X100管线钢焊接接头抗HIC性能研究

Resistance to Hydrogen Induced Corrosion Cracking of Weld Joint of X100 Pipeline Steel

利用OM和SEM研究了X100管线钢焊接接头的微观组织,并利用EDS分析接头中的非金属夹杂物种类及成分。结果表明,实验用X100管线钢焊接接头由针状铁素体、粒状贝氏体和M/A岛组成;焊缝金属中含有MnS,Si的氧化物和Al的氧化物及Al-Mg-O和Ca-Al-O-S系夹杂物。焊接接头氢致开裂敏感性较高,焊缝金属中的非金属夹杂物及硬脆M/A组元与基体之间的界面和应力导致氢致裂纹的萌生,并沿粗大的贝氏体晶粒扩展。

The resistance to hydrogen induced corrosion cracking(HIC) of the weld joint of X100pipeline steel prepared by gas shielding metal arc welding was studied. OM and SEM with EDS were adopted to characterize the microstructure of the X100 weld joint and the non-metallic inclusions. The experimental results presented that the X100 weld joint exhibited a microstructure consisted of acicular ferrite, bainite and M/A islets, MnS, Al-oxide, Si-oxide and Al-Mg-O, Ca-Al-O-S mixed inclusions were also found in the weld joint. The weld joint had a high susceptibility to HIC due to the large amounts of non-metallic inclusions, furthermore, the interfaces and stress between the matrix and brittle M/A islets as well as inclusions might play an important role in the initiation of HIC cracks and then the cracks propagated along the grain boundaries of the coarse bainite.