Any info on 4140 steel

Discussion in 'Knife Maker Shop Talk' started by bigbob68, Oct 20, 2009.

  1. bigbob68

    bigbob68 Well-Known Member

    RMJ Tactical uses it for his "Tactical Tomahawks" and was curious as to its performance. Thanks as always. I kinda like these tactical tomahawks.
  2. Nathan The Machinist

    Nathan The Machinist Well-Known Member

    4140 can not be hardened very hard. I was considering using it for some high performance hammers, but further research led me to use 4150 which is very happy in the low HRC 50's.

    4140 is a medium low carbon alloy steel used for high toughness applications such as shafts like axles and other demanding applications requiring high impact toughness and ductility (at the expense of high strength). 4150 is a similar alloy that is used in higher hardness applications and might be a better alloy for something intended to hold any kind of edge or resist deformation.

    They are both machinable, 4140 being easier. They are both reasonably priced, 4140 being cheaper. They are brine or fast oil quenched - most recommendations are for fast oil.

    There are HT requirements necessary to set the micro structure before your final HT for these alloys in their as delivered condition. If I recall correctly it is:
    soak at 1600, cool
    soak at 1550, cool
    soak at 1500, cool
    austenitize at 1525, quench in fast oil
    temper 300-1000
    Last edited: Nov 17, 2009
  3. bigbob68

    bigbob68 Well-Known Member

    Thank you for such good info. I guess that i will stick to a good field axe of some sort. maybe a Wetterling?
    Last edited: Oct 20, 2009

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