Inconel and titanium are both high-specification metals suitable for a wide variety of high-stress and corrosive applications. Though both have desirable physical and mechanical properties that make them suitable for extreme conditions, Inconel and titanium are very different metals. Here, we’ll look at the main properties, manufacturing concerns, and use cases that differentiate Inconel vs. titanium.

Inconel

Inconel is a trade name for a family of nickel-chromium superalloys made by Special Metals Corporation. It has an incredibly high tolerance for extreme temperatures and can withstand about 2,000°F (depending on the alloy) without losing strength. It also performs well in cryogenic temperatures.

In addition to its extreme temperature performance, Inconel has excellent mechanical properties at room temperature. Inconel 725, for example, has a tensile strength of up to 180 ksi—twice the strength of structural steel. Some Inconel alloys, such as Inconel 718, are precipitation hardened to increase their strength even further. Inconel is also highly resistant to corrosion, including oxidation, pitting, crevice corrosion, and corrosion cracking.

The properties of Inconel make it a valuable metal for the most demanding conditions. However, like most superalloys, it is significantly more expensive than common metals like steel, aluminum, and titanium.

Machining Inconel

The strength that makes Inconel such a valuable material for extreme conditions also makes it tough to machine. It’s exceptionally hard and is prone to work hardening during machining, which can damage cutting tools and deform the workpiece.

Stress-relieving Inconel through solutionizing before machining can help reduce surface hardness and limit work hardening, reducing the stress and wear on tooling. Ceramic tooling is recommended, as it is capable of fast, continuous cuts that minimize work hardening. It is also important to avoid pecking, which can increase work hardening.

Welding Inconel

Most Inconel is difficult to weld because the welds tend to crack. However, certain Inconel alloys are designed to be weldable. These are usually TIG (tungsten inert gas) welded with Inconel 625, the most weldable Inconel alloy, as a filler metal. While TIG welding doesn’t typically require a filler, it’s recommended for Inconel welding because of how hard it is to fuse two pieces without cracking them.

Inconel Applications

Because of its high chemical and temperature resistance, Inconel is ideal for a variety of aerospace, oil and gas, and marine applications. Some common use cases of Inconel include:

• Jet engine exhausts.
• Turbines.
• Exhaust couplings.
• Flare stacks.
• Natural gas piping.
• Marine propeller blades.
• Aerospace and marine fasteners.
• Heavy machinery parts.

Inconel is an ideal material whenever extreme temperature and corrosion resistance are needed, especially when high temperatures would degrade the strength and oxidation resistance of other metals.

Titanium

Titanium is an elemental metal with an exceptionally high strength-to-weight ratio, making it very useful for applications where minimizing weight is critical, like aerospace structural components. Titanium is about as strong as steel but only half the weight. However, these properties do come with a higher price tag than more common metals like aluminum and steel, though it’s generally much cheaper than Inconel.

Titanium does not react with oxygen and water at ambient temperatures. Like Inconel, titanium forms a passive oxidation layer on its surface that protects the material. This makes titanium extremely corrosion-resistant, even against strong acids like sulfuric and hydrochloric acids. Furthermore, titanium is also biocompatible and non-toxic, so it’s used for many medical applications.

Titanium is available in both commercially pure and alloyed grades. The most common alloy, Ti 6Al-4V, is alloyed with aluminum and vanadium and accounts for about half of all titanium used globally. This and other titanium alloys are designed to be harder, stronger, and/or easier to work than pure titanium. Commercially pure (CP) titanium is softer and more ductile than titanium alloy, but its corrosion resistance is outstanding.

Machining Titanium

The properties that make titanium such a useful metal also make it very difficult to machine. Like Inconel, titanium is susceptible to work hardening. CP titanium is also very gummy when machining and forms long, continuous chips that can interfere with the cutting tool. This characteristic also makes it susceptible to galling. This can be reduced by using lots of high-pressure coolant to remove chips as soon as possible and keep the tool flutes clear.

When machining titanium, avoid interrupted cuts and keep the tool in motion at all times when contacting the workpiece. Excessive contact will cause the tool to rub, creating excess heat that leads to work hardening. Machining at a lower speed and higher feed rate can significantly reduce heat generation.

While Inconel is extremely hard and rigid, titanium is much more flexible, so workpieces require a secure grip and as rigid a machine setup as possible. Titanium and its alloys are very elastic, which causes springback and chatter during machining and can result in a poor surface finish.

Welding Titanium

Titanium and its alloys are readily weldable. The techniques and equipment for welding titanium are similar to those for other high-specification metals, such as stainless steel or nickel-base alloys. Titanium, however, requires more careful attention to cleanliness and inert gas shielding than other metals. Contamination by air can ruin titanium welds.

Titanium Applications

The mechanical properties of titanium, particularly its strength-to-weight ratio, are very useful in the aerospace and automotive industries. Ti 6AL-4V accounts for almost half of all alloys used in aerospace applications. It’s also commonly used in the medical industry due to its superior corrosion resistance and biocompatibility.

Some common uses of titanium include:

• Aircraft engines and frames.
• Armor plating.
• Naval ships.
• Spacecraft.
• Missiles.
• Landing gear.
• Exhaust ducts.
• Artificial joints.
• Hardware for setting or repairing bones.
• Implanted medical devices.
• Sporting equipment.
• Bicycle frames.

Inconel and Titanium

Industrial Metal Service specializes in supplying Inconel, titanium, steel, aluminum, and other metals to machine shops, fabricators, and manufacturers in the San Francisco Bay Area. We also ship nationwide with no minimum order quantity. Our San Jose warehouse is stocked with an extensive inventory of Inconel and titanium alloys, including both new metals sourced from U.S. mills and verified metal remnants that offer considerable savings.