X100管线钢冷裂纹敏感性研究

摘要

采用插销试验方法研究了埋弧焊条件下X100管线钢热影响区的冷裂纹敏感性及断口特性.试验结果表明,X100管线钢在不预热条件下对冷裂纹不敏感,临界断裂应力σcr为823.5 MPa,与其抗拉强度Rm (823 MPa)相当,可在不预热条件下焊接.当拘束应力继续增大时,发生时效断裂,断口性质为典型的氢致延迟断裂.X100级管线钢抗冷裂纹性好,主要与X100级管线钢Ceq (Pcm)不高(0.21％)、HAZ淬硬不明显有关,过热区组织为粒状B+F,硬度最大为266 HV10,低于临界硬度350 HV10；此外,埋弧焊接方法t100较大,焊接过程中氢逸出时间长；熔渣在隔绝空气的同时CaF2可去除氢,使电弧在低氢的焊接条件下燃烧.%The cold cracking sensitivity and fracture characteristics of XI00 pipeline steel HAZ were studied by using submerged-arc welding and implant test. The result indicated that in the case of no preheating, X100 pipeline steel is insensitive to cold cracking, the critical fracture stress cra is 823.5 Mpa, which is equivalent to the tensile strength Rm (823 MP), so steel can be welded without preheating. When the constraint stress increases continuously, the aging fracture occurs, the fracture characteristics is typical hydrogen induced crack. The reason for high resistance to cold cracking of X100 pipeline steel is mainly due to Ceq (Pcm) forO. 21%, HAZ hardening is not obvious. The structure of overheated zone is granular B+F, the maximum hardness value is 266HV)0, which is lower than the critical hardness value of 35OHV1O. Furthermore, the f100 is lager, and the time of hydrogen escape is much long during submerged-arc welding process. The sinter can isolate air, and CaF2 can eliminate hydrogen, so that the electric arc can be combustion in low hydrogen.