Evaluation of Cracking at Cooling Holes in Aluminum Alloy Dies for Die Casting by Rotary Bending Fatigue Test

Abstract

  A new test method to reproduce cracking at cooling holes in die casting dies by means of a test piece for rotary bending fatigue test was developed. Underwater and air rotary bending fatigue tests were carried out to observe the test piece fracture surfaces by SEM. The result showed that the fatigue life of test pieces experimented with underwater was shorter by approximately 1/5 than those tested in atmosphere. The fracture morphology of the test pieces tested underwater was very similar to the fracture surface of a part of the insert cracked from a cooling hole which occurred during the die casting production. It was confirmed that by using this test method, cracking at cooling holes in die casting dies can be improved by adding rust inhibitor to the cooling water.