Impact Strength

Impact strength is a key indicator of a material's mechanical properties, referring to its ability to resist fracture or absorb energy under sudden impact loads, usually expressed in joules (J) or kilojoules per square meter (kJ/m²). In foreign trade, this term commonly appears in specifications, quality inspection reports, and contracts for products such as plastics, rubber, metals, packaging materials, and building materials. Especially for safety-related parts (e.g., helmets, automotive components, protective packaging), customers will explicitly require impact strength values. Notes: Results from different test standards (e.g., ISO 179, ASTM D256) are not directly comparable; before quoting or signing a contract, confirm the test method, specimen type (notched/unnotched), and temperature conditions. If a contract only states 'high impact strength' without specific values, disputes are likely. Difference from 'tensile strength': the latter reflects maximum stress under static tension, while impact strength reflects dynamic instantaneous fracture resistance; also different from 'hardness'—high hardness does not necessarily mean good impact strength (e.g., ceramics are hard but brittle). Foreign trade practitioners should require suppliers to provide third-party test reports and specify the standard and values in the PI.