Titanium vs Stainless Steel: CNC Machining Guide

Overview

Titanium and stainless steel are both strong, corrosion-resistant metals. Engineers often debate which one to use. The answer depends on your part's weight limit, operating environment and budget.

Ti-6Al-4V is the most common titanium alloy. It offers a rare mix of high strength and low weight. On the stainless steel side, three grades dominate CNC work: SS 304 (the general-purpose workhorse), SS 316 (the marine and chemical champion) and SS 17-4 PH (the high-strength option).

This guide gives you the real numbers. No guessing. By the end, you will know exactly which metal fits your next project.

Properties Comparison Table

All values are typical for wrought, heat-treated stock. SS 17-4 PH values are for Condition H900 (peak strength).

Weight Comparison

Weight is where titanium wins big. Ti-6Al-4V weighs 0.160 lb/in³. All three stainless grades weigh about 0.285–0.289 lb/in³. That means a titanium part is roughly 45% lighter than the same part in stainless steel.

For aerospace, that weight savings translates directly into fuel savings. Every pound removed from an aircraft saves about $1,000 per year in fuel over its lifetime. That is why titanium dominates in jet engines, airframes and spacecraft.

For medical implants, lighter means more comfortable for the patient. A titanium hip stem weighs far less than a stainless steel one, which reduces stress on the surrounding bone.

Corrosion Resistance

Both metals resist corrosion, but they handle different environments.

Titanium (Ti-6Al-4V)

Titanium forms a tough oxide layer that protects it from saltwater, chlorine, wet chlorine gas and most organic and inorganic acids. It does not pit, crevice-corrode, or stress-corrode in seawater. That makes it the standard for naval hardware, desalination plants and chemical reactors.

SS 304

SS 304 handles mild environments well. It works for food equipment, kitchen hardware, architectural trim and indoor industrial parts. But it can pit in chloride-rich environments like coastal air or pool chemicals.

SS 316

SS 316 adds molybdenum to the mix, which gives it much better chloride resistance than SS 304. It is the standard for marine fittings, pharmaceutical equipment and chemical tanks. It can handle most saltwater environments, though concentrated chlorides at high temperatures can still cause pitting.

SS 17-4 PH

SS 17-4 PH has good general corrosion resistance, roughly on par with SS 304. It is not as strong as SS 316 in marine or chemical environments. Its main selling point is strength, not corrosion resistance.

Biocompatibility

Biocompatibility matters for any part that touches the human body. Here is how each metal stacks up:

• Ti-6Al-4V: The gold standard. It is used for hip replacements, spinal fusion cages, bone screws, dental implants and pacemaker housings. The body does not reject it and bone actually grows onto its surface (osseointegration).
• SS 316L: The low-carbon version of SS 316 is used in temporary implants like bone plates and surgical screws. It is not ideal for permanent implants because nickel can leach over time and cause reactions in sensitive patients.
• SS 304 and SS 17-4 PH: Neither is considered biocompatible for implant use. Both contain too much nickel for long-term body contact.

If your part will live inside a person, Ti-6Al-4V is the clear winner. For parts that only touch skin briefly (surgical handles, instrument housings), SS 316L works fine.

Cost Comparison

Here is a realistic cost breakdown for a simple turned shaft (1.5" diameter x 4" long) at a quantity of 25 parts:

Ti-6Al-4V parts cost roughly 3 to 6 times more than equivalent stainless steel parts. The gap comes from expensive raw material, slower cutting speeds and faster tool wear. If your part does not need titanium's weight or corrosion advantages, stainless steel saves you a lot of money.

For a full breakdown of how shops calculate these numbers, read our guide on how to read CNC shop quotes.

When to Use Each Metal

Choose Ti-6Al-4V When:

• Weight savings are critical (aerospace, defense, drones, wearable devices).
• The part will sit in saltwater, concentrated acids, or wet chlorine gas.
• You need a permanent implant or long-term body-contact device.
• Operating temperatures exceed 600 °F.
• You need a non-magnetic, high-strength metal.

Choose SS 304 When:

• The part is for food processing, kitchen equipment, or general industrial use.
• Cost matters and the environment is mild (no saltwater, no strong acids).
• You need a widely available, easy-to-source material.

Choose SS 316 When:

• The part will face marine, pharmaceutical, or chemical environments.
• You need better chloride resistance than SS 304 but cannot justify titanium costs.
• Temporary medical devices or food-grade equipment are involved.

Choose SS 17-4 PH When:

• You need very high strength (145 ksi tensile) without paying for titanium.
• The part is an aerospace fastener, valve stem, or nuclear component.
• Heat treatability is important for hitting specific hardness targets.
• Magnetic properties are acceptable or even desired.

Not sure which grade fits your project? Upload your CAD file and our engineers will recommend the best material for your application, budget and timeline.

Frequently Asked Questions

RivCut Engineering Team

Reviewed by Jimmy Ho, Founder & CEO

Our team combines 30+ years of CNC machining expertise across aerospace, defense, medical and automotive industries. We write what we know, from the shop floor.