Study on Correlation of Orientation and Impact Properties in HTP Line-Pipe Steel

The correlation of impact properties, orientation and temperature in HTP70 line-pipe steel were studied by use of OM, TEM and macroscope fractography based on series temperature Charpy notch impact test of sample with different orientation. The results showed that: HTP70 steel line-pipe has seriously anisotropic properties, the mechanical behaviors vary with the orientation of parallel, 45° and vertical to rolling direction. The samples which parallel to rolling direction have higher impact energy and demixing crack incline. The demixing crack was caused by banding defect, it was affect by dislocation configuration and has certain direction character, and was related to temperature.