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CASE HARDENING OF MILD STEEL

V. Ryan 2005 - 2009

 

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Case hardening is a simple method of hardening steel. It is less complex than hardening and tempering. This techniques is used for steels with a low carbon content. Carbon is added to the outer surface of the steel, to a depth of approximately 0.03mm. One advantage of this method of hardening steel is that the inner core is left untouched and so still processes properties such as flexibility and is still relatively soft.

STAGE ONE:

The steel is heated to red heat. It may only be necessary to harden one part of the steel and so heat can be concentrated in this area.

   

STAGE TWO:

The steel is removed from the brazing hearth with blacksmiths tongs and plunged into case hardening compound and allowed to cool a little. The case hardening compound is high in carbon.

   

 

   

STAGE THREE:

The steel is heated again to a red colour, removed from the brazing hearth and plunged into cold, clean water.

 

The steel rod should now have a hardened outer surface and a flexible, soft interior. The process can be repeated to increase the depth of the hardened surface.

QUESTIONS:

1. Draw a sequence of diagrams representing the case hardening of mild steel.

   
 
   

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