Specialized Turning Blog

What Should I Know About Machining Hastelloy?

Posted by Chip Holm on May 8, 2019 11:12:15 AM

Considerations of Costs and Qualities of Hastelloy

It’s well-known that Hastelloy, also known as C276, is among the most difficult materials to work with—due to, in part, the toll it takes on the tooling but also its heat- and-corrosion resistance properties. This material is in high demand in industries like pharmaceutical, petrochemical, chemical, oil and gas, nuclear, pollution control, etc.,—anywhere there is extreme heat and a caustic environment, so there is good reason to discuss why it is sought after.

Let's take a quick look at Hastelloy’s most valuable attributes that show why it is so versatile.

Attributes of Hastelloy:

  • Resistance to acids, such as sulfuric, machining hastelloyphosphoric, nitric, and hydrochloric
  • Almost completely free from chloride induced stress corrosion cracking
  • Excellent mechanical properties at both extremely low and extremely high temperatures
  • Outstanding resistance to pitting, crevice corrosion and intercrystalline corrosion
  • High resistance to oxidation at elevated temperatures

Hastelloy C-276® is a nickel-molybdenum-chromium alloy with excellent corrosion resistance in severe environments. The high nickel and molybdenum contents make the nickel steel alloy especially resistant to pitting and crevice corrosion in reducing environments while chromium conveys resistance to oxidizing media. Although there are several variations of the Hastelloy nickel alloy, Hastelloy C-276 is by far the most widely used.

High Price of Machining Hastelloy

At Specialized Turning, we are well-versed in how to handle this tough metal and maximize our machining efficiency, so we wouldn’t call it high-maintenance, exactly—but it is close, when it comes to qualifying how Hastelloy is to work with. A few factors that contribute to the high cost of Hastelloy involve the high amount of energy required to separate the metal. Once one the tooling floor, machining is costly. When machining Hastelloy, we must consider some tough restrictions on machining parameters that can affect:

  • Metal removal rates
  • Surface finish quality
  • Dimensional accuracy
  • Tool life (premature tool change vs. expense of regrind)
  • Run time (as compared to machining other types of alloys)
  • General maintenance of machines

Hastelloy’s Machinability

hastelloy's machinabilityWhile finished precision Hastelloy components have may attractive features, some of the properties of Hastelloy that impact its performance when being machined give credence to its classification as being tough to work with.

Factors that influence Hastelloy’s machinability are:

  • Poor conduction of heat, effectively concentrating the heat on the cutting edge and tool face creating excessive wear
  • Chemical reactivity, which causes galling, welding, and smearing, all leading to compromising the cutting tool
  • Precise speeds and feeds required to mitigate Hastelloy’s and hard chromium qualities that tend to distort key features, especially any thin cross-sections of the part. The exact speeds and feeds are usually specific to the geometry of the part, sharp cutting tools, and general system rigidity

See How We Work with Hastelloy!

At Specialized Turning, we are experts in machining Hastelloy alloys to produce the best possible quality and value. We use only state-of-the-art tooling geometries and coatings to ensure the most economical stock removal rates at highest speeds possible for economical machining. With our extensive inventory of tooling upfront costs and order processing, costs are minimized.

Let’s talk about your Hastelloy needs. We’d love to get the conversation started. Contact us today!

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Topics: hastelloy, hastelloy machining, Qualities of Hastelloy