Creep

Creep refers to the phenomenon where a material undergoes slow, permanent deformation over time under constant stress (or load). In foreign trade, this term is commonly found in technical specifications, quality inspections, and contract clauses for products such as metals, plastics, and rubber, especially when high-temperature or long-term load-bearing components (e.g., pipes, fasteners, seals) are involved. Usage scenarios include: when exporting mechanical parts, the buyer may require a creep test report; when signing long-term supply contracts, the creep limit of the material within its design life must be specified. Note: Creep is often confused with 'cold flow,' but cold flow usually refers to creep of plastics at room temperature, while creep can occur at high temperatures; it differs from 'stress relaxation,' which is the decrease of stress over time under constant strain. Foreign trade practitioners should pay attention to the provisions of different standards (e.g., ASTM, ISO) regarding creep test conditions (temperature, stress, time) to avoid quality disputes caused by misunderstandings.