Titanium alloy for bicycles
Titanium bicycle has the advantages of being lightweight, high strength, good corrosion resistance, and fatigue resistance. Since the mid-1980s, titanium bicycles have developed, which has promoted the application of titanium materials. For example, ANCOTECH and HAYNES INTERNATIONAL, three companies producing Ti3Al-2.5V pipes in the United States, And SANDVIK SPECIAL METALS have turned to the bicycle industry.
Ti-3Al-2.5V and Ti-6Al-4V are the most commonly used titanium alloys for bicycle frames in a choice of material selection. Compared with other titanium alloys, Ti-3Al-2.5V has the greatest advantage of high yield strength, good process plasticity, and good welding performance, but its disadvantage is the high price. Although it is developed for aircraft hydraulic systems, it meets the requirements of the bicycle market for material properties due to its good formability, corrosion resistance, elongation, high fatigue strength, and low density.
In the past few years, the frame made of industrial pure titanium arm and non-aviation Ti-3Al-2.5V (sports grade) titanium alloy is very popular. Ti-6AL-4V is the most mature titanium alloy material with good comprehensive mechanical properties and the most complete performance data. It has good process plasticity and superplasticity, and is suitable for various pressure processing and forming. It can also be welded and machined in a variety of ways, but its formability, weldability, and machinability are inferior to the former.Ti-6Al-4V is also attractive for making frames. Its modulus and strength are slightly higher than Ti-3AL-2.5V, but it is difficult to process it into a small-diameter bicycle frame pipe. The crankshaft positioner, pedal, handlebar, and other bicycle parts connected to the frame are mostly made of Ti-6Al-4V.
Due to the high smelting cost of titanium alloy and the high content of molybdenum, vanadium, chromium, niobium, and other expensive elements, the product price is on the high side; In addition, due to the active chemical properties of titanium alloy, the plastic forming such as extrusion, bending and welding are easy to absorb hydrogen and oxygen, which degrades the product performance, and the formability, weldability, and machining performance are also poor, which greatly increases the process cost, which restricts the popularity of titanium alloy frame. Now some foreign material manufacturers are committed to developing new titanium alloy materials with low cost and easy processing.
Titanium alloy for racing (automobile/motorcycle)
Titanium is an ideal material for automobile structural parts. Connecting rods, valves, silencers, exhaust pipes, hubs, and other components are suitable for manufacturing with titanium alloys. For example, the exhaust system of Coryete Z06 model launched by General Motors Corporation of the United States uses titanium silencers, the Lupo FSI model of Volkswagen of Germany uses titanium springs, and the titanium consumption of Japanese cars has reached the level of 200~300t/a.In the past, 60 million cars were produced annually in the world. If 50% of cars used 1kg of titanium material each, the demand for titanium materials in the world would increase by more than 60%. As early as 20 years ago, racing engines had reduced the weight of titanium valves and titanium connecting rods.
As the connecting rod of the racing engine is a load part that bears strong impact and high dynamic stress, its lightweight can reduce torque and power output, improve the impact of dynamic balance, and reduce running noise, vibration, and fuel consumption. In addition to the commonly used hot forging process, the titanium alloy connecting rod made by powder metallurgy (forging) is an advanced manufacturing technology with high material utilization rate, excellent performance, clean machining, and fluctuation of connecting rod quality. At present, the powder forging technology of connecting rods abroad has been mature. In 1995, the powder-forged connecting rods of Jaguar engine AJ-8V produced by Bridgefoot Engine Factory in the UK was only 605g in quality Compared with ordinary die forgings, the material utilization ratio increased from 48.3% to 95.9%.
