Steel Hydrogen Embrittlement

[TRRMan]

I need some clarity on when Hydrogen Embrittlement should be a concern. ASTM B633 states that "All electroplated steel parts having a tensile strength greater than 1000 MPa (31 HRc).... shall be baked to reduce the risk of hydrogen embrittlement." If I have a 1045 sheet metal plate which tensile strength is below 1000 MPa and then heat treat it to HRc 38-42 does that then fall within the required range for baking out because the MPa value is now greater? My machinerys handbook is just a vague only mentioning high strength steels (above 1700 MPa) which it states shall not be plated and parts over 1200 MPa which should be baked out for 3 hours.

Thanks

Todd

 

[israelkk]

The answer is yes the condition of the steel when is going into the plating bath is what determine if it needs baking or not. Since your plate is 38-42 RC it needs to be baked as soon as the plating is finished (within max 4 hours) the sooner is better.

 

[TVP]

If the part is electroplated after heat treating to 38-42 HRC, then yes, it should be baked for hydrogen embrittlement relief. There are many steel parts that are heat treated to very high strength/hardness that are not exposed to hydrogen and therefore are never baked (think gears, bearings, etc. that are always in an oil environment).

 

[TRRMan]

Thanks for the information.

What is the typical bakeout specification, 3 HRs at 375F?

 

[israelkk]

TRRMan

The information for baking time and temperature is included in ASTM B633. If you are required to zinc electroplate per ASTM B633 you should carefully read and study the ASTM B633. From my experience one of the reasons for failures and conflicts is that many engineers take shortcuts and do not bother to learn and understand the requirements of processes they put on the drawing. They rely on partial information from friends and other professional who never read the spec themselves.

 

[TRRMan]

israelkk

I see the additional ASTM spec that it is calling for that defines the post plating process information. I know what you are talking about, I have a big mess to clean up from years of sloppy engineering pratices so I am trying to get the best information that I can and also educate myself. Thanks

 

[mfgenggear]

an other very good document is AMS2759/9 Hydrogen Embrittlement Relief(baking of steel parts.
It also explains it all.
It gives diffrent temps & time required,
depending on the process used & types of steel.

It's very good to seek recommendations.
Israelkk is right read all you can stand, then ask more questions.

 

[unclesyd]

When there is a question or any doubt do it.