Fracto graphic features in metals and plastics：Fractographic features are critical to failure analysis of metals and plastics

摘要

Fractography is the science of examining fracture surfaces. When material failure involves actual breakage, fractography can identify the fracture origin, direction of crack propagation, failure mechanism, material defects, environmental interaction, and the nature of stresses. Fractography of plastics is a relatively new field, with many similarities to metals. Common failure modes include ductile overload, brittle fracture, impact, and fatigue. Analogies can also be drawn between stress corrosion cracking (SCC) in metals/ stress cracking in plastics, corrosion/ chemical aging, de-alloying/scission, residual stress/frozen-in stress, and welds/knit lines. Stress raisers, microstructure, material defects, and thermo-mechanical history play important roles in both materials. This article describes some of the macroscopic and microscopic features considered by the failure analyst to evaluate fracture surfaces of metals and plastics. It discusses several case histories in. order to explain, key fractographic features for metals and plastics, and to compare and contrast various aspects of failure analysis and fractography.