X80鋼級(jí)厚壁螺旋縫埋弧焊管導(dǎo)向彎曲不合格原因分析
Analysis of Causes for Nonconformance of Heavy-wall X80 SAWH Pipe to Guide Bending Test
-
摘要: 針對(duì)X80鋼級(jí)Φ1 219 mm×22 mm大直徑厚壁螺旋縫焊管試制過程中連續(xù)出現(xiàn)的導(dǎo)向彎曲試驗(yàn)不合格問題，通過化學(xué)成分分析、力學(xué)性能試驗(yàn)、顯微組織及開裂斷口形貌觀察等方法，對(duì)導(dǎo)向彎曲開裂原因進(jìn)行了分析。結(jié)果表明：開裂鋼管焊接接頭熱影響區(qū)存在明顯軟化；在斷口上多處存在的夾渣和氣孔等焊接缺陷誘發(fā)了斷裂的裂紋源；彎曲塑性變形引起熔合線附近粗晶區(qū)中硬而脆的M/A島與板條鐵素體基體間的界面產(chǎn)生較大的應(yīng)力集中，導(dǎo)致彎曲開裂。提出了有針對(duì)性的建議。Abstract: Addressing the problem of frequent occurrence of nonconformance of the Φ1 219 mm×22 mm largesized， heavy-wall X80 SAWH pipe to the guide bending test as identified during the trial production process，investigation into the causes for cracking of the guide bending test specimen is conducted by means of chemical composition analysis，mechanical property testing，and observation of microstructure and rupture morphology of the specimen，etc.As a result，it is found that the said specimen’s cracking is caused by the circumstances as follows.There exists obvious softening of the HAZ of the pipe’s weld joint.A lot of welding defects like slag inclusions and porosities as staying in the rupture area induce the crack source of the rupture.And the bending plastic deformation leads to remarkable stress concentration at the interface between the hard and brittle M/A island in the coarse grain zone near the weld bond and the lath ferrite matrix.Accordingly，relevant suggestions are put forward.
下載: