Strengthening mechanisms of creep resistant tempered martensitic steel
Strengthening mechanisms of creep resistant tempered martensitic steel
复制标题
DOI：
10.2355/isijinternational.41.641
复制
发表时间：
2001-01-01
影响因子：
1.8
通讯作者：
Koike, J
中科院分区：
文献类型：
--
作者：
Maruyama, K;Sawada, K;Koike, J
本文根据实验数据对回火马氏体板条组织高铬铁素体钢的蠕变抗力和持久寿命进行了评述。重点讨论了铁素体钢的蠕变机理、进一步强化的合金设计和长期使用后的蠕变断裂强度损失等三个问题。高Cr铁素体钢的特点是具有细小的亚晶组织，亚晶内有高密度的自由位错。位错亚结构是钢中分布最密集的位错运动障碍。它的恢复控制蠕变速率和高温下的断裂寿命。提高钢的蠕变强度需要具有高密度自由位错的细亚晶结构。足够数量的钉扎颗粒（亚晶粒内部的MX颗粒和亚边界上的M23C6颗粒）是消除由于高位错密度而产生的大的回复驱动力所必需的。通过合理的合金设计，可以延缓钉扎颗粒的粗化和团聚，高Cr铁素体钢的持久强度在长期使用后迅速下降。如果我们能防止持久强度的损失，则可以实现蠕变持久强度的显著提高。在高温回火的钢中，沿沿着晶界的亚晶粒组织的增强的回复是过早失效和随后的断裂强度损失的原因。然而，这种情况并不总是适用的。解决高铬铁素体钢的这一重要问题还需要进一步的研究。MX颗粒对于保持细亚晶结构和实现高Cr铁素体钢的优异蠕变强度是必需的。MX颗粒的强化机制是另一个尚未解决的重要问题。
The creep deformation resistance and rupture life of high Cr ferritic steel with a tempered martensitic lath structure are critically reviewed on the basis of experimental data. Special attention is directed to the following three subjects: creep mechanism of the ferritic steel, its alloy design for further strengthening, and loss of its creep rupture strength after long-term use.The high Cr ferritic steel is characterized by its fine subgrain structure with a high density of free dislocations within the subgrains. The dislocation substructure is the most densely distributed obstacle to dislocation motion in the steel. Its recovery controls creep rate and rupture life at elevated temperatures. Improvement of creep strength of the steel requires a fine subgrain structure with a high density of free dislocations. A sufficient number of pinning particles (MX particles in subgrain interior and M23C6 particles on sub-boundaries) are necessary to cancel a large driving force for recovery due to the high dislocation density. Coarsening and agglomeration of the pinning particles have to be delayed by an appropriate alloy design of the steel.Creep rupture strength of the high Cr ferritic steel decreases quickly after long-term use. A significant improvement of creep rupture strength can be achieved if we can prevent the loss of rupture strength. In the steel tempered at high temperature, enhanced recovery of the subgrain structure along grain boundaries is the cause of the premature failure and the consequent loss of rupture strength. However, the scenario is not always applicable. Further studies are needed to solve this important problem of high Cr ferritic steel. MX particles are necessary to retain a fine subgrain structure and to achieve the excellent creep strength of the high Cr ferritic steel. Strengthening mechanism of the MX particles is another important problem left unsolved.