Handle material 4041 al vs. 6061 steel, corrosion in atmosphere.

[airhog]

Hello, I am currently looking into changing a lifting handle from 6061 aluminum, to a steel handle.

The lift handle will be used in a indoor environment.

I am wondering if I should just go right to 304SS instead of messing with 4041 and using some type of coating, nickel plating. Costs are a concern.

Currently the 6061 al used is not anodized and holds up great.

Any assistance that could point me in the proper direction would be appreciated.

 

[airhog]

ETA:

Just to clarify, I meant 4140 steel and 6061 aluminum.

Thanks

 

[jtseng123]

why change if the existing works fine ?

 

[1gibson]

I've heard that 6061 holds up great.

If you want it cheaper, make it hollow?

 

[airhog]

Hello Jtseng123,

The reason for the material change is because the handle has been modified with a hook to hang a plate assembly.

Because of the weight and the insert used, purchasing the Al handle then modifying the Al handle is expensive.

I plan on pricing out some plating options to see the cost savings vs. stainless steel, especially in the quantity used.

However, I wanted to get some opinions on potential steel alloys that have similar corrosion characteristics to 6061 Aluminum.

 

[airhog]

This handle holds a significant amount of weight, therefore making it hollow is not an option. Especially with the recent modifications.

It will have to be:

Steel
Steel with corrosion inhibitor
Stainless Steel

 

[1gibson]

Sorry, 8/31 was a Friday and my crystal ball tends to act up on Fridays.

Turns out Mondays it is not that great either, why are you changing material? Here is what you've presented so far:

1) Buy finished 6061 handle and modify for hook - too expensive
2) Buy raw material (that is different than 6061???) and machine complete.

Still, you have a material change for no apparent reason.

How about option 3, buy raw 6061 and machine complete? Am I still missing something? Do you need a stronger material? Do you need better fatigue characteristics for the hook?

*shakes crystal ball*

Damn, still nothing.

 

[airhog]

Hello Gibson,

My crystal ball tends to work intermittently as well.

The handle does need to be stronger than the current aluminum one, thus the material change.

I am also trying to standardize components so the custom hook (used else where) can still be used and not modified in any way. I thought such details were outside the scope of the materials question.

I was trying to find a steel that would not develop surface rust, for esthetics reasons when used indoors. Now the tricky part, without going to SS, nickel, painted coatings etc. I am willing to accept such an alloy does not exist, just wanted to check the wealth of information provided here.

Thanks

 

[coolbreeze]

6061 is one of the lower strength aluminum alloys, about 20ksi. 2024 has a tensile strength of about 60ksi and has good corrosion resistance. You can be sure that it will not be as cheap as 6061 though. Mil-HDBK-5 is one of the best resources available on aluminum alloy properties and it is free for download

https://assist.dla.mil/

The handbook also includes steel, but focuses on Al.

 

[redpicker]

If you are still wanting to use steel, have you considered an oxide coating, such as bluing used on gun barrels? Would paint work? How about galvanized?

What is the consequence of surface rusting? A minor appearance issue or does it cause the entire assembly to fail?

Steel componnets are used all the time in indoor environments with no problems without rusting being an issue. Coat hangers receive a lacquer coating and do just fine.

But, if you want an sepcific steel grade that will rust less than others, without going to a stainless steel, you aren't going to find much.

If you do go with stainless, consider a ferritic stainless, 410 or something similar, instead of the 304; it will be less costly and unless corrosion is a serious problem, it will do just fine.

rp

 

[mrfailure]

First, I think it is important to understand what the design requirements are for the modified handle. In particular, what are your minimum required tensile and yield strengths required for the new design.

Second, after looking at design requirements you should question whether you need to change the material system at all. I only do such a thing as a last resort as changes in base characteristecs can create new issues beyond simple strength (such as, as pointed out, finish and corrosion resistance). I would first look at 6061 again for the new design but consider a different temper. You did not mention the temper currently used and this makes a huge difference in mechanical properties. For 6061, O-temper has 18 ksi UTS/8 ksi YS; T4- 35 ksi UTS/21 ksi YS; T6- 45 ksi UTS/40 YS. (These are typical values which I took out of ASM Handbook). You may simply need to specify a different temper of this alloy for your needs, which would be the preferable to changing material.

Aaron Tanzer

http://www.lehightesting.com