The changes in the mechanical behavior of electric resistance welded（ERW） pipes before and after the cage roll forming process were investigated through tensile experiments. It is found that the Bauschinger effect d...The changes in the mechanical behavior of electric resistance welded（ERW） pipes before and after the cage roll forming process were investigated through tensile experiments. It is found that the Bauschinger effect does not exist in the pipe product, while the work hardening effect introduced by pipe-making is the direct cause of the mechanical changes. The prestrain introduced during different pipe-making processes are accumulative to the work hardening effect. And the increment of the yield strength for making Ф 244.48 × 8.94 pipe is approximately 45 MPa, higher than that of hot-rolled plates. It is verified that the strain ε=t/D-t is an efficient index representing the work hardening effect from the engineering viewpoint.展开更多
In this study,the effect of welding parameters on the microstructure and mechanical properties of the dissimilar resistance spot welded DP1000–QP1180 joints was investigated.Heat affected zone(HAZ)width of QP1180 sid...In this study,the effect of welding parameters on the microstructure and mechanical properties of the dissimilar resistance spot welded DP1000–QP1180 joints was investigated.Heat affected zone(HAZ)width of QP1180 side was smaller than that of DP1000 side.HAZ width and indentation depth increased with increasing welding current and welding time.The nugget size increased with increasing welding current whereas it increased at lower currents and decreased at higher currents with increasing welding time.The lowest hardness was on the DP1000 side.On the QP1180 side,the center of HAZ had the peak hardness.With increasing welding current,hardness values throughout the weld zone decreased and the tensile shear load increased.At lower welding currents,the welding time did not affect the tensile shear load.Tensile elongation decreased with the increase of welding time,whereas there is no relationship between the welding current and elongation.The spot-welded joints having higher strength exhibited a more ductile fracture characteristic.展开更多
文摘The changes in the mechanical behavior of electric resistance welded（ERW） pipes before and after the cage roll forming process were investigated through tensile experiments. It is found that the Bauschinger effect does not exist in the pipe product, while the work hardening effect introduced by pipe-making is the direct cause of the mechanical changes. The prestrain introduced during different pipe-making processes are accumulative to the work hardening effect. And the increment of the yield strength for making Ф 244.48 × 8.94 pipe is approximately 45 MPa, higher than that of hot-rolled plates. It is verified that the strain ε=t/D-t is an efficient index representing the work hardening effect from the engineering viewpoint.
基金Project supported by Beycelik Gestamp Inc.,Turkey
文摘In this study,the effect of welding parameters on the microstructure and mechanical properties of the dissimilar resistance spot welded DP1000–QP1180 joints was investigated.Heat affected zone(HAZ)width of QP1180 side was smaller than that of DP1000 side.HAZ width and indentation depth increased with increasing welding current and welding time.The nugget size increased with increasing welding current whereas it increased at lower currents and decreased at higher currents with increasing welding time.The lowest hardness was on the DP1000 side.On the QP1180 side,the center of HAZ had the peak hardness.With increasing welding current,hardness values throughout the weld zone decreased and the tensile shear load increased.At lower welding currents,the welding time did not affect the tensile shear load.Tensile elongation decreased with the increase of welding time,whereas there is no relationship between the welding current and elongation.The spot-welded joints having higher strength exhibited a more ductile fracture characteristic.
