Metals- Intro Flashcards
Name some primary shaping processes
Casting, pressure moulding, deformation processing, powder methods, special methods (lay-up, CVD, electroform)
Name some secondary shaping, joining and finishing processes
Machining, heat treat, joining (bolt, rivet, weld), finish (polish, plate, anodize, paint)
Common alloy of titanium
Ti-6Al-4V
Kroll process for making Ti
125MWh/ton to separate. Batch process over 5 days. Produce TiCl4 from TiO2 and Cl2.
Then TiCl4 + 2Mg -> 2MgCl2 + Ti
Chip out Ti sponge from reactor
Hunter process for making Ti
Mix TiO2 with Cl2 and C to make TiCl4
React with 4Na to form Ti and 4NaCl
FFC process for making Ti
Fray, Farthing and Chen. Ca metal dissolves in molten CaCl2 salt. This metal then reduces Ti oxides to Ti at the cathode. O2- ions go to graphite anode. In Ti crucible
Problems making Ti
Contact with air must be avoided while sponge is hot so no partial recombination with N. Molten Ti reacts with all ceramics as well as air. Must be melted under vacuum. Reheating furnaces must be H free and lubrication is necessary to avoid surface damage during hot working
Advantages of steel over Al alloys for automotive applications
Steels third to quarter of cost and production cost lower. More recyclable. Stiffer YM so less springback. Slight advantage in specific stiffness. Energy absorption in crash greater. Greater fatigue performance and endurance limit. More formable, harder, often magnetic (helps recyclability)
Advantage of Al over steel
Al third density of steel
Elongation-strength diagrams
Total elongation (%) vs tensile strength (MPa). Groups of different types of materials (often for advanced high strength steels AHSS) plotted of graph. Generally form curve from top left to bottom right getting close to origin. Known as banana diagrams. Want to get closer to top right ideally.
