Damage Mechanisms in Salt Bath Nitro-carburised and Plasma Nitrided Hot Forging Dies of H11 Tool Steel

Access this Article

Search this Article

Author(s)

    • DEVI M. Uma
    • Formerly at Research and Development Division, Tata Iron & Steel Co. Ltd.

Abstract

Studies have been made to compare the effect of salt bath nitro-carburising and plasma nitriding treatments, on the working life of hot forging dies made of H11 grade of tool steel. Working life of the surface modified dies, that are used for the production of bearing races by high speed closed die forging, was evaluated in the real plant operation. Salt bath nitro-carburised tools are found to give an average life of 12 000 races with a very wide variation between 1 000 to 35 000 races. In sharp contrast, plasma nitrided tools showed a consistent two to four fold higher life than the salt bath nitro-carburised tools. The surface of worn out dies was examined by scanning electron microscopy (SEM) to understand the nature of damage processes involved in the dies subjected to two different surface treatments. Fatigue cracks, resulting from cyclic thermal and mechanical loading during operation, are the dominant modes of damage in the case of salt bath nitro-carburised as well as plasma nitrided dies. The severity of die damage by mechanical fatigue was more in the salt bath nitro-carburised dies. Abrasive wear due to micro cutting was observed to result in significant damage of the salt bath nitro-carburised die. Die damage due to micro cutting was not observed in the plasma nitrided dies. However, signatures of chipping and plastic deformation were noticed at few locations. The results obtained on service life and wear mechanisms after the two different surface treatments are examined in the light of the characteristics of the modified surfaces.

Journal

  • ISIJ International

    ISIJ International 42(5), 527-533, 2002-05-15

    The Iron and Steel Institute of Japan

References:  21

  • <no title>

    THOMAS A.

    Tribology in Iron and Steel Works 135, 1970

    Cited by (1)

  • <no title>

    ASTON J. L.

    J. Iron Steel Inst. 207, 167, 1969

    Cited by (1)

  • <no title>

    LINDER H.

    Werkstattstechnik 53, 913, 1963

    Cited by (1)

  • <no title>

    SUMMERVILLE E.

    Mater. Des. 15, 289, 1995

    Cited by (1)

  • <no title>

    THOMAS A.

    Wear Tests on Die Materials, 1965

    Cited by (1)

  • <no title>

    Felder E.

    Tribol. Int. 13, 61, 1980

    Cited by (1)

  • <no title>

    VANKATESAN K.

    Wear 203-204, 129, 1997

    Cited by (1)

  • <no title>

    SEIDEL R.

    New Materials, Processes, Experiences for Tooling 467, 1992

    Cited by (1)

  • <no title>

    ROOKS B. W.

    Met. Technol. 1, 449, 1974

    Cited by (1)

  • <no title>

    DRESSLER S.

    Proc. Int. Conf. on Ion Nitriding, ASM International 43, 1986

    Cited by (1)

  • <no title>

    UMA M.

    Surf. Coat. Technol. 107, 55, 1998

    Cited by (1)

  • <no title>

    KANNAPPAN A.

    Met. Form. 36, 335, 1969

    Cited by (1)

  • <no title>

    KANNAPPAN A.

    Met. Form. 37, 6, 1970

    Cited by (1)

  • <no title>

    CHILD H. C.

    Proc. 2nd Int. Cong. on Heat Treatment of Materials, 1st National Cong. on Metallurgical Coatings 89, 1982

    Cited by (1)

  • <no title>

    RIE K. -T.

    Werkst. Korros 33, 647, 1982

    Cited by (1)

  • <no title>

    FRANK E.

    Hart-Tech. Mitt. 38, 110, 1983

    Cited by (1)

  • <no title>

    RIE K. -T.

    Proc. of Int. Conf. Plasma Surface Engineering 1, 201, 1988

    Cited by (1)

  • <no title>

    TOSIC M. M.

    Mater. Sci. Eng. A 140, 469, 1991

    Cited by (1)

  • <no title>

    SHARMA R.

    Wear 74, 1, 1982

    DOI  Cited by (1)

  • <no title>

    FISHER A.

    Wear 152, 151, 1992

    DOI  Cited by (1)

  • <no title>

    NAVINSEK B.

    Surf. Coat. Technol. 142-144, 1148, 2001

    DOI  Cited by (1)

Codes

Page Top