Microstructure of TIG Melted Composite Coating on Steel Produced Using 1.0 and 1.5 mg/mm² TiC at an Energy Input of 2640 J/mm

Abstract

Surface modification by reinforcing ceramic particulates can give protection against wear and corrosion of metal. In this work, two different amounts of TiC powder of nominal size 45 to 100 µm were embedded on AISI 4340 steel surfaces by melting under a Tungsten Inert Gas (TIG) welding torch with an energy input of 2640 J/mm. The microstructure, geometry and hardness of the single track composite layers were investigated. The resolidified melt tracks were hemispherical in shape. With increasing TiC content, the melt dimensions reduced a little but the microstructure had a remarkable change. The track with 1.5 mg/mm2 TiC gave more un-melted TiC, partially melted TiC and agglomeration of ceramic particulates while the 1.0 mg/mm2 track dissolved most TiC particulates and precipitated carbides in the form of dendrite, globular and flower type particles; dendrites are almost absent in the 1.5 mg/mm2 track. A reduced TiC addition created more fluid melt which accelerated dissolution of TiC and that caused more carbide precipitation in the 1.0 mg/mm2 track compared to that with 1.5 mg/mm2 track. The 1.0 mg/mm2 track produced lower hardness of 1065 Hv compared to 1350 Hv for the 1.5 mg/mm2 track.

Overlapping tracks processed by TIG melting TiC preplaced powder on low alloy steel surfaces

“…These types of TiC distribution and segregation have also been reported in laser processed MMC coatings on titanium surfaces 7 and TIG torch processed coatings on titanium and steel surfaces. 21,27,[32][33][34][35] TiC precipitates of globular, cubic and flower morphologies were seen in many overlapping tracks, but were not uniformly distributed in the melt microstructures. Similar morphologies of TiC precipitates were also reported in single track composite coatings.…”

Synthetization of TiC surface hardening using TIG melting technique - The effect of working distance

“…Altering working distances in favour to have less or more melt involved no additional cost. Our experimental work showed that fusing the TIG arc at certain heat input of 1 mm working distance is limited to give dissolution of the TiC on the AISI 4340 low alloy steel substrate [9]. This work delivers information of melt pool sizes with regards to their HAZ, defects, microstructural features, and microhardness from used working distances at 0.5 mm and 1.5 mm.…”

Melting of SiC powders preplaced duplex stainless steel using TIG welding

“…Minitab 17 software was used to determine the no. of experiments to be conducted with the predetermined variables and their levels [5]. The optimum setting is the parameter combination, which has the highest S/N ratio [7].…”

“…This is because of high heat input resulted higher temperature of melt during TIG welding. This higher temperature melt has lower solidification rate which assists the melt to move towards the substrate thus producing larger melt pool [5].…”

“…Surface melting method is used because of its ability to eliminate interfacial incompatibility by creating thermodynamically stable reinforcements based on their nucleation from the substrate material. Idris et al [5] investigated the TiC composite coating on AISI 4340 using TIG torch method. Other finding by Adeleke et al [3] studied the Fe-C-Si coatings on CP-Ti melted under TIG torch techniques.…”