BV F620 va BV F690 po'lat plitalar orasidagi farq

BV F620 va BV F690 Bureau Veritas (BV) tomonidan sertifikatlangan-kritik, ultra{3}}yuqori-bardoshli po'lat plitalarning premium eshelonini ifodalaydi. "F" belgisi ularning eng talabchan ilovalarda{6}}kritik xizmatga bo'lgan malakasini aniq bildiradi. Bu navlar ekstremal va uzluksiz tsiklik dinamik yuklanishni boshdan kechiradigan konstruktiv komponentlar uchun moʻljallangan, masalan, chuqur{8}}dengizdagi dengizda bogʻlash tizimlari, oʻta ogʻir{9}}koʻtaruvchi kranlar poydevorlari va bom konstruksiyalari hamda dengizda suzuvchi shamol inshootidagi muhim boʻgʻinlar. Ularning asosiy dizayn talabi misli ko'rilmagan charchoq muddati, sinish chidamliligi va ultra{12}}yuqori statik quvvat bilan birga yoriqni ushlab turish qobiliyatini taqdim etishdir.

Asosiy farqlar:

Asosiy farq ularning kuch darajasidir. BV F620 460 MPa minimal oqish quvvatiga ega (620 MPa valentlik bilan), BV F690 esa 500 MPa (690 MPa valentlik bilan) yuqori oquvchanlikni belgilaydi. Bu F690 ni operatsion va eng yuqori yuklar ostida statik rentabellikka mutlaq maksimal qarshilikni talab qiladigan dizaynlar uchun eng yuqori tanlovga aylantiradi.

Beyond tensile strength, achieving the "F" grade at these levels demands exceptional metallurgical purity, a very fine and homogeneous microstructure, and guaranteed through-thickness properties. To attain the superior strength of F690 while simultaneously meeting the extreme fatigue and toughness thresholds, it requires the most advanced alloy design, typically with significant additions of Nickel, Molybdenum, and sometimes Copper, processed under extremely stringent thermo-mechanical controlled processing (TMCP) or quenching and tempering (Q&T). Consequently, BV F690 possesses a significantly higher carbon equivalent (Ceq) and crack sensitivity index compared to F620. This renders the fabrication of F690, particularly welding, exceedingly restrictive and complex. It mandates the use of specially developed, ultra-high-toughness consumables, meticulously controlled preheating (often >150 daraja ), tor o'tish oralig'idagi haroratli oynalar, juda past issiqlik kiritish va majburiy, aniq boshqariladigan{1}}payvandlashdan keyingi issiqlik bilan ishlov berish (PWHT). Shuning uchun, F690 ni F620 dan ko'ra tanlash, faqat eng yuqori charchoq ko'rsatkichi va statik quvvat talab qilingan hollarda oqlangan muhim muhandislik qaroridir, chunki u material narxining sezilarli darajada oshishiga olib keladi va eng talabchan ishlab chiqarish protokollarini talab qiladi.

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