Showing papers by "C.J. Van Tyne published in 2015"
TL;DR: In this paper, the effects of combined silicon and molybdenum alloying additions on microalloy precipitate formation in austenite after single and double-step deformations below the no-recrystallization temperature were examined in high-strength low-alloy (HSLA) steels with titanium and niobium.
11 citations
TL;DR: In this article, the authors used EDS to fabricate Ti-6Al-4V porous implant prototypes from atomized powders (100 150 μm), that were subjected to discharges of 0.75 to 2.0 kJ/0.7g-powder from 150, 300, and 450 μF capacitors.
Abstract: Electro-Discharge-Sintering (EDS) was employed to fabricate Ti-6Al-4V porous implant prototypes from atomized powders (100 150 μm), that were subjected to discharges of 0.75 to 2.0 kJ/0.7g-powder from 150, 300, and 450 μF capacitors. Both fully porous and porous-surfaced Ti-6Al-4V compacts with various solid core sizes were self-consolidated in less than 86 155 μsec. It is known that EDS can simultaneously produce the pinch pressure to squeeze and deform powder particles and the heat to weld them together. The formation of a solid core in these prototypes depends on the amounts of both the pinch pressure and heat generated during a discharge. The size of the solid core and the thickness of the porous layer can be successfully controlled by manipulating the discharge conditions such as input energy and capacitance.
6 citations
TL;DR: Electrical discharge using a capacitance of 450 μF at 7.0 and 8.0 kJ input energies was applied to mechanical alloyed Ti5Si3 powder and three stepped processes during an electrical discharge for the formation of nanostructured Ti5 Si3 compact are proposed.
Abstract: Electrical discharge using a capacitance of 450 μF at 7.0 and 8.0 kJ input energies was applied to mechanical alloyed Ti5Si3 powder without applying any external pressure. A solid bulk of nanostructured Ti5Si3 with no compositional deviation was obtained in times as short as 159 μsec by the discharge. During an electrical discharge, the heat generated is the required parameter possibly to melt the Ti5Si3 particles and the pinch force can pressurize the melted powder without allowing the formation of pores. Followed rapid cooling preserved the nanostructure of consolidated Ti5Si3 compact. Three stepped processes during an electrical discharge for the formation of nanostructured Ti5Si3 compact are proposed: (a) a physical breakdown of the surface oxide of Ti5Si3 powder particles, (b) melting and condensation of Ti5Si3 powder by the heat and pinch pressure, respectively, and (c) rapid cooling for the preservation of nanostructure. Complete conversion yielding a single phase Ti5Si3 is primarily dominated by the solid-liquid mechanism.
4 citations
TL;DR: In this article, two rolling simulations were conducted using a Gleeble 3500 to determine the no-recrystallization temperature, TNR on six microalloyed plate steels.
Abstract: Two rolling simulations were conducted using a Gleeble 3500 to determine the no-recrystallization temperature, TNR on six microalloyed plate steels. Double hit deformation tests and multistep torsion tests were performed on steels containing varying amounts of Nb, V, and Ti. TNR for the double hit deformation tests were determined by finding fractional softening using the 5 % true-strain method and the intersection of the sigmoidal fractional softening curve with 20 % fractional softening. TNR for the multistep hot torsion test were determined using a mean flow stress method and finding the intersection of the two linear regions. TNR values following multistep hot torsion testing were lower than values measured after double hit deformation testing. The decrease in measured TNR values for the torsion tests occurs from the inherent multiple deformations, resulting in refined grains and an increase in nucleation sites for recrystallization during the subsequent deformation steps; thus recrystallization can continue to occur at lower temperatures.
3 citations
TL;DR: In this article, the effect of the strength ratio extracted from an Archard model for wear is used to describe the wear rates expected in hot forging dies, where the work piece material is assumed to be AISI 1045.
Abstract: The effect of the strength ratio extracted from an Archard model for wear is used to describe the wear rates expected in hot forging dies. In the current study, the strength ratio is the strength of the hot forging die to the strength of the work piece. Three hot forging die steels are evaluated. The three die steels are FX, 2714, and WF. To determine the strength of the forging die, a continuous function has been developed that describes the yield strength of three die steels for temperatures from 600 to 700 °C and for times up to 20 h (i.e., tempering times of up to 20 h). The work piece material is assumed to be AISI 1045. Based on the analysis, the wear resistance of WF should be superior and FX should be slightly better than 2714. Decreasing the forging temperature increases the strength ratio, because the strength of the die surface increases faster than the flow strength of AISI 1045. The increase in the strength ratio indicates a decrease in the expected wear rate.
2 citations