Ideal Steel Alloy for Shovel-type Tool Fabrication

I have been using a custom proprietary hand tool for work that is most similar to a shovel in that it experiences quite a bit of abrasion,it meets up with some steel objects now and then and also does some prying and experiences occasional impact,though not on any level of a breaker or jackhammer.The tool is now made of 6061 aluminum,but is ready to receive a re-design in which the business end will have a steel wear plate and chisel-style end.

My steel needs to be formable in a brake,easily weldable (TIG,is fine),take a good impact,and hold up to a good amount of abrasion.Post fabrication hardening suggestions needed as well.

Weight is a huge consideration,as this is a hand tool,ergonomics are everything and ounces matter.My instincts tell me that the wear plate area of the tool would be fine with .075 or .090 plate thickness and the chisel-like end,about .190.The outer perimeter of this plate will be bent over about an inch to give it some structural integrity,allowing other parts of the tool to be lightened or eliminated altogether.

The tool worked fine made completely out of 6061,but would need a lot of attention as far as repair and fish-plating worn out surfaces,just to give you an idea that it works hard,but is not under what I would consider to be severe duty.We are talking about 100 square inches here,and if I fabricate one,I might as well make three.Tool is used outdoors,gets wet at times and is not pampered,a stainless would also be considered.

Suggestions appreciated.

A picture would be nice.

I will suggest hardox 400-500 as formable and weldable.

My first thought is Hardox or similar. Easy to weld, made for abrasion resistance.

Stainless is a whole different game - to get any kind of abrasion resistance, you're looking at either martensitic or precipitation hardening stainless alloys that have enough carbon to form hard carbides in the matrix. 440A/B/C or 17-4 come to mind. 440 is probably going to be easier to weld, definitely easier to heat treat - it's a common knife steel. Another thought is a nitrogen steel, like Z-Finit. Forms nitride instead of carbides, truly a stainless material. Not sure about welding that.

Big design consideration is going to be flexing (elastic deformation) under load - PL/AE on aluminium (any grade), is a lot better than steel. I'd be sitting behind a computer doing lots of FEA to see about that problem.

Without seeing the tool, if 6061 is doing to job, I'd suggest a thin wear plate attached via rivets, screws, or adhesive to the preexisting structure. Save yourself a lot of hassle in the engineering department.

Sorry guys,probably won't be providing a photo,nothing top secret,but when certain folks try to take photos of it,I ask them not to.It is something that guys with 40 years on a construction site will say "hey, that's cool" and a little kid will see it in action and say,"hey that's cool!" Kind of easy to understand when you see it in action.It's just a piece in the puzzle of a more complex job that we regularly do.A shovel is the closest common thing I can think of under the same type of stresses and wear.

Apt,I made the first prototype 20 years ago,and it was a home run straight away.Just looking to refine the concept a bit,lighten it a bit,and repair it less.Your "thin wear plate on a pre-existing structure" is a good description of what is happening,although I am fabricating from scratch.This is about a 50 man-hour project.85% of this tool will still be 6061.Engineering wise,I am not re-inventing it,but I know it's weak links,and believe I know where it can shed some weight without effecting it.Stainless is a nice thought only because to keep the weight down,I want to use the thinnest material I can get away with,and I don't have to worry about corrosion over time making things thinner yet.

This is the challenge with a hand tool,vs. a dump truck,"the feel" trumps any ideas of overkill.

Oh,and fasteners are a challenge,they need to be out of "the line of fire",and require some design thought,one reason the material needs to be reliable for welding.

In light of that info - the most informed decision could be made if you had some data regarding material wear due to abrasion vs material wear due to corrosion. That'll tell you if using stainless will maximize tool life.

Most stainless (ruling out the super high end particle metallurgy stuff you wouldn't really want to weld) is going to have lower abrasion resistance than a regular high carbon steel. All gets down to carbide volume - Stainless need 16-18% by weight chromium to form the protective passivating layer. That's material that's not going into the formation of wear resistant carbides.

Without knowing more specifics, intelligent commenting is limited but I do have lots of experience from being a shovel operator in my much younger days.

You seem to already know this but I will say it anyway. Weight and balance matters, a lot. Most users will tolerate a hand tool that wears faster than desired or is a little fragile. Those are forgivable characteristics. Increase the mass or decrease the tool balance and the user will stop using it cold.

Material characteristic No. 2 is one that is often overlooked in a hand shovel by most people. That characteristic is the ability for the dirt surface to scour. That is for dirt to slide across the surface without sticking. This characteristic is what determines the amount of force needed to move the tool through the dirt after penetration and upset is achieved.

Most stainless alloys will rate poorly in this but heat treated steel and aluminum do this very well. Surface finish matters a lot.

Final suggestion is to consider alternatives to the chisel point if appropriate.
Taking a lesson in ground engagement from earth moving equipment, chisel point edges are usually avoided as they wear rapidly and require excessive force for good penetration. What works best are sharp points that act as teeth. They wear longer, require greatly reduced force and reduce total mass.

Maybe you're overthinking this. If your current tool is made of aluminum and it works OK then I'd be inclined to think that
"any" steel should work. I'm thinking that even mild steel would be a big improvement...

google Cromweld, its nearly stainless and a hell of a lot tuffer than typical steels, its very tough and springy. its designed for use as chute lining in sand washing plants, its smooth surface is more than up to resisting abrasive wear, its very springy but it also does not readily corrode, its a lie to call it corrosion resistant like most stainless, is but its not all that far behind 304 in reality. the surface will discolour, but you won't really get any rust form. Does not need any heat treatment either. Comes in the thickness’s your looking for too unlike hardox - most of the common wear plates. Would make a truly awesome spade and would not need any backing up - reinforcing to be a spade at typical spade thickness’s either.

LKeithR said:

Maybe you're overthinking this. If your current tool is made of aluminum and it works OK then I'd be inclined to think that
"any" steel should work. I'm thinking that even mild steel would be a big improvement...

Click to expand...

This could be the truth.I put the question up because looking into the material possibilities and what I need as far as weldability,formability and wear resistance,in a relatively thin sheet,was driving me a little nuts.

Thing is,if I make it right,it may not need my attention again for 10 years or more.This is a tool that is used more like weekly rather than daily,but gets thrown in the truck "just in case" pretty often.

Ziggy,this is not really a digging tool,but receives similar stresses.I like your ideas of point vs.chisel,and your reasons are why a chisel actually is more suited for what I do with this tool.

You can also talk to your local heat treater. They have the experience from jobs already and would be able to guide you through a wear and hard steel but probably no help in the welding side of it.

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