CAST A BAR AND THEN FORGE IT METALLURIGAL QUERY? 8

[skengg]

Hello to all, i have one query which generated due while we executing one order, we need to make a spindle say 15 mm finished dia. and 150 length of aluminium bronze grade, i want to ask if we first cast the Raw bar and then forge it in forging press. would they able to match up the metallurgical properties (especially strength requirement) as comapred to Bought out rolled Bar stock properties?

 

[EdStainless]

If you start large enough, get the chemistry right, the heat treatments right, control the temps at the hot forge steps, put enough cold forge in on the final couple of passes, and leave enough stock for machining cleanup you will get very close.
Uniformity will likely be your biggest issue.
After all that is what they are doing. Casting, hot (or warm) forge, HT cold roll to final size, finish anneal.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[blacksmith37]

The ratio of aluminum to iron is important in these grades in addition to the quantity. I recommend getting an experience foundry to make castings. Also , the cast compositions may not forge well.

 

[SwinnyGG]

Every forged bar was first 'cast' in some fashion - you can't forge a liquid.

The only difference may be immediate hot 'forging' of a continuous extrusion vs. reheat hot forging of an as-cast bar.

If you're trying to save money, I'd bet that you won't. Producers of cold-rolled high strength bars are able to take advantage of huge economies of scale that are difficult to duplicate from a cost standpoint when you're doing things at much lower rates.

 

[MagBen]

This is a too general question. cast, cast + forge, cast + forge + cold rolled, buy stock + machined, could all work depending on strength req's. just a balance between cost/strength/availability. However, often cold rolled products give you benefits of higher strength, more uniformity, and consistence, but of course most costly.

 

[skengg]

thanks to all for providing information.
actually order lot is very small and aluminium bronze rod pretty expensive from market that's why we were looking for options as we have inhouse foundry and press shop.

 

[WKTaylor]

SK...

CAUTION... about 'make-it-yourself' wrought product. Most likely Your customer asked for their part to be 'made-from' a specific aluminum-bronze spec bar.

The OEMs for this material have the process 'nailed'... YOU will NOT. The grain structure, orientation, porosity, mechanical allowables, toughness, heat-treat, etc... will be a crap shoot.

ALTHOUGH IT IS TEMPTING to make Your own... DON'T DO IT... get the right material with certification documents from a reliable source and make a reliable part.

No-Sh*t War Story. I was at a welding conference ~15 years ago. A welding scientist was investigating a novel welding process for titanium 6Al-4V plate. He made his presentation and I was caught off guard by the weld-joint tensile and bend 'numbers'. Being an engineer [NOT SCIENTIST] I wanted to know what material specification the plate was made/procured-to for his testing, IE: ASTM, AMS, etc. His reply was shocking... to save big-$$ buying a certified 'as-rolled' Ti-6Al-4V plate... he used a donated [free] short/fat titanium 6Al-4V bar.

Huhhh? Oh kaaaay?? HOW???

He had 'the lab' heat the bar in their research air oven... then the lab crushed it down flat under a massive hydraulic press to 'make the plate'... then they annealed it. Then he machined the specimens and welded them and tested the welds.

Huuhhhhh OOOOoooH H***LLLL NOOOooooo... I argued back that his lab had made a non-specification 'flat forging that looked like a plate'... with none of the surface features, grain, metallurgy or required raw-material testing to validate it to any 'plate standard' [properties]. In other words he had tested his novel weld-process on a unique piece of material... forged, not rolled, plate... that would-not... never-could-be... reproduced by any reputable wrought processor.

This really, REALLY bothered me DEEPLY as an engineer who relies on authoritative material certifications... hence predictable mechanical and physical [etc] allowables for the materials I specify to make airworthy parts.

Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

 

[mrfailure]

SK, pay close attention to Will's story. In the days when I was approving material substitutions, I would have rejected such a request out of hand because the customer is specifying wrought material made from bar stock and you would not be providing that product form. If I could turn a casting into a forged bar with no issues, then I would be able to achieve the ultimate metallurgists dream of turning iron into gold!

 

[skengg]

WKTaylor thanks for providing information as well as your experience,
though we also decided to make spindles from bought out bar stock, its just one of our member from company suggested this idea, intially i also agreed that this is not a good practice.
yes mrfailure,i got the point and i just posted the question to get insight details of these kind of situations. thanks all to giving me your views.

 

[skengg]

by thr way, i have one general query which arises as i was thinking about this.
how we can generally inspect or identify that, is the bar is made from rolled or by casting and forging as i stated above?
like without using any special testing procedure, can visually or just by simple technique we can identify?

 

[SwinnyGG]

There's no clean way to identify that a particular piece of material is of a certain composition or has been processed a certain way without any testing - this is why very robust material certification and tracking processes are important.

 

[WKTaylor]

Sk...

Highest assurance is to buy raw material per a high qality spec from a reputable metals supplier... and ensure the material is appropriately mill-marked/ID and is supplied with material certifications as to all facets from a qualified laboratory.

SAE AS6174 Counterfeit Materiel; Assuring Acquisition of Authentic and Conforming Materiel

NOTE1. For some materials where a minor amount of porosity is allowed, we specify thru ultrasonic NDI to validate internal porosity and location, plate, bars, shapes & forgings, thus...

NAS824 Inspection, Ultrasonic, Wrought Metal

AMS-STD-2154 [MIL-STD-2154] Inspection, Ultrasonic, Wrought Metals, Process for

ASTM E2375 Standard Practice for Ultrasonic Testing of Wrought Products

Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

 

[skengg]

Ok swinnyGG
thnanks WKTaylor for giving extra information regrading it.