GT90連續(xù)油管對(duì)接焊接頭的組織和性能分析

Microstructure and Mechanical Properties of Butt Welding Joint of GT90 Coiled Tubing

摘要: 對(duì)GT90連續(xù)油管進(jìn)行焊接工藝試驗(yàn)，分析其焊接接頭組織及力學(xué)性能。分析認(rèn)為：GT90連續(xù)油管焊接接頭的焊縫組織為粒狀貝氏體；由于焊接熱循環(huán)的作用，焊接接頭的熱影響區(qū)出現(xiàn)軟化，導(dǎo)致硬度、強(qiáng)度降低，在疲勞彎曲變形過(guò)程中，應(yīng)變集中于軟化區(qū)并發(fā)生斷裂，使得接頭疲勞壽命低于母材。對(duì)于連續(xù)油管，應(yīng)采用較小的線能量進(jìn)行焊接，以減少軟化現(xiàn)象，改善接頭力學(xué)性能不均，從而提高焊接接頭的疲勞壽命。

Abstract: Welding procedure test is conducted on the GT90 coiled tubing to analyze the structure and mechnical properties of its weld joint.It is concluded that the weld joint is of granular bainite structure;and due to the effect of welding thermal cycle,the butt welding weld joint HAZ shows softening that will result in decreased hardness and strength.During the process of fatigue bending deformation,strain will concentrate at the soften area and lead to fracture,which will make the fatigue life of the joint lower than that of the parent metal.So,in order to reduce softening phenomenon,improve mechanical properties and increase fatigue life of a weld joint,it is recommended to use smaller linear energy input to weld a coiled tubing.