Journal of Emerging Trends in Engineering and Applied Sciences: Research Areas

Article Title: Pre-Cooling Treatment Impact on Mechanical Properties and Fracture Type of used and welded Hadfield steel
by E. Curiel- Reyna, I. Rojas-Rodriguez, J. Teran, A. Lara-Guevara, A. Del Real, R. Velazquez Hernandez, and M. E. Rodriguez-Garcia

Abstract:
It is well known that the most important Hadfield steel mechanical properties are high resistance to wear and high toughness. When Hadfield steel pieces fail, it is necessary an effective welding repair method to keep mechanical properties. Different pre-cooling treatments were analyzed to evaluate their feasibility on mechanical properties and metallurgical changes of welded Hadfield steel. The objective of this study is to ascertain the pre-cooling effect on microstructure properties, hardness, stress-strength and, fracture type in the heat affected zone of used Hadfield steel after being pre-cooled and welded in order to improve the welding repair process. Samples were pre-cooled at 0 oC, -30 oC and -60 oC and then arc welded. Vickers Micro-hardness and tension test at room temperature were used to evaluate mechanical properties, as well as SEM to inspect the metallurgical microstructure and the fracture type after the tensile strength test to identify the effect of welding process conditions. Pre-cooling produced a grain micro-hardness increase. Stress-strain curves of pre-cooled samples showed a mechanical property decrease at the heat affected zone. Maximum strength, yield strength limit and material deformation resulted lower in pre-cooled and welded samples than in homogenized samples. Fractures of pre-cooled and welded samples resulted of the fragile type; in as much as predominant was the cleavage condition. Grains showed no deformities but the type of fracture, the pre-cooling and inter-granular zone discontinuities weakened the mechanical resistance. Therefore, discontinuities in austenite grain and grain boundary at the heat affected zone produced a highly fragile material behavior without any important plastic deformation.

Keywords: pre-cooling temperature, Hadfield steel, heat affected zone, high manganese, welding repair, mechanical properties, fracture type

Download full paper