Effect of interlayers on the microstructure and wear resistance of Stellite 6 coatings deposited on AISI 420 stainless steel by GTAW technique

The role of metal matrix composites (MMCs) has gained huge momentum in various researches as well as in industrial applications due to their high stiffness and higher strength to weight ratio. It helps in achieving enormous weight reduction without compromising the strength of the material. In this study, a novel attempt was made to fabricate MMCs with martensitic stainless steel as matrix and titanium diboride (TiB 2 ) as reinforcement. The AISI 420 matrix with different weight percentages (1%, 2%, and 4%) of TiB 2 reinforcement was fabricated by vacuum induction melting technique (VIM). The aim of this study was to analyze the influence of TiB 2 particle addition on the mechanical and tribological properties of AISI 420 composites. X-ray diffraction studies revealed the presence of TiB 2 phase in the composite along with peak shifting and broadening of the steel matrix due to induced strain. Optical microscopy showed the distribution of TiB 2 particles in the matrix along with a significant amount of grain refinement of the composite due to the addition of TiB 2 . Microhardness results showed that the presence of TiB 2 improved the hardness with AISI 420/4%TiB 2 composite possessing the maximum hardness. Tensile test results indicated a significant improvement in the ultimate tensile and yield strength of the composite with the addition of TiB 2 . The wear tests were carried out on a pin on disc tribometer for various loads at a different sliding distance for steady sliding velocity. The dispersion of TiB 2 particle helped in achieving better wear resistance of the composites. Wear surface morphology was carried out to explore the wear mechanisms. Among the various wear mechanisms, abrasion and oxidation phenomena dominated in the composites. Taguchi optimization technique predicted that wt% of TiB 2 and applied load as influencing factors on the wear rate of the material.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigation on mechanical and tribological behaviour of titanium diboride reinforced martensitic stainless steel

Sadhasivam

Mohan²,

Sankaranarayanan

et al. 2020

“…Wear-resistant Stellite coatings are applied by various methods such as thermal spraying [9], gas tungsten arc welding (GTAW) [10], plasma transferred arc (PTA) [11], flame spraying [12], and laser metal deposition (LMD) [13]. LMD is a laser cladding approach which can be used to fabricate functional, three-dimensional components.…”

Section: Introductionmentioning

confidence: 99%

Effects of lateral and vertical ultrasonic vibrations on the microstructure and microhardness of Stellite-6 coating deposited on Inconel 718 superalloy through laser metal deposition

Hosseini-Tayeb¹,

Rafiaei

2020

In this research work, Stellite-6 was deposited on an Inconel 718 substrate via laser metal deposition (LMD) process. Lateral and vertical ultrasonic vibrations were applied during the LMD process at 150 W and 250 W to achieve improved properties. The resultant coatings were evaluated by scanning electron microscopy (SEM) equipped with an energy dispersive spectroscopy (EDS) analyzer and optical microscopy. Also, the microhardness values of two samples (without vibration and with vertical vibration) were measured. The results showed that applying ultrasonic vertical vibrations led to significant changes in the microstructure of the coatings and the coating/substrate interface i.e. a better distribution of alloying elements of the coating was achieved, the number of the secondary arms increased, and the porosity percentage decreased significantly. Moreover, the microhardness value in the sample synthesized at 150 W and under vertical vibrations were higher than that in the sample produced without vibrations.

“…As a result, it is widely used in valves industries, power plants, nuclear reactors etc Literature review indicates that this material because of its industrial importance has caught the attention of various researchers. Stellite superalloy hardfacing over various industrially active substrate materials has been reported to be carried out using various weld overlaying processes like GTAW, GMAW, Plasma transferred arc etc [5][6][7][8][9][10][11][12]. Laser welding for hardfacing using Stellite 6 has also been applied covering a range of aspects including parametric optimization, wear characterization of clads etc [13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Investigations on high temperature wear and metallurgical characteristics of Stellite 6 GTA (Gas Tungsten Arc) weld claddings

Prakash

Shahi

2020

Stellite 6, a cobalt based superalloy was deposited on mild steel AISI 1020 using Gas tungsten arc welding (GTAW) process. The claddings were overlaid in four conditions viz. single layer cladding, double layer cladding, single layer cladding with remelting and double layer cladding with remelting, where remelting of the topmost layer was carried out using autogeneous GTA arc itself. The chemical composition, microstructure, wear mechanism and phase composition of the substrate and coatings were characterized by spectroscopy, optical microscopy, scanning electron microscopy, energy dispersive spectroscopy and x-ray diffraction. The hardness and wear characteristics of different cladded samples were measured using microhardness tester and pin on disc high temperature tribometer respectively. The results show that remelting of Stellite 6 clad layers resulted into microstructural modification that increased their hardness significantly which consequentially improved their wear performance. Oxidative layer formation that occurred at 300°C reduced frictional resistance which resulted into better wear performance of Stellite 6 clad pins. Further, a critical clad thickness was established based upon the wear performance of these claddings and it was observed that 5 mm Stellite clad thickness was sufficent enough to impart uniform wear behavior to these claddings when subjected to high temperature two body abrasive wear applications.