"压缩永久变形" can be translated into English as "compression permanent set" or "compression set" (the more commonly used term in the industry).
Compression permanent set directly emphasizes the permanent nature of the deformation under compression.
Compression set is a widely accepted and concise term in materials science and engineering, referring to the irreversible deformation remaining after a material has been compressed and then allowed to recover.
Both expressions are correct, but "compression set" is more frequently encountered in technical literature and industry standards.