X70管线钢低温韧性研究

采用冲击试验研究了X70高等级管线钢的低温性能，分析其低温韧性与组织特征的关系。试验结果表明，管线钢具有良好的低温韧性，按照能量法确定韧脆转变温度为--79。c。由于X70管线钢具有细小的有效晶粒尺寸，裂纹在扩展过程中频繁改变断裂路径，提高了抵抗解理断裂能力，使其具有良好的低温韧性。

The low-temperature toughness of a X70 pipe-line steel was studied by impact test, as well as the correlation of low-temperature toughness and micro structural characteristics were investigated. Pipe-line steel has good low temperature toughness proved by regression analysis, ductile-brittle transition temperature （DBTT） was -79 ~C. Cleavage crack propagation direction deflected frequently because of fine effective grain size, resulting in an increased resistance for cleavage fracture, which contributes to excellent low-temperature toughness.