微观组织对X80直缝焊管与高压氢相容性影响研究

为研究不同组织X80直缝焊管与6.3 MPa氢气的相容性，采用扫描电镜分析、高压氢环境缺口试样慢拉伸试验等方法进行分析。结果表明，与6.3 MPa氮气条件相比，针状铁素体组织的Φ1 422 mm钢管母材缺口试样在6.3 MPa氢气中抗拉强度、断面收缩率和拉伸位移损失率分别为5.1 %、10.1 %和1.3 %；多边形铁素体+贝氏体组织的Φ1 219 mm钢管母材缺口试样在6.3 MPa氢气中的抗拉强度、断面收缩率和拉伸位移的损失率分别为4.9 %、62.8 %和13.7 %；针状铁素体Φ1 422 mm钢管母材相比多边形铁素体+贝氏体组织Φ1 219 mm钢管母材在6.3 MPa气态氢环境中具有更好的抗氢脆性能；Φ1 422 mm钢管直焊缝和Φ1 219 mm钢管直焊缝均为多边形铁素体组织；与氮气中相比，Φ1 422 mm钢管直焊缝在6.3 MPa氢气中的抗拉强度、断面收缩率和拉伸位移损失率分别为4.4 %、23.3 %和10.2 %；Φ1 219 mm钢管直焊缝在6.3 MPa氢气中的抗拉强度、断面收缩率和拉伸位移损失率分别为2.7 %、24.7 %和10.4 %。慢拉伸断口微观形貌表明6.3 MPa氢气的气体条件促进了氢致裂纹的萌生。

Effect of Microstructure on the Compatibility of X80 Straight Welded Pipe with High Pressure Hydrogen

In order to study the compatibility of two different microstructures X80 straight welded pipes with 6.3 MPa hydrogen, scanning electron microscopy （SEM） and slow tensile test of notched specimen were used to analyse. The results showed that, compared with the properties in 6.3 MPa nitrogen, the loss rates of tensile strength, reduction of area and tensile displacement of the notched specimen of Φ1 422 mm steel pipe base metal with acicular ferrite structure in 6.3 MPa hydrogen were 5.1%, 10.1% and 1.3%; the loss rates of tensile strength, reduction of area and tensile displacement of the notched specimens of Φ1 219 mm steel pipe base material with polygonal ferrite + bainite structure were 4.9 %, 62.8 % and 13.7% respectively in 6.3 MPa hydrogen. The acicular ferrite Φ1 422 mm steel pipe base material has better hydrogen embrittlement resistance than polygonal ferrite + bainite Φ1 219 mm steel pipe base material in 6.3 MPa gaseous hydrogen environment. Both Φ1 422 mm steel pipe straight weld and Φ1 219 mm steel pipe straight weld were polygonal ferrite structure. Compared with nitrogen environment, the loss rates of tensile strength, area reduction and tensile displacement of Φ1 422 mm steel pipe straight weld in 6.3 MPa hydrogen are 4.4%, 23.3% and 10.2% respectively, and the loss rates of tensile strength, area reduction and tensile displacement of Φ1 219 mm steel pipe straight weld in 6.3 MPa hydrogen are 2.7%, 24.7% and 10.4%. The micro morphology of slow tensile fracture showed that 6.3 MPa hydrogen gas condition promoted the initiation of hydrogen induced cracks.