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Posted by Ali on May 18, 2003 at 13:08:58:

In Reply to: Re: nitriding of tool steel (hot work) posted by M.A.K. Babi on August 02, 2001 at 12:32:27:

: : What pre treatment, if any, is necessary to ensure a surface nitride formation an an H13 hot work tool steel? Can it be treated in the annealed condition? If not, why is it necessary to treat in the hardened and tempered condition?
: : If is treated in the annealed condition, what surface hardness can be expected at say 525C and what time at temperature to accomplish 0.2mm case.

: Dear Mr. Pye,
: If you wish to know how to produce a 'nitride' layer on the hot work tool steel,
: well the usual pretreatments like cleaning with solvents, controlled sputtering with argon:hydrogen in 50:50 ratio are needed. Epsilon type nitride structure can be created if the layer is desired to possess good tensile properties, which requires a leaner nitrogen:hydrogen mixture. Gamma prime layer can be produced by use of higher temperatures and longer durations, if only surface hardness is the main criterion. Surface hardness can be pretty high in HDS, going all the way up to 1200 Hv [200g]or even 1400 Hv depending upon plasma parameters.
: Yes, it can be treated in annealed condition. The same hardness as above can be achieved, since surface hardness is independent of the bulk or core hardness. However, a 'banana peel' effect is possible i.e. soft core surrounded by a harder shell. The user determines what he wants i.e. the application demands what sort of surface hardness and case depth should be achieved.
: From 480 to 520 degrees C is okay for all this, and a case depth of 0.2mm we are achieving regularly for several hot forging units here in six hours at these temperatures. We tend to go for lower temperatures generally. Deeper cases up to 0.45 mm have been achieved with longer durations. - maxbabi

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Subject:	Re: Re: Re: nitriding of tool steel (hot work)
Comments: : : : What pre treatment, if any, is necessary to ensure a surface nitride formation an an H13 hot work tool steel? Can it be treated in the annealed condition? If not, why is it necessary to treat in the hardened and tempered condition? : : : If is treated in the annealed condition, what surface hardness can be expected at say 525C and what time at temperature to accomplish 0.2mm case. : : Dear Mr. Pye, : : If you wish to know how to produce a 'nitride' layer on the hot work tool steel, : : well the usual pretreatments like cleaning with solvents, controlled sputtering with argon:hydrogen in 50:50 ratio are needed. Epsilon type nitride structure can be created if the layer is desired to possess good tensile properties, which requires a leaner nitrogen:hydrogen mixture. Gamma prime layer can be produced by use of higher temperatures and longer durations, if only surface hardness is the main criterion. Surface hardness can be pretty high in HDS, going all the way up to 1200 Hv [200g]or even 1400 Hv depending upon plasma parameters. : : Yes, it can be treated in annealed condition. The same hardness as above can be achieved, since surface hardness is independent of the bulk or core hardness. However, a 'banana peel' effect is possible i.e. soft core surrounded by a harder shell. The user determines what he wants i.e. the application demands what sort of surface hardness and case depth should be achieved. : : From 480 to 520 degrees C is okay for all this, and a case depth of 0.2mm we are achieving regularly for several hot forging units here in six hours at these temperatures. We tend to go for lower temperatures generally. Deeper cases up to 0.45 mm have been achieved with longer durations. - maxbabi
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