Phenomena related to an alternate means of preparing steel for discontinuous hot dip galvanizing ... more Phenomena related to an alternate means of preparing steel for discontinuous hot dip galvanizing using aluminum-containing galvanizing baths are presented in this paper, using electroless deposition of thin layers of Ni-P as a steel pretreatment before immersion in molten Zn-5 % Al alloy. By this means, the use of fluxes is eliminated. The greater chemical affinity of Ni to Al, compared with Fe and Zn, allows for control of the role of Al in the galvanizing reaction.
Abstract Advanced high strength steels (AHSS), specifically dual phase (DP) steels, are extensive... more Abstract Advanced high strength steels (AHSS), specifically dual phase (DP) steels, are extensively used to reduce the weight of vehicles. Fiber laser welding (FLW) has been shown to provide welds with superior mechanical properties made at high welding speeds. Galvannealing (GA) and galvanizing (GI) coated sheet steels are extensively used for auto bodies to improve corrosion resistance. As such, the effect of coating type on the microstructure, mechanical properties and fatigue properties of FLW similar joints of DP980 was assessed. There existed spherical tempered martensite in the GA coated DP980 base metal (BM), most likely caused by the galvannealing process. Coating type did not present a noticeable effect on the microstructure of the welded zones. The GI coating, however, could evaporate violently during welding, resulting in high concavity and other welding defects which negatively affect the high-cycle fatigue property. Measures to mitigate the negative effects of the GI coating were discussed.
This paper investigates the gas jet wiping process, which is widely employed for controlling the ... more This paper investigates the gas jet wiping process, which is widely employed for controlling the final zinc-alloy coating thickness of a moving steel strip in the continuous hot-dip galvanizing process. In this study, large eddy simulation (LES) was employed to determine the effect of lower velocity symmetric auxiliary jets on main jet stabilization and coating thickness reduction during the gas jet wiping process. For validation purposes, experimental measurements of coating thickness were also carried out for the prediction of final coating thickness via a novel prototype multi-slot air knife used as the wiping actuator. Good agreement was found between the experimental measurements and model predictions for the coating weight, which also confirmed the applicability of the Elsaadawy et al. 1 model for the prediction of final coating weight for the multi-slot air knife geometry used. It was found that the jet flapping observed during single jet wiping could be prevented through use of the multi-slot air knife operating with lower velocity symmetric auxiliary jets (Re a /Re m = 0.45) situated on both sides of the main jet. The auxiliary jets modified the flow field in the main jet shear layer and diminished the formation of alternating vortices, which are the main cause of jet flow oscillations. As a result, a stabilized impinging flow with a longer potential core was found for the multi-slot jet configuration. This led to increased pressure gradient and increased shear stresses in the vicinity of the wiping region and, consequently, lower coating weights were obtained through use of the multi-slot air knife compared to the conventional single slot jet.
Continuous extruders have replaced the ram-press as the most common and economical means of produ... more Continuous extruders have replaced the ram-press as the most common and economical means of producing lead sheathed power cables. The intrinsic ability of the extruder to produce a significantly more uniform sheath composition should allow for a more dilute version of standard alloy compositions to be used, with equal or better performance of the sheath in service. No power cable
Abstract Grain boundary engineering (GBE) has lately been recognized as a viable approach to mani... more Abstract Grain boundary engineering (GBE) has lately been recognized as a viable approach to manipulate grain boundary characteristics to improve resistance against intergranular degradation. One of the most challenging intergranular degradation phenomena is liquid-metal-embrittlement (LME), where a reactive liquid metal penetrates along random grain boundary network. In contrast to random grain boundaries, special coincidence site lattice (CSL) boundaries has been shown to be resistant against the embrittlement. The present study investigates the feasibility of using a GBE technique to arrest LME in a Fe (FCC)-Zn couple. Two sets of low-strain-heat-treatment processing routes were used to optimize grain boundary characteristics based on: (a) Σ3 and Σ3n boundaries frequency, and (b) the material's texture and grain size evolution. The optimum characteristics resulted in significantly improved resistance against LME. The mechanism of the embrittlement arrest is discussed based on the random-grain boundary network continuity and the grain boundary triple junctions distributione.
Phenomena related to an alternate means of preparing steel for discontinuous hot dip galvanizing ... more Phenomena related to an alternate means of preparing steel for discontinuous hot dip galvanizing using aluminum-containing galvanizing baths are presented in this paper, using electroless deposition of thin layers of Ni-P as a steel pretreatment before immersion in molten Zn-5 % Al alloy. By this means, the use of fluxes is eliminated. The greater chemical affinity of Ni to Al, compared with Fe and Zn, allows for control of the role of Al in the galvanizing reaction.
Abstract Advanced high strength steels (AHSS), specifically dual phase (DP) steels, are extensive... more Abstract Advanced high strength steels (AHSS), specifically dual phase (DP) steels, are extensively used to reduce the weight of vehicles. Fiber laser welding (FLW) has been shown to provide welds with superior mechanical properties made at high welding speeds. Galvannealing (GA) and galvanizing (GI) coated sheet steels are extensively used for auto bodies to improve corrosion resistance. As such, the effect of coating type on the microstructure, mechanical properties and fatigue properties of FLW similar joints of DP980 was assessed. There existed spherical tempered martensite in the GA coated DP980 base metal (BM), most likely caused by the galvannealing process. Coating type did not present a noticeable effect on the microstructure of the welded zones. The GI coating, however, could evaporate violently during welding, resulting in high concavity and other welding defects which negatively affect the high-cycle fatigue property. Measures to mitigate the negative effects of the GI coating were discussed.
This paper investigates the gas jet wiping process, which is widely employed for controlling the ... more This paper investigates the gas jet wiping process, which is widely employed for controlling the final zinc-alloy coating thickness of a moving steel strip in the continuous hot-dip galvanizing process. In this study, large eddy simulation (LES) was employed to determine the effect of lower velocity symmetric auxiliary jets on main jet stabilization and coating thickness reduction during the gas jet wiping process. For validation purposes, experimental measurements of coating thickness were also carried out for the prediction of final coating thickness via a novel prototype multi-slot air knife used as the wiping actuator. Good agreement was found between the experimental measurements and model predictions for the coating weight, which also confirmed the applicability of the Elsaadawy et al. 1 model for the prediction of final coating weight for the multi-slot air knife geometry used. It was found that the jet flapping observed during single jet wiping could be prevented through use of the multi-slot air knife operating with lower velocity symmetric auxiliary jets (Re a /Re m = 0.45) situated on both sides of the main jet. The auxiliary jets modified the flow field in the main jet shear layer and diminished the formation of alternating vortices, which are the main cause of jet flow oscillations. As a result, a stabilized impinging flow with a longer potential core was found for the multi-slot jet configuration. This led to increased pressure gradient and increased shear stresses in the vicinity of the wiping region and, consequently, lower coating weights were obtained through use of the multi-slot air knife compared to the conventional single slot jet.
Continuous extruders have replaced the ram-press as the most common and economical means of produ... more Continuous extruders have replaced the ram-press as the most common and economical means of producing lead sheathed power cables. The intrinsic ability of the extruder to produce a significantly more uniform sheath composition should allow for a more dilute version of standard alloy compositions to be used, with equal or better performance of the sheath in service. No power cable
Abstract Grain boundary engineering (GBE) has lately been recognized as a viable approach to mani... more Abstract Grain boundary engineering (GBE) has lately been recognized as a viable approach to manipulate grain boundary characteristics to improve resistance against intergranular degradation. One of the most challenging intergranular degradation phenomena is liquid-metal-embrittlement (LME), where a reactive liquid metal penetrates along random grain boundary network. In contrast to random grain boundaries, special coincidence site lattice (CSL) boundaries has been shown to be resistant against the embrittlement. The present study investigates the feasibility of using a GBE technique to arrest LME in a Fe (FCC)-Zn couple. Two sets of low-strain-heat-treatment processing routes were used to optimize grain boundary characteristics based on: (a) Σ3 and Σ3n boundaries frequency, and (b) the material's texture and grain size evolution. The optimum characteristics resulted in significantly improved resistance against LME. The mechanism of the embrittlement arrest is discussed based on the random-grain boundary network continuity and the grain boundary triple junctions distributione.
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Papers by Frank Goodwin