The correct selection of the hot piercing temperature can not only effectively reduce the deformation resistance

main reasons causing uneven wall thickness of the hollow pipe

The current system for designating steel product grades in China is based on two recommended national standards: GB/T 221-2008 "Designation Method of Steel Products" and GB/T 17616-2013 "Unified Numerical Code System for Steels and Alloys". The former employs a naming method that combines Chinese pinyin, chemical element symbols, and Arabic numerals. The latter, on the other hand, has established a systematic numerical coding system. The standard stipulates that all steel and alloy products listed in national or industry standards should be assigned both a brand name and a unified numerical code, which are used in parallel and correspond to each other.

Zone I is called the piercing preparation zone (rolling billet tube zone). The main function of Zone I is to prepare for the piercing and successfully achieve the second bite.