Casting Repair

[TCrush]

I have a boom (about 6 foot long) that is made IAW ASTM-A27,A148 Class 150-125 chemical composition is equivalent to 4130 Except Si is .64%, and is furnish in an “as cast” condition.

Due to misuse the lower part of the boom is wearing to a point that there is some concern it will not carry the required load. I have been working on a repair procedure, but since I am not familiar with cast repair I’m a little hesitant to recommend something.

What I am considering is removing (by machining) the worn part and manufacturing a new piece to replace it and then weld it in place. This new piece is basically a 3”dia by 6” long cylinder that will be 'fitted' into the end of the boom.

Is there any detailed information available, mainly on the welding design, how much? Or are there any companies that can do this repair?

There is also a track the attaches to the end of the boom that needs to be repaired as well. Same material, a little different repaired needed.

Thanks in advance.

 

[metengr]

The materials that you describe for the boom are indeed repairable by welding. The best advice I can give is to locate a competent welding or metallurgical engineer to evaluate the feasibility for making this type of repair (especially if failure of the boom results in loss of productivity or harm to personnel). A competent welding engineer should have the expertise to generate a weld repair program based on material thickness and the configuration of the boom.

I would start searching for a Metallurgical/Welding laboratory or consultants in your region. Describe the problem to them. They should send a field engineer out to evaluate your situation and provide recommendations. Check all references (including having a PE license) and rates before committing to a consultant.

Once a weld repair program is developed it can be properly executed using a competent mechanical repair organization. The key for this repair organization is to have demonstrated welding capability in the form of qualified welding procedures and welders – especially working with mechanical equipment. The welding consultant should be able to help you in this endeavor.

 

[unclesyd]

I have to agree and disagree with metengr all at the same time. I agree that you need competent guidance and competent repair shop.

Depending on how the boom is used and on what equipment it may fall under one of the OSHA/ANSI guidelines and may have to have a authorized repair station or written permission from the OEM to do the work. A competent shop can guide you on this aspect. Agreeing again if there is any hesitancy on anyone’s part then get engineering help

Check in your area for a complete shop, welding, machining, old, that works on heavy equipment such as backhoes, front-end loaders, and such. A competent shop can repair most equipment by means such as welding and machining, by machining and installing a steel bushing. Your material is quite common on hydraulic cylinder pivot ends.

 

[TCrush]

Thanks for the feedback I have pretty much decided to let the ‘experts’ deal with it, but knowing what needs to be done and how goes a long way in making sure we get a reliable repair. And since the equipment will be handling bombs I do not want a failure.

Thanks again....

 

[Metalguy]

Are you sure the steel is "as-cast"? If so, it has a HUGE grain size and I sure wouldn't want to be anywhere near it, esp. if the temp. is anything lower than ~250 F. The common practice is to at least normalize it after casting.

 

[unclesyd]

If this is piece of equipment is for or used by the military or handling parts for the military on a base you will need to check and see what the military requirements for repair are.

You might have to jump through hoops.

 

[TCrush]

"As cast" is what’s on the original drawing. My gut told me that did not sound right, which is why I'm trying to educate myself in this area.
From what I have been reading it should have been normalized, and I really do not have much faith in the OEM that it was. The operating temps are what you would expect as normal ambient temps, the worse temps being what the Marines are seeing.

I am the “hoops” that are being jumped through…I’m a government Engineer…which is part of the reason I’m trying to get a good understanding on this, so that I can avoid the “hoops.”

 

[unclesyd]

I've always wanted to meet one. Hi!

I don't how the repair set up is in today’s armed forces but at one time there were Naval Air Depots, the one that was at Pensacola was "NADEP Pensacola". This group had several competent metallurgical and material people as well as inspection and repair facilities. They would either do the work in house or write the procedures for an approved shop to do the work offsite. They did work for both the Navy and Marines.
There should be some comparable facilities that you could access for assistance.

When the Pensacola group disbanded we hired the head NDT man and the head of the group formed a world class Forensic, Metallurgical, and Materials Engineering Lab. Guess who his best customer is? The Armed forces.

 

[Metalguy]

ICrush,
The microstructure can be determined fairly easily in the field via plactic-tape replication and exam. in an electron microscope. If it really is as-cast, you might be able to normalize it in a large furnace-esp. after any weld repairs.

 

[TCrush]

The biggest problem we have is lots of retirements and closures forcing us to loose a lot talent. I actually work at a depot as a engineering rep for the Navy's In-Service Engineering for Aviation Support equipment, and I’m the one stuck with writing these things, so that our on site contractor or a better suited offsite facility can "get r done".

 

[GRoberts]

The first thing that jumped out at me as well, is the "as cast", which if true, makes me think you are going to have a miserable time with this casting. If it was normalized or Q&T (quenched and tempered), you will be a lot better off. As far as the weld repair itself, if you are going to attempt it, you might consider using inconel 625 (NiCrMo-3) filler metal, as it is more ductile and only slightly less strong than the base metal. It will also limit the propensity of the part to hydrogen crack due to its austenitic microstructure. Preheat will need to be fairly high (you might be able to get a preheat calculator from Lincoln electric that considers the chemistry of the materal and the thickness as well). A PWHT would be highly recommended as well. If you do not know the heat treat history of the part though, it will be hard to determine the proper temperature.

 

[silouane]

You are not obliged to use an Inconel, but it is an easy way. Also you can do repair with out any PWHT. I imagine you have a high CE. For welding you have to balance HI and pre-heat. In any case you will have a martensitic zone. More over, this kind of material has a high level of Mn that means a low H content. If you have that I advise you to check the TRC diagram of this material.
At the present time I have to do a butt weld with this material on 120mm thick. As a mark for you, I determine that TR800/500 shall be over 7seconds.