Strength and toughness relationships are perhaps the most important ones when it comes to advances in materials and engineered products. Toughness is often determined by impact testing, and every heat treater needs to know how these tests are performed and what they mean. Let’s learn more.
One of the surprising phenomena in the metals industry is that normally ductile materials, such as mild steel, can become brittle under certain conditions. There are three basic factors that contribute to a brittle-type (or cleavage-type) fracture, namely: the presence of a triaxial stress state (defined later), a low temperature (relative to the ductile-to-brittle transition temperature) for the material in question and a high strain rate or rapid rate of loading.