Old Material callout

[Boomerfood]

Hi guys,

Working on an old (same age as me) hydro plant and need to know what material I'm seeing. The print says Steel 125/105 16/50. I assume the 125 is ultimate strength of 125,000 psi and the 105 is yield strength of 105000 psi. The 16 would be percent yield but what the heck is the 50?????

Thanks,
Jeff

 

[Dougt115]

My old book has 16/50 as elongation percentage and percent reduction in area.

 

[Boomerfood]

Thanks!!

 

[Boomerfood]

Any suggestions on material that meets these spec's? A search on matweb.com brought up some SS and a lot of beryllium copper. Thought I was on Galaxy Quest.

 

[metengr]

Boomerfood;
For proper material selection, you need to know the product form (including size), service and environmental conditions to select a comparable grade of material.

 

[redpicker]

You are pretty much looking at a Q&T low-alloy steel to achieve those properties. This will mean product form (pipe, bar, plate, etc...) & section size will be important. You need a bit more information to be able to make a material choice.

rp

 

[arunmrao]

Can you tell more about the part that you are mentioning. Is it the turbine, rotor shaft? Also, are they cast, forged ,machined etc will be helpful in getting better responses.

 

[Boomerfood]

It is a tapered pin that holds the deflector linkage together on a Pelton unit. As such, it gets a lot of water on it. Well, just the end that is exposed. We are replacing the shafts and have to drill new holes for new taper pins to put it back together.

 

[metengr]

What is the maximum diameter of the tapered pin?

 

[Boomerfood]

1.241 +/- .002 5.75 long Taper .25 per 12" standard taper but bigger than ones I can find for sale.

 

[tbuelna]

As redpicker noted, there are some low alloy steels that will provide close to the combination of properties you noted in a Q&T condition. But it sounds like you really want a corrosion resistant steel for this taper pin. I looked at some of the common cres alloys, but I did not see one that met all of your requirements for UTS/YTS/EL/RA.

 

[metengr]

How long did the previous tapered pin last? As an option, if you have a sample of a tapered pin that was removed even in pieces, send it to a met lab and have it typed for material composition.

 

[arunmrao]

Corrosion is less of a problem, but erosion is a major concern. For, a lot of sand and gravel flow , which is a cause of major concern in hydroturbines.

 

[EdStainless]

Q&T alloy steel should hold up well (it did last time).
If you want more corrosion resistance (and spectacular erosion resistance) you should look at duplex stainless steels. Alloys like LDX2101 are available as cold finished bar. They would have plenty of strength and great corrosion resistance.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[JOHN083]

AS I KNOW ASTM A193 B7 MATERIAL WILL CONFORM THIS MENTIONED MECHANICAL PROPERTIES WITH MAX HARDNESS OF 35HRC IN Q& T CONDITION

 

[Duwe6]

btw -- ALL CAPS IS RUDE

 

[Dougt115]

All caps is for yelling, emphasis, or acronyms. Otherwise...rude.