The microhardness of the hardfacing alloys is significantly improved with the B addition, however, the wear resistance of hardfacing alloys increases firstly and then decreases with increasing of B content. The hardfacing alloy with the 5.10% B content has the best wear resistance, which is attributed to high volume fraction of eutectic borides and fine Ti(C,B) particles distributed in the austenite and lath martensite matrix with high hardness and toughness. The formation of brittle bulk Fe2B particles in the hardfacing alloy with the 6.85% B leads to the fracture and spalling of hard phases during wear, thus, reducing the wear resistance.


2016 ◽  
Vol 25 ◽  
pp. 1305-1311 ◽  
Author(s):  
Mohammed Mohaideen Ferozhkhan ◽  
Muthukannan Duraiselvam ◽  
Kottaimathan Ganesh kumar ◽  
Rajanbabu Ravibharath

Author(s):  
H.-J. Kim ◽  
Y.J. Kim

Abstract Commercially available coating techniques such as "open arc" and "spray & fuse" methods were used to compare the microstructural development with the plasma transferred arc (PTA) coating process for the hardfacing of NiCrBSi and Stellite 6 alloys. Denser eutectic structure was observed in the case of PTA coated layers of the Stellite 6 alloys than those of open arc weld-surfacing process. The shape of both carbides and borides in the 16C alloy coated by PTA processing were also obtained to have coarse morphology of carbides and borides while the "spray & fused" layers show a needle shape with finer distributions. Possible thermal history during each coating process is discussed. Based on microstructural observation, the hardness, wear resistance, and corrosion behaviors are reported. As expected, the alloy properties are directly related to their constituents of microstructure.


Alloy Digest ◽  
1995 ◽  
Vol 44 (12) ◽  

Abstract COLMONOY No. 83 PTA is a nickel-base hard surfacing alloy containing tungsten carbide. The application method is plasma transferred arc and the application is designed to protect extrusion screws. This datasheet provides information on composition, physical properties, microstructure, hardness, tensile properties, and compressive strength. It also includes information on wear resistance as well as machining and powder metal forms. Filing Code: Ni-493. Producer or source: Wall Colmonoy Corporation.


Author(s):  
I. Kretschmer ◽  
P. Heimgartner ◽  
R. Polak ◽  
P.A. Kammer

Abstract Fusible Ni-B-Si alloys with a variety of alloy additions (Cr, Mo, Cu etc.) have been in service for many years as fused coatings with moderate corrosion resistance. Both gas- and water-atomised powders have been used with the spray and fuse and with the plasma transferred arc process to produce coatings. As the severity of corrosive industrial environments has increased, for example in waste burning boilers, existing alloys have not provided the desired service performance. This study was undertaken to develop a new family of alloys with improved corrosion resistance without sacrificing usability, wear resistance or cost effectiveness. A range of compositions was prepared and evaluated for deposition characteristic, microstructure, hardness, wear resistance and corrosion resistance in various media. The resulting alloy has an exceptional combination of wear and corrosion resistance in comparison to conventional alloys, when tested under comparable conditions.


2011 ◽  
Vol 462-463 ◽  
pp. 593-598 ◽  
Author(s):  
Hong Xia Deng ◽  
Hui Ji Shi ◽  
Seiji Tsuruoka ◽  
Hui Chen Yu ◽  
Bin Zhong

The Plasma transferred arc welding (PTAW) is widely used for hardfacing components exposed to severe conditions. Without post welding heat treatments, large tensile residual stresses remain in the hardfacing coating, which is detrimental. In this paper, a set of post welding heat treatments was evaluated for the heat-resistant steel substrate – Co-based alloy hardfacing coating system. Microstructural and mechanical properties, including the chemical phases of coating surface, the microstructure of coating surface, the Vickers hardness and the residual welding stress, were investigated before and after the heat treatments. Results revealed that during the heat treatments, some elements reprecipitated and the secondary carbide Cr23C6 was formed. After the treatments, a more regular structure and a higher Vickers hardness were obtained. Moreover, the tensile residual stresses in the coating decreased significantly. Therefore, it can be inferred that the post welding heat treatments employed in this paper were proper for this material system.


2018 ◽  
Vol 350 ◽  
pp. 480-487 ◽  
Author(s):  
Xinke Deng ◽  
Guojun Zhang ◽  
Tao Wang ◽  
Shuai Ren ◽  
Zhonglian Bai ◽  
...  

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