超大型液化石油气船用低温钢组织性能

 为了满足超大型液化石油气船的建造需要,介绍了采用铌、钛复合微合金化及控制轧制与控制冷却技术研制超大型液化石油气船用LT-FH32低温钢,并对其显微组织演变及力学性能进行系统研究。CCT曲线研究表明,当冷却速度小于3 ℃/s时,LT-FH32低温钢主要获得多边形铁素体和少量珠光体组织;冷却速度为5~15 ℃/s时,主要为多边形铁素体、针状铁素体和贝氏体的多相组织;当冷却速度大于20 ℃/s时,主要为板条贝氏体组织。经控制轧制和控制冷却获得的10和34 mm板厚的低温钢,其显微组织均为多边形铁素体和板条贝氏体多相组织。两种板厚的多相组织低温钢横、纵向性能差异不大,屈服强度为390~413 MPa,抗拉强度为485~521 MPa,-80 ℃夏比冲击功高于200 J,韧脆性转变温度为-100 ℃以下。

Microstructure and properties of low temperature steel for ultra large liquefied petroleum gas carrier

In order to meet the construction of ultra large liquefied petroleum gas carrier,the development of LT-FH32 low temperature steel for ultra large liquefied petroleum gas carrier with niobium and titanium composite microalloying,controlled rolling and controlled cooling technology were introduced. Microstructure evolution and mechanical properties were investigated systematically. Results from CCT curves suggested that when cooling rate was slower than 3 ℃/s,polygonal ferrite and pearlite was obtained in the studied LT-FH32 steel. While,multi-phase microstructure consisting of polygonal ferrite and bainite was obtained in wide range of cooling rate from 5 to 15 ℃/s. When cooling rate was 20 ℃/s,lath bainite was obtained. The developed LT-FH32 steel plates with 10 and 34 mm thickness consisted of polygonal ferrite and bainite. The two multi-phase microstructure steel plate exhibited similar mechanical properties from both sides of transverse and longitude. The yield strength was from 390 to 413 MPa,tensile strength was from 485 to 521 MPa,impact energy at -80 ℃ was higher than 200 J and DBTT was -100 ℃.