The effects of postweld heat treatment on the microstructure and metallurgical properties of a bronze–carbon steel(st37)explosively bonded interface were studied.Explosive welding was done under 1.5-and 2-mm standoff...The effects of postweld heat treatment on the microstructure and metallurgical properties of a bronze–carbon steel(st37)explosively bonded interface were studied.Explosive welding was done under 1.5-and 2-mm standoff distances and different conditions of explosive charge.Samples were postweld heat treated for 4 and 16 h in the furnace at 250°C and 500°C and then air cooled.Laboratory studies using optical microscopy,scanning electron microscopy,and microhardness testing were used to evaluate the welded samples.Microstructural examinations showed that by increasing the standoff distance and the explosive charge,the interface of bronze to steel became wavier.The microhardness test result showed that the hardness of the samples was higher near the joint interface compared with other areas because of the intensive plastic deformation,which was caused by the explosion force.The results show that increasing the heat treatment temperature and time caused the intermetallic compounds’layer thickness to increase,and,because of the higher diffusion of copper and tin,the iron amount in the intermetallic compounds decreased.Also,because of the increase in heat treatment temperature and time,internal stresses were released,and the interface hardness decreased.展开更多
This study was done to evaluate the nugget zone(NZ)corrosion behavior of dissimilar copper/brass joints welded by friction stir lap welding(FSLW)in a solution of 0.015 mol/L borax(pH 9.3).To this end,dissimilar copper...This study was done to evaluate the nugget zone(NZ)corrosion behavior of dissimilar copper/brass joints welded by friction stir lap welding(FSLW)in a solution of 0.015 mol/L borax(pH 9.3).To this end,dissimilar copper/brass plates were welded with two dissimilar heat inputs(low and high)during the welding procedure.The high and low heat inputs were conducted with 710 r/min,16 mm/min and 450 r/min,25 mm/min,respectively.Using open circuit potential(OCP)measurements,electrochemical impedance spectroscopy(EIS)and Tafel polarization tests,the electrochemical behavior of the specimens in borate buffer solution was assessed.With the help of scanning electron microscope(SEM),the morphology of welded specimen surfaces was examined after immersion in the test solution.According to the results,the NZ grain size and resistance improvement reduced due to the nugget zone corrosion with a decreased heat input.The results obtained from Tafel polarization and EIS indicated the improved corrosion behavior of the welded specimen NZ with a decrease in the heat input during the welding process unlike the copper and brass metals.Furthermore,an increased heat input during the welding process shows a reduction in the conditions for forming the passive films with higher protection behavior.展开更多
文摘The effects of postweld heat treatment on the microstructure and metallurgical properties of a bronze–carbon steel(st37)explosively bonded interface were studied.Explosive welding was done under 1.5-and 2-mm standoff distances and different conditions of explosive charge.Samples were postweld heat treated for 4 and 16 h in the furnace at 250°C and 500°C and then air cooled.Laboratory studies using optical microscopy,scanning electron microscopy,and microhardness testing were used to evaluate the welded samples.Microstructural examinations showed that by increasing the standoff distance and the explosive charge,the interface of bronze to steel became wavier.The microhardness test result showed that the hardness of the samples was higher near the joint interface compared with other areas because of the intensive plastic deformation,which was caused by the explosion force.The results show that increasing the heat treatment temperature and time caused the intermetallic compounds’layer thickness to increase,and,because of the higher diffusion of copper and tin,the iron amount in the intermetallic compounds decreased.Also,because of the increase in heat treatment temperature and time,internal stresses were released,and the interface hardness decreased.
文摘This study was done to evaluate the nugget zone(NZ)corrosion behavior of dissimilar copper/brass joints welded by friction stir lap welding(FSLW)in a solution of 0.015 mol/L borax(pH 9.3).To this end,dissimilar copper/brass plates were welded with two dissimilar heat inputs(low and high)during the welding procedure.The high and low heat inputs were conducted with 710 r/min,16 mm/min and 450 r/min,25 mm/min,respectively.Using open circuit potential(OCP)measurements,electrochemical impedance spectroscopy(EIS)and Tafel polarization tests,the electrochemical behavior of the specimens in borate buffer solution was assessed.With the help of scanning electron microscope(SEM),the morphology of welded specimen surfaces was examined after immersion in the test solution.According to the results,the NZ grain size and resistance improvement reduced due to the nugget zone corrosion with a decreased heat input.The results obtained from Tafel polarization and EIS indicated the improved corrosion behavior of the welded specimen NZ with a decrease in the heat input during the welding process unlike the copper and brass metals.Furthermore,an increased heat input during the welding process shows a reduction in the conditions for forming the passive films with higher protection behavior.
