Material Spotlight: Hastelloy C

In order for Hastelloy C to, in a wide range of environments that can be considered severe, offer superior corrosion resistance, tungsten has been added to a nickel-molybdenum-chromium super-alloy. How does this work? To maintain resistance against corrosion in as-sprayed structures, the low carbon content, during spraying, minimizes carbide precipitation. Chromium offers resistance against oxidizing media. Especially resistant is the nickel steel alloy (with molybdenum and high nickel contents) when it comes to crevice corrosion and pitting in reducing environments. And though Hastelloy C is undeniably the most widely used, there are numerous variations of the Hastelloy nickel alloy.

Hastelloy C Ratings for Machinability

This kind of wear, temperature, cobalt, and nickel-base corrosion resistant alloy, when machining, is classified as difficult down to moderate. It is important to realize, however, that the machining of these alloys is possible at satisfactory rates using production methods which are considered conventional. These alloys harden rapidly during machining. During cutting, they generate heat and may, as a result, weld to the surface of the cutting tool. Because of their high shear strengths, they will offer high resistance to metal removal. Consider, as much as possible, these key points during machining operations:

  • Particularly when using carbide tooling, lubricants such as soluble oils are both recommended and desirable.
  • In order to maintain a positive cutting action, use constant, heavy feeds. If the tool dwells in the cut because the feed has slowed, work hardening will occur. This results in the impossibility of close tolerances because tool life deteriorates.
  • For most machining operations, use positive rake angle tools. For heavy stock removal or intermittent cuts, tools with negative rake angles can be considered. For most applications, carbide tipped tools are encouraged. With lower production rates, high-speed tools can be utilized, and are in fact frequently used for intermittent cuts.
  • At all times, tools must be sharp. Rather than waiting until it’s necessary, change out tools at scheduled intervals. What is a dull tool? A tool with a wear land of 0.015 inches.
  • Minimize tool overhang. Both tool and workpiece should be held rigid.
  • As much as possible, the machine should be overpowered and rigid.

Material Wire Characteristics of Hastelloy C

With a melting point of 2500°F, a typical composition is made up of various percentages of the following: Nickel Balance, Si, Sulfur, Phosphorus, Vanadium, Carbon, Manganese, Cobalt, Tungsten, Iron, Chrome, and Molybdenum.

Some Characteristics of Hastelloy C

  • Though not all materials are capable of withstanding wet chlorine gas’s corrosive effects, Hastelloy C is capable of such.
  • It offers resistance to stress corrosion cracking and pitting and like types of corrosion.
  • In reducing environments, considerable corrosion resistance is provided by the molybdenum and high nickel contents.
  • Extreme resistance to cupric and ferric chlorides and like strong solutions involving oxidizing salts
  • In reducing environments, superior corrosion resistance

What Are Hastelloy C’s Applications?

Some typical applications can include the following:

  • Equipment used in processes that utilize acid catalysts or halide
  • Equipment that processes organic chloride
  • Sulfuric acid reactors
  • Equipment used in environments which contain sulfuric acids such as mixers, filters, heat exchangers, and evaporators
  • Flue-gas desulfurization plant equipment
  • Sour gas exposed components
  • Components used in the paper industry such as bleach plants and digesters
  • Equipment involved in food processing and pharmaceuticals
  • Equipment components used in processes involving petrochemical and chemical organic chloride

If you would like to find out more about Hastelloy C and how it can be applied to your business, please contact our experts at A&A Coatings. Experienced, knowledgeable representatives can help you with all of your thermal coating needs and more.

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