Influence of Cooling Rate on the Structure of Heat Affected Zone After Welding a High Manganese Steel

Abstract

In this paper, the influence of the cooling rate on the structural properties, hardness, and defect formations of the heat affected zone (HAZ) of Hadfield steels was studied. The chemical composition of the samples used in this study was determined using X-ray fluorescence. The microhardness was measured using the Vickers hardness test. X-ray diffraction was used to study the influence of the heat treatment on the crystalline quality of the austenitic grain. The X-ray FWHM of the samples was used to study the evolution of the crystalline quality. And finally, electronic microscopy images were used to study the evolution of defects, especially voids, microvoids, carbide precipitates, and microfractures caused by the cooling rates on the heat affected zone. The homogenized samples exhibited residual stress and lower crystalline quality. The results indicate that when the cooling rate decreases, the crystalline quality, grain hardness, and grain microhardness increases. The sample cooled in oil showed changes in void formation when compared to the homogenized sample. In the case of air cooling, there were increments in size of the voids and also microfissures and carbide precipitation. Finally, for the furnace-cooled sample, the existence of microfissures along with fractures was evident, and a significant carbide precipitation exhibiting different morphology was also observed in this case.

Effect of Carbide Precipitation on the Structure and Hardness in the Heat-Affected Zone of Hadfield Steel After Post-Cooling Treatments

“…However, the phase identification of this precipitate has been not reported. The localization of the carbides precipitate is present into the fracture or also can be associated with the initial fracture process in this kind of steel [5]. If we compare Figs.…”

“…The measurement of the microhardness of the samples postcooling welded, in grain boundary and mass of the grains of Austenite next to the fusion line in the heat-affected zone presented a significant difference against the hardness of the homogenized sample. Due to the precipitation of carbides in the grain boundary and in the mass of the grains of Austenite, during the continuous treatments of cooling, the hardness of the material was increased, besides the presence of cracks, fissures, and microfissures (5).…”

“…In the case of air cooling, there were increments in void sizes, microfissures, and carbide precipitation. Finally, for the furnace-cooled sample, the presence of microfissures and fractures was evident, and a significant carbide precipitation exhibiting different morphology was observed [5].…”

“…Recently, Curiel et al [5] studied the evolution of defects, particularly voids, microvoids, carbide precipitates, and microfractures caused by the cooling rates on the heataffected zone. According to their results, the homogenized samples exhibited residual stress and lower crystalline quality.…”

Structure of High-Carbon Steel After Welding With Rapid Cooling

“…This will allow obtaining welding joints with higher wear resistance. Currently rapid cooling is used at most as technique to improve mechanical properties of HAZ formed during friction stir welding of Al-based alloys [23,24], Fe-based alloys with different carbon content [25,26,27]. Some techniques like explosion welding or laser welding involve rapid cooling without any special efforts [28,29], although even during laser welding especially accelerated cooling is sometimes necessary [30].…”