Titanium Connecting Rod

1. What is titanium alloy? 

Titanium alloy is formed by mixing titanium with various alloying elements. The addition of alloying elements can produce a wide range of different physical and mechanical properties. Titanium is commonly classified as unalloyed, alpha and near-alpha, alpha-beta, and metastable beta. Titanium Alloy Connecting Rods Unalloyed titanium, generally known as commercial purity (CP) titanium, is the weakest but most corrosion-resistant version of the metal. The interstitial elements oxygen and nitrogen greatly strengthen “pure” titanium. CP titanium takes advantage of interstitial hardening from oxygen and effects of small additions of other elements (e.g., iron and palladium) to provide for various grades of the metal to fit a variety of applications. CP titanium is selected for its excellent corrosion resistance in applications where high strength is not required. Yield strengths may vary from about 170 MPa to 480 MPa.

Alpha and near-alpha alloys are alloys with relatively large amounts of alpha stabilizers and low concentrations of beta stabilizers. Their microstructures are less prone to decomposing at high temperatures. The high aluminum content of these alloys assure excellent strength characteristics and oxidation resistance at elevated temperatures (316-593°C). Alpha alloys cannot be heat-treated to develop higher strength since they are single-phase alloys. In short, alpha alloys have excellent high-temperature strength and oxidation resistance, but room-temperature strength is lower than other titanium alloys.

Beta alloys have a single beta phase. The beta phase is a metastable phase; cold work at ambient temperature or heating to a slightly elevated temperature can cause partial transformation to the alpha phase. Quenching and aging can be used to increase the room-temperature strength, to about 1372 to 1666 MPa. In short, beta alloys have high room-temperature strength but cannot be used in high-temperature environments.

Alpha-beta alloys have two phases at ambient temperature. They have good structural stability, ductility, plasticity, and high-temperature deformation properties, and can be further improved by forging, quenching, and aging. Solution treating and aging can be used to develop the strength of these alloys. Heat treatment can increase the strength of alpha-beta alloys (e.g., Ti-6Al-4V) by 30%-50% or more. They can be used above 350°C, and their thermal stability is similar to that of alpha alloys. In short, alpha-beta alloys have more balanced performance.

2. Ti-6Al-4V vs. 4340 

Ti-6Al-4V developed in the United States in the 1940s, is one of the most widely used titanium alloys. It is an Alpha-beta type containing 6 wt% Al and 4 wt% V. The density of Ti-6Al-4V is 4.51 g/cm³, approximately 60% of the density of 4340. The specific strength approximate is 160% of 4340. The tensile strength of this particular Ti-6Al-4V is 1024 MPa, elongation is 10.4%, and reduction of area is 29.7%. These values are close to that of 4340.

3. Advantages of titanium alloy connecting rods

3.1 Material: Titanium alloy connecting rods are made from forged plates as raw material and are machined into final products. Compared to casting and powder, forging can make the microstructure and distribution of elements more uniform and reduce gaps among microstructures. The plates are thoroughly inspected for chemical content, mechanical properties, and ultrasonics to ensure excellent quality.

3.2 Weight: Titanium alloy rods are 30% lighter than steel rods.

3.3 Bushings: All BW titanium rods install AMPCO45 bushings.

3.4 Special tap with coating for threading titanium rods only.