High strength means great resistance to plastic deformation. High toughness means great resistance to crack growth and breakage because the material is malleable.

The impact strength is determined in the notched-bar impact test and provides information about how resistant a material is to impact loads. It indicates how well a material can withstand a blow or impact without breaking. The impact strength is given in J/cm².

Impact strength is typically measured through various tests that simulate a material's ability to withstand a sudden impact. A common test, for example, is the Charpy V test, in which a specially shaped impactor is dropped onto a sample of the material to be tested. Impact strength is then measured by the energy required to break or indent the sample.