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close this bookAnnealing, Hardening, Tempering - Course: Working Techniques of Heat Treatment of Steel. Instruction Examples for Practical Vocational Training
View the document(introduction...)
View the documentIntroductory Remarks
View the documentInstruction Example 16.1.: Spiral Spring
View the documentInstruction Example 16.2.: Marking and Riveting Tools
View the documentInstruction Example 16 3.: Flat Chisel and Cape Chisel
View the documentInstruction example 16.4.: Assembly Tools
View the documentInstruction Example 16.5.: Locksmith's Hammer
View the documentInstruction Example 16.6.: Testing Means

Instruction Example 16.6.: Testing Means

Practise the casehardening and tempering of testing means.


Prefabricated steel straightedges, back squares and centre squares made of unalloyed steel with a carbon content between about 0.1 and 0.15 %


Tools and devices

Controllable furnace with temperature gauge, quenching tank, fireproof inserts for sand charcoal filling, emery cloth

Auxiliary accessories

Charcoal (evenly cut into small pieces), clay, paper, quenching medium (heavily inflammable, heatproof lubricating oil), scouring cloth

Previous knowledge required

Manual working of materials

Sequence of operations


1. Prepare workplace Make working material available

Check for completeness

2. Wrap testing means into paper, lay into the insert with charcoal, cover the insert and lute by means of clay

3. Place insert into the furnace and heat; keep for about 5 hours

Phase 1
Starting temperature: 880°C to 920°C; Penetration depth of carbon: approx. 0.5 mm

4. Take the insert out of the furnace, unpack testing devices and let cool down in air

Phase 2

5. Harden the testing means at about 770°C

Phases 3 and 4

6. Temper the testing means at about 220°C

Phases 5 and 6

7. Clean the surfaces of the testing means

Testing Means