Peter
Check this out , i hope it could help
6XXX Series Alloys – (heat treatable – with ultimate tensile strength of 18 to 58 ksi) These are the aluminum / magnesium - silicon alloys (magnesium and silicon additions of around 1.0%) and are found widely throughout the welding fabrication industry, used predominantly in the form of extrusions, and incorporated in many structural components. The addition of magnesium and silicon to aluminum produces a compound of magnesium-silicide, which provides this material its ability to become solution heat treated for improved strength. These alloys are naturally solidification crack sensitive, and for this reason, they should not be arc welded autogenously (without filler material). The addition of adequate amounts of filler material during the arc welding process is essential in order to provide dilution of the base material, thereby preventing the hot cracking problem. They are welded with both 4xxx and 5xxx filler materials, dependent on the application and service requirements.
As per ASME IX QW/QB 422
Smls. pipe & tube
Spec.No. B 345
UNS A96063
Alloy 6063
regards
They could also be talking about a carbon steel alloy that also includes silicon and manganese for high temperature applications. A typical example would be ASTM A106 steel pipe. It is close to the composition of ASTM A53, but with increased silicon and manganese to allow for a reduction in carbon content to minimize graphitization when subjected to "high" temperatures for extended periods of time.
Both silicon and manganese in small amounts are used as deoxidizers in steel, but in increased amounts they act as alloying constituents thereby allowing the amount of carbon required for equivalent strength to be reduced.
ASTM A53 carbon steel pipe, commonly called black iron pipe, is fine at lower temperatures, but at higher temperatures the carbon can form graphite platelets that will cause a loss of strength and embrittlement. That's when A106 pipe is used in place of A53. The lower carbon content of A106 means there is less likelyhood of graphitization while the manganese and silicon maintain the required strength.
The weldability of A106 is on par with the A53, i.e., both can be welded with the same SMAW, GMAW, or FCAW filler metals depending on the application, position, and equipment availability. Both A53 Grades A and B and A106 Gr A, B, C are P-1 base metals per ASME and both A53 Gr B and A106 Gr B are Group 1 as per AWS D1.1. The grade indicates the tensile strength of the pipe, so, the fitter should not substitute grade A for either grade B or C since the strength increases as the grade letter increases.
Best regards - Al
This is a great example of how confusing it can get when all the necessary information isn't provided to either the welder or by an inquiry!
Similar problems crop up when questions are asked about P21 (and P22). I had a call once where the caller wanted to know what filler metal to use with P21. I thought he was asking about P-21 with regards to aluminum alloys not Cr-Mo steels! You should have heard his laughter when I suggested an aluminum filler metal! :0
The same with 316. 316 is an alloy designation for austenitic stainless steel but it can also be used to designation for a cast aluminum alloy!
Best regards - Al
Al,
Please correct me if i'm wrong, Peter is asking for the Silicon-Magnesium piping as the alloying element and A106 Gr. B the nominal composition as per ASME IX is C-Mn-Si.
Best Regards,
Yes, but often times it is simply referred to (incorrectly by the way) and silicon-manganese steel.
That's the point I was trying to make. Are we talking about aluminum or steel alloys. Partial information can lead us in the wrong direction rather quickly.
From the "tone" of the question it seemed the person making the inquiry didn't know for sure whether it was aluminum pipe being welded or something else.
The 6061 variety for aluminum alloys, very popular for structural applications, are composed of magnesium, silicon, and perhaps some copper, but no manganese. The 3XXX series is alloyed with manganese and magnesium, the 5XXX series is alloyed with magnesium and manganese, but neither is alloyed with silicon unless it is in rather small quantities. However, the 4XXX series of filler metals are alloyed with silicon and magnesium, but typically not manganese and silicon.
The possibilities are endless when we don't have "the rest of the story."
Best regards - Al
Silly me, I just went back and reread the inquiry and you are absolutly right. It does mention silicon-magnesium!
Give me a minute or two to pull the rest of the feathers out of my mouth along with my shoe!
Best regards - Al
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