低成本高焊接性能船板钢EH36的开发

工业化试制了3种厚度规格(20,26和36mm)的新型低成本高焊接性能船板钢EH36。试制钢板的显微组织由多边形铁素体和针状铁素体构成,其力学性能满足EH36级别船板要求并具有优异的低温韧性。采用焊接热模拟评价了钢板的焊接性能,当热输入由30kJ/cm升高至160kJ/cm时,粗晶区原奥氏体晶粒尺寸逐渐增大,其组织也逐渐由粒状贝氏体向晶界铁素体+晶内针状铁素体+晶内多边形铁素体转变,维氏硬度逐渐下降,低温韧性优异。得益于TiN粒子对奥氏体晶粒长大的抑制作用,微量B元素对先共析铁素体转变的抑制作用以及BN粒子对晶内铁素体形核的促进作用,焊接粗晶区获得了有利于韧性的细化组织,保证了粗晶区具有优异的低温韧性。双丝埋弧焊试验也验证了钢板具有优异的焊接性能。

Development of Low Cost Shipbuilding Steel EH36 With Enhanced Weldability

New type low cost shipbuilding steel EH36 with different thickness (20, 26, 36mm) were industrially produced by using advanced steel-making and thermo-mechanically controlled processing technology, the plates with excellent low temperature toughness having a microstructure of polygonal ferrite and acicular ferrite satisfy the mechanical properties of EH36. Thermal simulation was conducted to evaluate the plate weldability, with the increase of heat input from 30 to 160kJ/cm, austenite grain size (AGS) of coarse grain heat-affected zone (CGHAZ) increased, Vickers hardness decreased, and microstructure becomed grain boundary ferrite, intra-granular acicular ferrite and intra-granular ferrite instead of granular bainite, and the results show the plate has excellent toughness. The refined grain structure of CGHAZ which lead to excellent toughness results from such factors: prohibition of austenite grain growth by TiN particles, prevention of Widmanstatten ferrite formation by boron segregation at austenite grain boundary and promote of intra-granular ferrite formation by TiN and BN. The results above were also proved by tandem submerged arc welding.