Post Weld Heat Treat - Thermite Weld

I am looking for the PWHT (Post Weld Heat Treat) temperature for tangent (straight) standard rail 300 HB (Brinell Hardness).    Does anybody know what the temperature and duration is?

5 Replies

  • In refernce to Thermit welding;  Post-heating methods are used for certain circumstances.  Do you mean Pre-heat procedures?

    If your  Post- heating or Pre-heating several things need to be identifed prior to doing anything.  Railsize, BH, HH or STnd, etc etc.

    Most importanly!  Which Thermit weld are you installing?  There are several companies out there that require diffrent procedures.

    May I recomend that you purchase training from the Thermit Co. prior to insatlling any welds.  Therfore you're properly trained and you avoid any liability issues.

    Remember!  SAFETY is the ultimate goal!

  • In reply to Thermit101:

    This is for 115 lb rail, standard 300HB hardness.  The thermite weld is for a signal cable being installed at the Web of the rail.

    Actually, you bring up a good point.  I am interested in both pre-heat and post-heat procedures.  I understand a pre-heat is beneficial but how much.

    A post heat treatment of the rail for existing thermite welds I understand, is impractical in that you will need +1400°F.  Is this true?

    We have discovered brittle martensite at the point of the thermite weld;  and this was after following the mfg instructions exactly. 

    Thanks for your input!

  • In reply to MechEng:

    MechEng

    This is for 115 lb rail, standard 300HB hardness.  The thermite weld is for a signal cable being installed at the Web of the rail.

     

     

    There has been great discussion of late about track wire installation techniques and martensite.  I happen to be a member of an AREMA committee whose members are working to address this very issue.  Several field studies have been conducted or are ongoing about same.  Feel free to look me up off-list.  I'll be happy to put you in touch with some of the folks involved.

  • In reply to mjengels:

    MechEng would do well to access the TCRP website at www.tcrponline.com and download TCRP Report 71 Vol 3 "Exothermic Welding of Heavy Electrical Cables to Rail - Applicability of AREMA Track Recommended Practices to Transt Agencies".  Many agencies/owners have ceased using thermit welded cable/wire connections because of rail breaks, and are using mechanical connections, instead.

  • In reply to William Moorhead:

    Excellent, thanks for the responses.

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