Failure analysis of die casting pins for an aluminum engine block. (October 2019)

• Record Type: Journal Article
• Authors: Kang, Se-Hyung; Han, Jung-Jin; Hwang, Won-Tae; Lee, Sang-Min; Kim, Ho-Kyung
• Is Part Of: Engineering failure analysis. Volume 104(2019)
• Page Start: 690
• Page End: 703
• Publication Date: 2019-10
• Subjects: Die-casting die pins -- AISI H13 tool steel -- Fatigue failure -- Thermal stress; System failures (Engineering) -- Periodicals; Fracture mechanics -- Periodicals; Reliability (Engineering) -- Periodicals; Pannes -- Périodiques; Rupture, Mécanique de la -- Périodiques; Fiabilité -- Périodiques; Fracture mechanics; Reliability (Engineering); System failures (Engineering); Periodicals; Electronic journals; 620.112
• DOI: 10.1016/j.engfailanal.2019.06.053
• Languages: English
• ISSNs: 1350-6307

Abstract

Abstract: This paper describes an investigation which was done on prematurely failed pins used in die-casting dies for aluminum engine blocks. To investigate the causes of the failures, static and fatigue strength evaluations of the pin materials and the deterioration degree of the strength due to exposure to high temperatures were evaluated. SEM observations of the fracture surfaces of broken pins revealed that the fractures were the fatigue failure type caused by thermal stresses upon thermal expansion and cooling during the repeated die-casting process. A solidification analysis of the die-casting process was conducted to determine the temperature distribution of the dies and pins, and a coupled thermal-structure analysis was carried out using the temperature distribution information to determine the magnitude of the thermal stress in the pin. The maximum thermal stresses were used to predict the fatigue lifetime of the pin. The result of this investigation reveals that cooling holes at the center of the pin were machined with some degree of eccentricity, leading to a concentration of the thermal stress at the thin part and, ultimately resulting in a premature failure. Appropriate machining of a cooling hole in the die pins must be carried out in order to avoid premature failures of these components. Hightlights: Pins used in die-casting dies for aluminum engine blocks prematurely failed. Fracture surfaces of broken pins are the fatigue failure caused by thermal stress. Coupled thermal-structure analysis was carried out to determine the thermal stress Cooling holes with eccentricity caused a concentration of the thermal stress.