Question 1

How much does tool steel shrink or grow during hardening?

Accepted Answer

Most tool steels grow 0.0005–0.002 inches per inch during hardening due to the transformation of ferrite to martensite. High-speed steels (M2, M42) may shrink slightly. Always consult the steel manufacturer's data sheet for your specific grade, as growth varies with hardening temperature and section thickness.

Question 2

Can I machine tool steel in the hardened state?

Accepted Answer

Yes, using CBN or ceramic tooling for turned surfaces and EDM for complex geometries. Hard machining (45–68 HRC) is an established process for mold and die manufacture. Modern machines with sufficient rigidity can achieve surface finishes below 16 μin Ra on hardened tool steel.

Question 3

Does stress relief annealing reduce distortion?

Accepted Answer

Yes. Stress relief annealing at 600–700°C before rough machining reduces residual stresses from mill processing. Rough machine, then stress relieve again at 600°C before finish machining and heat treatment. This double stress relief cycle can reduce final distortion by 50–70%.
⚡ Calculated for Carbide-Tooling.com High-Performance Series. View Catalog →

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