Study of Microstructure and Mechanical Property Degradation of SA210 A1 Boiler Tube

Abstract

The comprehension of the microstructure change and mechanical property degradation are of particular importance for assessing the integrity of aging boiler tubes. This paper describes the investigation of microstructure evolution and mechanical property degradation of SA210 A1 steel used in an actual boiler condition. The investigation deals with visual inspection, chemical composition analysis, micrograph study using Energy Dispersive Spectroscopy-Scanning Electron Microscopy (EDS-SEM), tensile test and hardness test. The result showed that the prolonged operating period in the high temperature condition resulted in the reduction of the mechanical properties of the SA 210 A1 steel tube. The study also indicated the presence of the onset of the pearlite disintegration and coagulation, resulted from the microstructure degradation of the aged steel tube after the elevated temperature service in a boiler. It is advisable that the microstructure technique, i.e. metallurgical replica, should be added to the common on-site inspection to increase the effectiveness of the maintenance and maintain the availability of the steam generating units.

Erosion performance of direct-aged Al2O3-reinforced plasma-sprayed composite coatings at high-temperature conditions

“…The hardness, ductility and strength of the steel reduce after prolonged exposures to high temperatures. Peeratatsuwan1 and Chowwanonthapunya [5] in their studies compared the mechanical properties of used and un-used SA210 A1 steel tubes. Results were summarized in table 1 indicating the reduction in magnitude of the mechanical properties of failed tube.…”

“…The coatings composed of Ni-based super alloy powder offer protection against surface degradation due to their high creep strength and good oxidation Table 1. The comparison of mechanical properties of used and unused SA210 A1 tube [5]. resistance.…”

“…When further HT is applied to the as-sprayed coatings, it sets off the crystallisation of the amorphous phase, resulting in a significant enhancement of properties in the coatings. In addition, the produced coating's fracture toughness and microhardness are reduced as a result of pores, and microstructure cracks [5,6]. Consequently, the erosion resistance is negatively affected by the presence of such zones in the produced coating.…”