CARBONITRIDING OF POROUS P/M BLANKS

With increasing total blank porosity and decreasing powder particle size the fraction of open pores grows and consequently so does the thickness of the carbonitrided layer. Carbonitride zones were found to form on blank surfaces at a treatment temperature of 970°K. During short-time heating of carbonitrided blanks for HF their diffusion layers were found to undergo partial denitriding and decarburization. It was established that to preserve the quality of the carbonitrided layer it is necessary to perform heating for a short time at a low temperature and also employ a protective atmosphere.