Insights & Events

Enhanced property treatments: Ordinary alloys punch above their weight

Since the dawn of the industrial revolution, manufacturers have chased the innovation trifecta of better quality, higher speed and lower cost. Achieving all three is the cornerstone of profitability in any industry.

And it’s much easier said than done.

So how can manufacturers make sure they’re not leaving any innovations on the table? One way is to partner with a heat treater that develops innovative processes that allow parts to punch above their weight.

Enhanced property thermal process SAE 4140

The best way to show what we mean is by discussing a real-world example: How we developed a family of enhanced property processes that allow manufacturers to replace costly high-performance materials with much more cost effective 4140 steel. In this discussion, we highlight tests we conducted comparing enhanced property 4140 steel to vacuum arc re-melted (VAR) 4340.

Vacuum arc re-melted 4340 vs. 4140 steel

4340 steel is a low-alloy formula featuring nickel as well as some chromium and molybdenum. It is tough and strong as heat treated, characteristics which bode well for use in automotive applications such as axle shafts and crank shafts as well as high-performance brackets and bolts used in many industries.

Critical parts such as these are subject to intense stress over long periods of time. VAR proved to be an ideal method to improve the mechanical properties of 4340 steel by eliminating impurities that accompany the traditional continuous cast manufacturing method.

VAR 4340 ingots are also more chemically homogenous, further increasing their toughness. The chart below compares the chemistries of 4140 and 4340.

SAE 4140 and vacuum arc re-melted SAE 4340 composition chart

While the formulas are very similar, the addition of nickel imparts much higher performance to 4340. It also costs a lot more.

4140 steel features added chromium and molybdenum, which impart improved hardness penetration, uniform hardness and increased strength. It’s also easy to machine, making it very versatile.

Accordingly, 4140 steel is widely used across the industrial spectrum. But for critical shaft components or other parts under high stress, it isn’t normally ideal. While vacuum arc re-melting is an expensive, time-consuming process, VAR 4340 steel is specified for some stressful service applications because it can handle the strain but is still less expensive than other high-performance alloys.

Paulo’s enhanced property process family

This got our metallurgy team thinking. Manufacturers could save time and money if lower-cost materials like 4140 exhibited the enhanced mechanical properties of VAR 4340 or other similar alloys.

It motivated us to develop a family of processes that would overcome one of metallurgy’s general rules: As strength increases, ductility decreases. Our goal was to enhance both strength and ductility, and we developed treatments featuring both gas and oil quenches to do it.

Gas quench processes

Using vacuum furnaces, we have much greater process control. We can design very specific thermal cycles without worrying about part surface chemistry changes.

In our enhanced property treatments, parts are austenitized under vacuum. Then, the chamber is backfilled with inert gas. The gas is heavily agitated by powerful motors. The chart below compares a sample 4140 part treated this way versus a conventionally heat treated 4140 part and a VAR 4340 part.

Enhanced gas quench thermal process SAE 4140 comparison

Oil quench processes

Controlling surface carbon content is critical to achieving desired mechanical characteristics via oil quench treatments.

This close control is the foundation of our enhanced property oil quench treatments. We complete the treatments in our integral quench furnaces. Our testing shows key mechanical qualities like strength, ductility and impact resistance are enhanced.

Comparing enhanced oil quench SAE 4140 and vacuum arc re-melted SAE 4340

Will our enhanced property processes work for your parts?

Good candidates for our enhanced property family of processes are parts requiring good ductility and fracture toughness with strength levels above around 200 ksi. We typically treat the following parts with enhanced property processes:

  • Tooling
  • Hand tools
  • Automotive OEM components
  • Aftermarket automotive and automotive racing parts
  • Agricultural parts
  • Firearm components

The benefits of specifying these processes are compelling: OEMs and their suppliers are cutting raw material costs and streamlining production operations. Their supply chain risk is reduced and they’re poised for strong future growth.

We understand the pressures modern manufacturers are under. We know that constant innovation is key to staying profitable. To learn more about whether we can help take your production to the next level, let’s talk.

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