Shear performance and failure mechanism of brass pins considering the temperature effect

Abstract

Premature shear failure of the brass pin often occurs during downhole tool operation, which has a serious impact on subsequent completion operations. Therefore, in order to explore its failure mechanism, the pin shear test considering temperature effect was designed and implemented in this paper to study the shear performance of different numbers of brass pins under different heating temperatures. Experimental data were fitted to obtain the continuous shear load–temperature curves for six, eight, and ten pins. The shear sections and the failure mechanism of the pins at different temperatures were observed by scanning electron microscopy. The results showed that the number of pins and temperature significantly affected the shear load of the brass pin. At room temperature, as the number of pins was increased, the shear load increased by 31.60% (six to eight) and 24.76% (eight to ten). Taking six pins as an example, the increase in the heating temperature from 22°C to 190°C decreased the shear load of the pin by 17.68%. The brass pin exhibited prominent plastic failure characteristics. Moreover, the shear section at room temperature was dominated by the shear band, which has a higher failure energy absorption capacity. As the temperature was increased, the area of fracture zone gradually increased, and consequently, the toughness and plasticity increased. This study provides a reference for the use of brass pins in downhole tools and reduces the possibility of premature shearing and related construction waste.