高性能海底管线钢的铁素体相变规律

Ferrite transformation law of marine pipeline steel with high properties

采用Gleeble-1500D型热模拟试验机研究了高性能海底管线用钢的铁素体相变组织演变特征,观察不同变形温度、变形量和开冷温度对铁素体相变规律的影响。结果表明,增加变形量和降低变形温度均会促进形变诱导铁素体相变,加快铁素体析出,细化铁素体晶粒;降低开冷温度,铁素体转变量增加,但开冷温度过低时,铁素体晶粒会明显长大。为了获得细小弥散的铁素体组织,试验钢奥氏体未再结晶区变形温度应控制在780℃左右,变形量≥50%,开冷温度控制在700~660℃之间。

The microstructure evolution during ferrite transformation of high properties marine pipeline steel was studied by Gleeble-1500 D thermal simulator,and the ferrite transformation rules under different deformation temperature,deformation and start cooling temperature were observed. The results show that increase of deformation and decrease of deformation temperature can promote deformation induced ferrite transformation,accelerate ferrite precipitation and refine ferrite grain. Reducing start cooling temperature can improve amount of ferrite transformation,but the ferrite grains would be excessively coarse when the start cooling temperature is too low. In order to obtain fine and dispersively distributed ferrite grains,deformation temperature of austenite non-recrystallization region should be controlled about 780 ℃,deformation is over 50%,start cooling temperature is in the range of 700-600 ℃.