The feasibility study of the face-milling performance of hard-facing weld metal on JIS-S50C carbon steel was investigated on microstructure, chip characteristics, wear properties, and surface roughness. Discontinuous chips were found in all machining conditions. No buffering weld metal (No buffering layer, NBL) produces longer and thicker chips than that of the buffering weld metal (Buffering layer, BL). The flank wear of the cutting tool edge increases with the cutting length of the test specimen. The maximum wear of 850 mm was found in a wet condition of the NBL weld metal which is about 4 times higher than that of the base metal. High hardness value of the NBL weld metal produces a higher flank wear of the cutting tool edge than that of the BL weld metal. After comparing the wear of the cutting tool edge in wet and dry conditions, it was found that the dry condition exhibits a smaller flank wear than that of the wet condition. In the wet condition, more amount of coolant oil droplets cannot penetrate into the chip-tool interface and then provides an insufficient amount of lubricant in order to decrease the cutting temperature. Therefore wet condition produces severe wear of the cutting.

A shielded metal arc welding (SMAW) using various covered electrodes applied to produce a hard-faced weld metal on FC25 gray cast iron bare surface. It found that all welding parameters such as 3 electrode types and welding currents of 90-130 A were able to produce a sound weld metal without a defect that could deteriorate the joint strength. The white cast layer thickness that was formed at the interface between the weld metal and the base metal was increased when increasing in the welding current and the alloying element in the electrode. Impact strength tended to increase when the alloying element such as chromium (Cr), molybdenum (Mo), and manganese (Mn) was existed, and it showed the maximum impact strength when H600 electrode was applied. In a comparison of microstructure characteristics of the joints, the joint that showed the maximum impact strength had the formation of fine needle-like grain in the weld.

Hard-facing welding is one of the repairing methods for increasing hard metal on the agricultural machine part surfaces that caused by the wear mechanism. To this date, the investigation of an optimized welding process parameter that could produce high hardness and wear resistance of the hard-facing layer is still being developed and performed. This paper aims to study the effects of hard-facing welding layer on mechanical properties and microstructure of hard-facing weld metal on JIS-50C carbon steel. The summarized results are as follows: (a) an increase of hard-facing layer affected to increase the hardness of the layer, (b) the hardness of the welds showed a maximum hardness of about 750 HV at a top surface of 3rd welds layers with no-buffering layer and showed the minimum hardness of about 225 HV at a base metal, (c) microstructure investigation showed that the increase of the phase that contained higher chromium, molybdenum and manganese affected the increase of the hardness and the wear resistance of the weld metal, (d) The minimum mass loss of 0.2559 mg/m could be found when a welding current of 100A, non-buffering layer and 3 layers of hard-facing weld metal were applied, and (e) the buffering layer was able to produce a sound weld metal and might not be suited for the hard-facing welding of the medium carbon steel because it produced the dilution effect that deteriorated the mechanical properties of the weld metal.