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The aim of this paper was to introduce the study on burr formation mechanism of nickel-based Hastelloy C-276 in the turning process. The process is monitored using a high-speed camera mounted on a computer numerical control (CNC) turning machine. The captured photographs show that the burr starts appearing on the edge of an uncut surface when the engagement with the chip-workpiece contact area is complete and increases accordingly during the process of hitting the cutting edge and causing chipping wear. The study shows that the initializing of chip burr formation can be divided into two stages: creating and mounting up. Creating of burr formation is characterized by the 'reaction of shear formation' of the cutting force on the edge of chip for an unmachined surface, while mounting up increasing in size and forcing the chip to change its direction shoots up the rake face. This edge of the burr will separate and re-attach with the burr edge again during mounting up, thus creating a chain web shape on the edge of the uncut surface and causing edge chipping. The results show that the approach angle has a significant effect on burr formation. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, it was indicated that the laser welding was well suitable to joining of thin Hastelloy C-276 sheet (0.5 mm thickness), and also the fine grain were observed in welding zone with invisible HAZ (heat affected zone). In addition, the smooth weld joint could be controlled by means of the laser parameter adjustment. On the other hand, it’s proposed that Ni–Cr–Co–Mo and austenite CFe15.1 cubic face-centered crystal structure should be existed in as-received and welding samples, as well as the cause of FWHM (Full Width at Half Maximum) widened and peak offset of joined samples were analyzed. [Copyright &y& Elsevier]

Abstract: This paper presents the results of a failure investigation carried out on a cast Hastelloy C-276 pump impeller that suffered general corrosion in 32% hydrochloric acid at ambient temperature in a chemical plant. Microscopic examination revealed that the attack was crystallographic in nature. The attack was more enhanced at the interdendritic arm spacing as well as the boundaries of columnar grains, resulting in deep grooves. Taking into consideration that the local temperature could reach up to 50°C in the summer months, Hastelloy C-276 was judged to be unsuitable material for applications involving 32% HCl. A search into a suitable alternative alloy did not provide a satisfactory answer. Therefore, rubber-lined pump impeller was considered the better alternative. [Copyright &y& Elsevier]

Abstract: Electron beam welding (EBW) technique is becoming popular in nuclear, chemical and aerospace industries due to its high penetration depth and fast cooling rate. Samples of Hastelloy C-276 have been welded by electron beam (EB). A scanning electron microscope (SEM) having the attachment of an energy dispersive system (EDS) has been employed to study the resulting microstructure and micro-eutectic phases. The microstructure of the molten zone (MZ) is found to be of fine lamellar type. The hardness of the MZ is found to be 35% higher compared to as-received alloy. The micro-eutectoids are rich in Mo and W. The X-ray diffraction patterns of the MZ show shifting of peaks towards higher angle compared to the diffraction pattern of the as-received alloy. Broadening of the peaks is also observed in the diffraction pattern of the MZ. Formation of the μ-phase was observed in the MZ after a tempering treatment at 950°C. [Copyright &y& Elsevier]