316 or 304

Discussion in 'Materials' started by MKP, Sep 13, 2008.

  1. MKP
    Joined: Jul 2008
    Posts: 35
    Likes: 1, Points: 0, Legacy Rep: 26
    Location: Benicia, CA

    MKP Junior Member

    Guys,

    I am having some struts built for my new shafts. I need some help researching the best materials to use. My shafts are 2"OD and the drop from the hull to the center of the shafts is about 14". The yard wants to use 1" flat-bar stock and a .5" wall thickness tube for the bearing housing. This seems over-kill to me. They also don't have a preference between 316 or 304. This scares me a little as I am under the understanding that 304 was a no-no under the waterline.

    do I need to spend the extra money on 316?

    Should I be looking to have bronze struts cast and avoid any SS? Does anyone have experience ordering custom struts from Buck Algonquin or Marine Hardware?

    Thanks in advance,

    Mike
     
  2. Çemberci
    Joined: Apr 2007
    Posts: 127
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    Location: Istanbul/Turkey

    Çemberci Senior Member

    304/316

    Hello Terminated Stainless Man,

    Differences between 304 to 316

    Oktay Çemberci
    Code:
    304  	UNS:S 30400
     
    MECHANICAL PROPERTIES
    Tensile Strength 	87 000 psi
    Yield Strength 	39 000 psi
    Elongation 	% 56
    Reduction of Area 	% 70
    Brinell Hardness 	135
    Impact Strength 	85 ft Lb
    Endurance Limits 	35 000 psi
     
    Chemical Composition
    Ni 	9.25
    C 	0.08 Max
    Mn 	2.00 Max
    P 	0.045 Max
    Cr 	19.00
    Si 	1.00 Max
    S 	0.030 Max
     
    Physical Properties
    Density 	0:290 Lb/in3
    Electrical Res 	433 ohm-CMF
    Service Temp 	870 C
    Coef of Exp 0-200 F 	9.6 * 10 -6
     
    
    Code:
     
    316 	UNS : S 31600
     
    MECHANICAL PROPERTIES
    Tensile Strength 	84 000 psi
    Yield Strength 	40 000 psi
    Elongation 	% 52
    Reduction of Area 	------
    Brinell Hardness 	128
    Impact Strength 	--------
    Endurance Limits 	39 000 psi
     
    Chemical Composition
    Ni 	12.00
    C 	0.08 Max
    Mn 	2.00 Max
    P 	0.045 Max
    Cr 	17.00
    Si 	1.00 Max
    S 	0.030 Max
    Mo 	2.50
     
    Physical Properties
    Density 	0.288 Lb/in3
    Electrical Res 	444 ohm-CMF
    Service Temp 	870 C
    Coef of Exp 0-200 F 	8.9 * 10 –6
     
    Source from Nikel Developmant Institute-NiDI
    
    
     
  3. MKP
    Joined: Jul 2008
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    Location: Benicia, CA

    MKP Junior Member

    so which is best under water??????
     
  4. Çemberci
    Joined: Apr 2007
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    Location: Istanbul/Turkey

    Çemberci Senior Member

    316

    Underwater material is both 316 or 316 L
    oktay Çemberci
     
  5. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    316 L prefered, if not then 316.
     
  6. MKP
    Joined: Jul 2008
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    Location: Benicia, CA

    MKP Junior Member

    no 304???
     
  7. RHough
    Joined: Nov 2005
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    Location: BC Summers / Nayarit Winters

    RHough Retro Dude

    SS is not the first choice below the waterline, if you must, use 316 and put up with the 15% loss in strength compared to 302/304.

    I'd price the bronze before I decided.
     

  8. Wynand N
    Joined: Oct 2004
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    Location: South Africa

    Wynand N Retired Steelboatbuilder

    316 L...
     
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