Yield Strength and Wear Properties of Steel
Yield Strength and Wear Properties of Steel
(OP)
Could someone offer me some advice on the "wear-ability" of steels of varying grades? (i.e. 80ksi vs. 50ksi vs. mild steel) Is there any correlation between yield strength and "wear-ability"? Thank you.





RE: Yield Strength and Wear Properties of Steel
RE: Yield Strength and Wear Properties of Steel
For each wear mechanism, you could probably find information in reference books on Tribology or by using the internet that would descibe what variable(s) have a direct affect on wear rate of materials.
RE: Yield Strength and Wear Properties of Steel
The wear I'm talking about is of the "abrasion" and "sliding damage" nature. I am considering changing the material for my application from an 80 ksi yield strength to a 50 ksi yield strength. It was brought to my attention that maybe this wasn't a good idea because this part is continuously rubbing against another, even though there is grease in between the two parts to reduce friction. All our experience has been with the 80 ksi yield strength material so far and I was trying to get a feel for some of the concerns that were raised when I made my suggestion.
metengr, forgive my ignorance and thanks for the tip on Tribology. I will look it up.
RE: Yield Strength and Wear Properties of Steel
additional processes to achieve this property:
1.) Apply some type of interface between the concerned parts such a abrasion resistant material applied to the base metal by hardfacing (welding, thermal spraying or cladding).
2.) Heat treatment can help but not as much as the previous method. 1045 is not an abrasion resistant material.
If you decide to go with recommendation no:1 above, make sure the hardfacing material is designed for abrasion and not impact. These are often two different materials, but not always. Also, make sure the hardfacing material applied is of the machinable type. There are hardfacing alloys available in for machinable welds and non-machinable welds.
Good luck and let the forum know how you came out with your modification/repair.
RE: Yield Strength and Wear Properties of Steel
RE: Yield Strength and Wear Properties of Steel
The problem is two-fold: 1) the pick-up interaction between the trailer and the truck, and 2) the slipping and sliding as the coupled vehicle is in operation. Both of the above will try to wear on the interacting surfaces. These days 80ksi yield steel is becoming less available and more expensive, hence the consideration to change to the more abundantly available 50 ksi yield steel.
While I know that the wearing of the surfaces in contact can be minimized by the lubricants present in the joint, I can't count on everyone using their equipment exactly as it was intended. The trucking industry is not so perfect which makes me design with the worst case scenario in mind.
This is my first time on this Web site and I am quite pleased with the speed which with I have received your responses. Thank you all and I hope I can return the favor to some one one day. In addition, I will let the forum know when we finalize this decision.
RE: Yield Strength and Wear Properties of Steel
nick
RE: Yield Strength and Wear Properties of Steel
Having being a heavy equipment welder/mechanic in my younger days, this is a problem as old as the industry itself. The entire 5th wheel (kingpin) assembly gets a lot of beating during service and coupling. This application is subject to abrasion, shear, fatigue, tensile and impact loads. I know, I beat up a few moving tractors and trailers to the work area.
If you can develope a system/method to mitigate this problem, you will probably retire early.
RE: Yield Strength and Wear Properties of Steel
Now the $64,000 question: Is a lower hardness material high enough for this application? I guess that's why we engineers get the big bucks, right?!?
RE: Yield Strength and Wear Properties of Steel
the charts seem to be related to
hardness. It also seems to be of
some advantage to have the materials
not of the same hardness to reduce
the welding phenomenom. Possibly you
could shot peen the interfaces as
well before assembly ie work handening
these surface. I do not think it would
be that expensive to induction harden
or hard coat the interfaces.
RE: Yield Strength and Wear Properties of Steel
We recently had some coal barges that required rub plates to be fabricated to reduce susceptibility to wear damage from impact and abrasion. The following web site is where we had purchased this abrasion resistant plate material. It is made by a Swedish company that provides it in a quenched and tempered condition - hardness with good toughness. It has excellent weldability and formability.
http://www.hardox.com/us/default.asp
RE: Yield Strength and Wear Properties of Steel
RE: Yield Strength and Wear Properties of Steel
http://www.astralloy.com/products/av/astralloy-v.asp
RE: Yield Strength and Wear Properties of Steel
They are currently using a steel w/ a yield of 80ksi. This sounds like an HSLA steel. (IE 980xf for example) If they're having a hard time getting material its cause we all are. The problem is not that their current material is not working well or wearing out quickly. Its that they want to go to the more available and cheaper 50ksi yield grades. (IE 950xf)
I really dont see why they would want to go to a highly alloyed steel from their current material. All they would do is significantly increase cost over the current working material.
If I am way off base here let me know.
[NOMEX suit]
nick
RE: Yield Strength and Wear Properties of Steel
By the way, metengr, we have looked at some of the higher strength Swedish steels for different applications but that again exposes us to international risks that we are barely exposed to now. That's not to say we never will try them. Another issue is volume. We use a whole lot of steel and I'm not sure how much volume consistently they can support.
Our industry is just not that cutting edge. It's a very mature industry with trailers basically considered as commodities--box-on-wheels. Margins in such a mature industry are VERY tight and that is why I think innovation is squelched. Companies just don't see the payoff in taking the risk because the ones that have tried in the past have had their noses chopped off. I haven't had my nose chopped off but I can imagine that it doesn't feel very good!!
RE: Yield Strength and Wear Properties of Steel
The hardness and material of the 5th wheel is something to look at. If cast iron is the mating material, the plate hardness will not matter. The primary concern will be thickness, to thin and it will dent and crack when connecting the trailer. I have seen this plate dented and cracked on some used trailers.
RE: Yield Strength and Wear Properties of Steel
Based on what I know of our experience with thickness of the plate and the 5th wheel being cast iron, it seems as though I don't have an issue here. Would that be a reasonable conclusion?
RE: Yield Strength and Wear Properties of Steel
Higher strength material will spring back in place when deformed with a higher load than a lower strength material. To eliminate the over deformation of the lower strength material it must be thicker.
Cast iron is used in hydraulic cylinders for the head and piston, as well as low speed plain bearings. Cast iron tends to not gall against steel if any lubrication is available. It might help to know the yield strength of the cast iron.
RE: Yield Strength and Wear Properties of Steel
The topic of steel availabilty should be affecting any product or service steel-related. It is a good comparison to the price of a gallon of gas. Products which rely on gas to get it to market is also impacted by the price of gas. This is public knowledge. Many manufacturers are now seeking alternative material specifications due to the rising cost and availabilty of metals.
Some of my clients are now looking for alternative materials for the very same reason that afarian is.
RE: Yield Strength and Wear Properties of Steel
I did not understand your positive slope comment in reference to hardness comparison. However it seems to me that difference in wearability between the 50ksi and 80ksi would be negligible in thisw application. As mentioned earlier, I would be looking at whether you need to increase material thickness otherwise why would 80 kis steel have been selected in the existing design? I suggest it was for strength rather than wear.
Jesus is THE life,
Leonard
RE: Yield Strength and Wear Properties of Steel
By positive slope relationship I meant that the higher the yield strength, the higher the hardness. In addition, there is a pretty strong correlation of this by the high R-squared value.
As for the selection of the 80ksi yield material, I can't seem to find a specific reason why that material was chosen to begin with. Perhaps not knowing any better coupled with the tiny price increase at the time was worth the insurance it provided someone here?!?
As for the increased thickness point you made, we have decided to go ahead and make that upgrade, since that is a small enough weight penalty. So in the end, our final decision is to go ahead with the 50ksi yield material and increase the thickness. Thank you all for your collective wisdom and help. I hope I can return the favor one day.
afarian