Aluminum Bronze Castings

I'm not a specialist in bronze or foundry, but... Some years ago, I have watched a serious discussion between our material certification engineer and a supplier that had just sent a truck loaded with Al-Ni-Br and Be-Cu bars. The problem was that the material analysis matched the chemical spec and alloy correctly, but the supplier forgot to observe the referred standard regarding porosity. As most of the known world uses the materials for machine bearings manufacture, where the porosity is even benefic in allowing lubricant to flow under pressure or even retain lubricant when coasted to a rest, he thought it was alright. But the material in question was about to be used to manufacture landing gear bushings, and porosity in this application would be fatal for the product endurance. Why did I mention it? Back to your question, this may be the reason for so many and long cast and TIG repair. As he is making valve bodies, you may expect leakages or even short term cracks if porosity and such discontinuities are present, specially under high pressure. This kind of stuff is usually achieved by vacuum or low pressure casting, vacuum remelting, controlled atmosphere, well developed foundry processes. I could also guess (guessing of course, don't know the details about your product, process or project), it would be significantly more expensive than cast and TIG weld... Its also about money of course. The difference in the delivery time for a process with this level of development will pay for itself?

It is castable. Use thin coating of cleanly reducibale polymer which keeps alloy propertries of radiographic needs. If you need further information you can always Google this and will find or may contact me on Masyood@gmail.com since it is not worth of others time with fine details.

Masyood

Hi,

I know that many of the Al-bronzes are cast in tube-like shapes - thus by centrifugal forces any gas is at the inside and removed by machining. (For ships propeller-bearings and similar applications.

So if you want to make these castings good: try to locate the gas sources, very likely bad Al at melting without sufficient outgassing and without prior low temperature drying.

Get new Al ingots for melting and heat the Cu to 300°C if no inert gas or higher with inert-gas covering and add both constituents only if hot.

If not possible you may try a procedure of first vacuum melting and then pressure casting.

But any tiny amount of water (absorbed on the outside and in the Al-oxide layer) will react with the molten Al to give hydrogen and this will cause the problems.

RHABE

Thanks RHABE..Your suggestions are well taken also the efforts of others who responded kindly..

I am replying to Forum thread by Bala Pullat:

I am Ganesan, CEO of Maruthi Castproducts, Chennai. India I am a metallurgical engineer from IISc, Bangalore. I do not know where U are sourcing from.

I wonder why ASTM B 148 Al. Bronze alloys can not be poured without porosity or foundry defects. At Maruthi Castproducts, I pour sand castings of Valve Body, Bonnet, Wedge, Valve seat, Rings, BFV disc in UNS C 95500,95800, 95200 and also in NAB to NES 747 Part II. I am supplying to three customers in Chennai alone. I also manufacture cast and forged blanks in C 63000 alloy.

Valve body castings made by us pass thru R'Graphy level I and II as demaded by customers. We pour castings under witness by DGQA, IRS and ABSIV. U can refer to anyone of these leading inspection agencies. max piece wt.200 kg.

What is significant is correct usage of raw materials and processing.

U can reach me at maruthicastproducts@rediffmail. com or mobile number

9003019822 Regards

S.N. Ganesan