Material Selection and Classification: Why Expertise is Needed in Heat Treating?

23 November 2018

There’s no end to the number of metals out there, all of which serve different roles in countless applications. Selecting the materials, it’s up to a metallurgically talented sourcing expert to choose the material classifications that satisfy a customer’s demands. Heat treatment technology then further processes the metal so that it has all of the physical and mechanical characteristics it’ll need to serve its application.

A Blindingly Daunting Task 

How many properties can a metal sport when it is first sourced? To answer that question, think about the hundreds of ferrous and non-ferrous materials on the market. Some of them are more workable than others. Some alloys accept certain heat treatment processes, but other classifications refuse thermally active treatment, so the workpiece needs case hardening carburization or nitrocarburizing work. Elsewhere, a mild steel doesn’t possess enough carbon, chromium oxidization problems are plaguing the process, or its melting point doesn’t conform to a furnace’s current workpiece baking configuration. And that’s just the ferrous alloys. For non-ferrous metals, the issues multiply.

The Importance of Material Classification Expertise 

A capable material selection professional knows every aluminium series and every steel gauge. Metric or imperial, SAE standard or AISI, alloy connoisseurs know the features to highlight and the factors that’ll facilitate an expertly executed heat treatment run. Stainless steel or aluminium, tool steel or carbon strengthened alloy, even the many non-ferrous alloys, every metal is known to the sourcing professional. And not just by name, either. The composition, austenitic or martensitic microstructure, the forged characteristics and datasheet properties, they’re all intimately recognized by sourcing professionals.

Selected and Classified Alloys: It’s Half the Battle 

Correct, by buying in an alloy that serves a customer’s application specs, the heat treatment process is already halfway over. What remains is the engagement of a furnace/tempering procedure that will take the metal workpiece the rest of the way, all the way to the point that its operational parameters absolutely assure it’ll function in its eventual application. In service of this duty, coefficients of thermal expansion are assessed, melting points predetermined, and thermal conductivities recorded. At the end of the day, the primary goal here is to make sure the alloy selection and classification phase picks out an alloy that will be strong but not brittle, hard but not rigid, ductile, but not overly elastic, and environmentally capable but in no way chemically unstable.

To satisfy the above processing parameters, engineer expertise operates as a two-way street. On the one hand, the mechanical and physical specs are supplied. Meanwhile, the shortlisted selection candidates are picked out, but they can only be processed after the heat treatment facility delivers the right equipment. Given the go-ahead, the furnaces and tempering gear convert the raw workpieces into their final form.

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