Solid-state local micro-alloying of thick st37 steel plates with SiC powder using a modified friction hydro-pillar process

Abstract

Friction hydro-pillar processing is a solid-state process to repair cracks in thick plates, pipes, and vessels. In this study, this process is modified to be used as a solid-state micro-alloying process to make in-depth alloys in steel plates. Alloying is carried out mostly in the liquid phase which results in problems such as dendritic microstructure. Also, there are some restrictions regarding mechanical alloying such as long sintering time. In the present study, The SiC powder was added to St37 steel. A cartridge was drilled in the center of the stud to place the alloying powder. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses were used to investigate the powder distribution. Although several agglomerated zones were detected, the results indicate a uniform distribution of the powder. The results also suggest that the SiC was dissolved during the process. Optical microscopic was also utilized to investigate the phase transformation during the process. Due to the high temperatures and strain rate experienced by the stud and the base material during the process, significant changes occur including the formation of Widmanstätten structure. The micro-hardness and tensile properties of the samples were also tested to evaluate their mechanical properties. The highest achieved average micro-hardness and ultimate tensile strength were 395.8 HV and 511.2 MPa, respectively.