Gas Transmitting From West to East Project' is significant. It should ensure the welding quality and safety of pipeline. The task is very arduous to guarantee the quality of the project in the condition of long li...Gas Transmitting From West to East Project' is significant. It should ensure the welding quality and safety of pipeline. The task is very arduous to guarantee the quality of the project in the condition of long line, complex weather and geology features. In this paper, the welding cold cracking susceptibility of domestic X 70 pipeline steel adopted by the project, which is one of the most interesting questions of welding quality about petrol pipeline, was studied by means of oblique Y groove cracking test. The crack ratio of surface and section was tested under the conditions of different welding materials and preheat temperature .The thickness of plate steel was 14.7 mm and 10.3 mm . The results reveal that X 70 pipeline steel has good crack resistance. The research has important value for the construction of large scale pipeline engineering and the application of domestic X 70 pipeline steel.展开更多
The slitting process for manufacturing REBa2Cu3O7δ(REBCO,RE=Rare earth)tapes of required width significantly improves the production efficiency and reduces production costs.However,edge cracks induced by the slittin...The slitting process for manufacturing REBa2Cu3O7δ(REBCO,RE=Rare earth)tapes of required width significantly improves the production efficiency and reduces production costs.However,edge cracks induced by the slitting process of wide REBCO tapes may cause premature degradation under high tensile stress in highfield magnets.Therefore,it is necessary to evaluate the effect of edge cracks of REBCO tapes on the critical current(Ic)degradation.Firstly,Ic degradation under artificial cracks was measured to validate the applicability of linear elastic fracture mechanics for the REBCO layer.The maximum circumferential stress criterion was used to derive the mixed-mode stress intensity factor of multiple oblique edge cracks.A semi-analytical model considering edge crack properties such as angleβ,spacing d,and length a,was built to evaluate the critical load and critical crack.We found that when the stress intensity factor at the crack tip is below KIC?2:3 MPa ffiffiffiffim p,edge cracks did not propagate.We examined commercial REBCO tapes manufactured by two different processes,concluding that edge cracks in these tapes will not cause premature degradation.展开更多
文摘Gas Transmitting From West to East Project' is significant. It should ensure the welding quality and safety of pipeline. The task is very arduous to guarantee the quality of the project in the condition of long line, complex weather and geology features. In this paper, the welding cold cracking susceptibility of domestic X 70 pipeline steel adopted by the project, which is one of the most interesting questions of welding quality about petrol pipeline, was studied by means of oblique Y groove cracking test. The crack ratio of surface and section was tested under the conditions of different welding materials and preheat temperature .The thickness of plate steel was 14.7 mm and 10.3 mm . The results reveal that X 70 pipeline steel has good crack resistance. The research has important value for the construction of large scale pipeline engineering and the application of domestic X 70 pipeline steel.
基金the Strategic Priority Research Program of Chinese Academy of Sciences under Grant No.XDB25000000the National Natural Science Foundation of China under Grant No.52007089.
文摘The slitting process for manufacturing REBa2Cu3O7δ(REBCO,RE=Rare earth)tapes of required width significantly improves the production efficiency and reduces production costs.However,edge cracks induced by the slitting process of wide REBCO tapes may cause premature degradation under high tensile stress in highfield magnets.Therefore,it is necessary to evaluate the effect of edge cracks of REBCO tapes on the critical current(Ic)degradation.Firstly,Ic degradation under artificial cracks was measured to validate the applicability of linear elastic fracture mechanics for the REBCO layer.The maximum circumferential stress criterion was used to derive the mixed-mode stress intensity factor of multiple oblique edge cracks.A semi-analytical model considering edge crack properties such as angleβ,spacing d,and length a,was built to evaluate the critical load and critical crack.We found that when the stress intensity factor at the crack tip is below KIC?2:3 MPa ffiffiffiffim p,edge cracks did not propagate.We examined commercial REBCO tapes manufactured by two different processes,concluding that edge cracks in these tapes will not cause premature degradation.
