Weldability Analysis And Research Of X100 Pipeline Steel

This article uses the deposited metal diffusion hydrogen test,implant test,inclined y type groove docking experiment,the highest heat affected zone hardness method,welding thermal simulation test,and through the analytical means of microstructure,fracture morphology,impact toughness and hardness,respectively from different diffusion hydrogen content,different preheating temperature and welding heat input on three aspects of X100 pipeline steel weldability has systematically carried on the analysis and research,the results showed that:With the loss of the diffusion hydrogen content and preheating temperature increases,X100 pipeline steel critical fracture stress increases gradually.When diffusion hydrogen content of 3.333 ml/100 g,the critical fracture stress ?cr only 390 MPa,well below the 0.75?s.The rest of the test solution obtained the critical fracture stress were higher than 0.75?s,Implant test fracture include cleavage fracture,quasi cleavage fracture and dimple,secondary crack and fracture surface are obvious.With lower diffusion hydrogen content and preheating temperature increases,the formation of the intergranular fracture characteristics gradually disappear,the secondary crack gradually reduce,dimple progressively,become deeper.With the loss of the diffusion hydrogen content and preheating temperature increases,HAZ hardness value significantly reduced.When diffusion hydrogen content of 3.333 ml/100 g,HAZ hardness maximum value reached 328 HV10,basic close to the root of crack critical hardness value 330 HV10.The rest of the test solution obtained the hardness maximum value were lower than the international welding society(the IIW)proposed by critical hardness 350 HV10,cold cracks are less than the root crack critical hardness value 330 HV10.The electrode E9010-G adopt 80?×1h baking,and the X100 pipeline steel adopt 80?,120?,160?three preheating,method of Y-groove cracking test shows that the surface of the weld crack rate,root crack rate and fracture crack is 0,no cold cracking tendency.With the increase of welding heat input,CGHAZ impact energy significantly reduced.When heat input is at 10~15 KJ/cm,the impact energy basic close to the parent metal,toughness is better.When the heat input is greater than 25 KJ/cm,impact energy have fallen sharply,CGHAZ embrittlement phenomenon more and more significant.With the increase of welding heat input the CGHAZ grain hardness gradually reduce.When the heat input in 10 to 20KJ/cm,hardness value higher than parent metal,the embrittlement phenomenon happened,So when the welding heat input is 25 KJ/cm,X100 pipeline steel weldability better.