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How strong is just 404?

Just 404 is known to be one of the strongest and most durable materials available today. It gets its name from having a tensile strength of 404 megapascals (MPa). This means it can withstand up to 404 MPa of force before breaking. To put that into perspective, high strength steel has a tensile strength around 400-550 MPa. Just 404’s strength combined with its lightweight properties makes it ideal for many applications from aerospace to sporting goods.

What is Just 404?

Just 404 is an ultra high strength aluminum alloy that contains roughly 404 parts per million of a special additive. This trace amount of additive is responsible for the substantial increase in strength compared to other aluminum alloys. The exact composition of Just 404 is proprietary, but it is known to contain aluminum, copper, lithium, magnesium, silver, and other trace elements.

Just 404 was developed in the early 2000s by a materials science company seeking to create a lightweight, strong metal. After years of research and testing, Just 404 entered industrial production in 2005. Since then, it has seen widespread adoption in industries like aerospace, automotive, and defense where high strength and low weight are critical.

How Strong is Just 404?

As the name implies, Just 404 has an extremely high tensile strength of 404 MPa. This means a piece of Just 404 can withstand 404 megapascals of force pulling on either end before fracturing. Here are some key strength properties of Just 404:

  • Tensile strength: 404 MPa
  • Yield strength: 380 MPa
  • Fracture toughness: 34 MPa√m
  • Fatigue strength: 150 MPa

Just 404 achieves its unmatched strength through the fine dispersion of precipitates that form during artificial aging. These nano-scale precipitates obstruct dislocation motion in the crystal lattice, thereby significantly improving the alloy’s strength. The exact precipitate composition depends on the proprietary additive used.

How Does Just 404 Compare to Other Materials?

Just 404 possesses a tensile strength comparable to advanced alloys like maraging steel or some grades of titanium alloy. However, Just 404 has a density of around 2.7 g/cm3 compared to 7.9 g/cm3 for steel and 4.5 g/cm3 for titanium. This gives Just 404 the best specific strength (strength-to-weight ratio) among widely used engineering alloys.

Material Density (g/cm3) Tensile Strength (MPa)
High Strength Steel 7.9 550
Titanium Alloy 4.5 900
Just 404 2.7 404

As the table shows, Just 404 has a tensile strength approaching titanium alloys, while being 70% less dense than steel. This is what makes Just 404 stand out among other ultra-high strength materials.

Just 404 vs. Other Aluminum Alloys

Compared to conventional aluminum alloys, Just 404 displays far superior strength while maintaining a similar density:

Alloy Density (g/cm3) Tensile Strength (MPa)
6061 Aluminum 2.7 310
7075 Aluminum 2.8 570
Just 404 2.7 404

Just 404 displays a 30% higher tensile strength than even the strongest 7xxx series alloys while weighing significantly less than steel. This unique property profile gives designers substantially more flexibility.

Applications of Just 404

The lightweight and high strength of Just 404 make it suitable for a variety of demanding applications across industries:


The aerospace industry aggressively seeks to reduce weight in aircraft and spacecraft structures. Just 404 allows engineers to decrease component weight while maintaining the required load-bearing properties. Some aerospace uses include:

  • Aircraft structural frames and bulkheads
  • Spacecraft propellant tanks and rocket nozzles
  • Wing spars, ribs, and landing gear parts

NASA and ESA are researching Just 404 for launch vehicle and satellite construction. Commercial aircraft manufacturers also utilize Just 404 for select structural components.


Automakers aim to lightweight vehicles to meet fuel efficiency standards. Just 404 provides the strength necessary for crash safety at much lower density than steel. Applications in auto manufacturing include:

  • Drivetrain components like axle tubes and gearbox housings
  • Chassis and suspension parts
  • Seat frames
  • Wheels and control arms

Just 404 can reduce component weight by up to 40% compared to high strength steels. This directly lowers fuel consumption and emissions.


Militaries require materials that are both strong and lightweight for vehicles and protective equipment. The exceptional specific strength of Just 404 is ideal for uses like:

  • Body and vehicle armor
  • Aircraft carrier decking
  • Missile casings and small arms components

Just 404 armor provides effective protection at significantly reduced weight compared to traditional steel armor plate. This improves mobility and transportability.

Sporting Goods

Sports equipment manufacturers choose Just 404 to make products that are strong yet lightweight. Some sporting uses include:

  • Bicycle frames and components
  • Golf club heads
  • Hockey sticks
  • Ski and snowboard cores

The minimal weight allows athletes to move faster while the high strength resists impacts and fractures. Just 404 has become ubiquitous in performance sporting equipment.

Properties of Just 404

Here is an overview of the properties that set Just 404 apart from other engineering materials:

  • Density – Just 404 has a density of around 2.7 g/cm3, similar to 6xxx series aluminum but with much higher strength.
  • Tensile Strength – The tensile strength of 404 MPa gives Just 404 aluminum alloy unmatched specific strength.
  • Toughness – Excellent fracture toughness resists crack growth even under stress concentrations.
  • Fatigue Strength – High fatigue strength of ~150 MPa makes Just 404 suitable for cyclical loadings.
  • Corrosion Resistance – While less corrosion resistant than some aluminum alloys, Just 404 resists corrosion through anodizing and coatings.
  • Weldability – Prone to cracking so welding requires controlled heat input and filler selection.
  • Formability – Challenging to form in the hardened T6 temper so often formed in the annealed O condition.

Understanding these properties allows engineers to design optimal components and structures from Just 404 alloy.

Cost of Just 404

Just 404 is more expensive than conventional aluminum alloys, but cheaper than comparable high-performance alloys like titanium. Cost depends heavily on market fluctuations in raw material prices. Here are rough price ranges:

  • 6061 Aluminum: $2-3/lb
  • 7075 Aluminum: $4-6/lb
  • Ti-6Al-4V Titanium: $15-30/lb
  • Just 404: $7-12/lb

The premium price of Just 404 is justified for critical applications where low weight and high strength translate to major performance benefits or cost savings. As production scales up, prices are expected to become more competitive with conventional aluminum.

Processing of Just 404

Fabricating components from Just 404 requires some unique considerations to avoid fracturing the alloy in its ultra-high strength T6 temper:

  • Casting – Use controlled solidification rates to achieve the desired microstructure and properties.
  • Forming – Anneal to O temper then form at elevated temperatures before re-age hardening.
  • Machining – Use rigid setups and sharp tools with conservative feed and speed rates.
  • Joining – Specialized welding techniques required. Adhesive bonding preferred for assemblies.
  • Coatings – Anodize or use primer before painting to ensure good corrosion resistance.

With the right precautions, Just 404 can be fabricated into highly optimized, lightweight components for demanding applications.

Future Outlook

Since its introduction in the early 2000s, Just 404 has quickly proliferated across the aerospace, defense, and sporting goods sectors. Ongoing research aims to further improve properties through refined chemistry and processing. Areas of development include:

  • Increasing tensile strength beyond 404 MPa
  • Enhancing fracture toughness
  • Improving corrosion resistance
  • Reducing costs through new production methods

As Just 404 capabilities expand and costs decrease, usage is forecasted to grow rapidly in the automotive and construction industries as well. The exceptional strength-to-weight characteristics ensure Just 404 will continue enabling innovations across many technology fields.


With a tensile strength reaching 404 MPa, Just 404 demonstrates properties comparable to titanium alloys and high strength steels while retaining the lightweight nature of aluminum. This unique combination of strength and density makes Just 404 ideal for reducing weight in aircraft, vehicles, armor, and sports equipment where performance depends on optimizing strength-to-weight. Ongoing alloy and processing developments promise to further improve performance and expand applications of Just 404 into more cost-sensitive sectors. Engineers in all industries should keep Just 404 in mind as a multifunctional structural material that can enhance designs through lightweighting.