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Wear Rate - Influencing factors and their weighted effects

Wear Rate - Influencing factors and their weighted effects

Wear Rate - Influencing factors and their weighted effects

(OP)
Good day all,

Without going into too much detail, I have a piston which reciprocates inside a hardened sleeve, lubricated by an oil/water mixture. The piston is a sacrificial part in the larger system and is manufactured with wear rings machined into the outer diameter. Once the rings are no longer visible, the piston is removed and replaced. The material grade from which we previously made this piston is no longer available, and we would like to make replace it with a cheaper, more readily available steel. I do not want the new material to wear at a lower rate than the old - it must wear at the same, or higher rate.

My basic understanding of wear rate is that:
1. Hardness is by far the most important factor in how much the piston will wear. Harder steel = less wear.
2. Micro-structure & Chemistry will play a minor role in how much the piston wears, independent of hardness.

Based on the above assumptions I have made, as long as the Hardness of the new material is lower than or equal to that of the old, there should be no issue.

tl;dr: In lubricated, sliding contact, (all other factors - surface finish, abrasive medium, etc the same) will the hardness of the materials in contact play the greatest role in determining wear rate, or are there other factors to be weary of?

RE: Wear Rate - Influencing factors and their weighted effects

What was the original material?
What is is it mated against?
The last thing that you want is to risk wear to the sleeve.
Are we to assume zero risk of corrosion, regardless of the material?
While hardness plays a dominant role when you change materials (microstructures) you will find significant shifts.
This is due to some materials having natural lubricity or work hardening significantly.
You can't compare the hardness of one alloy system to another, only within similar alloys.

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P.E. Metallurgy, consulting work welcomed

RE: Wear Rate - Influencing factors and their weighted effects

That is a little oversimplified. I think you have to start with the properties of the current material. Is wear resistance imparted by surface hardening (i.e. induction hardening). If so, what is the specified case depth and hardness requirements. What is the required core hardness? You need to use these properties to consider the material replacement and whether you can achieve them with the new material. The new material should be fairly similar to the old so you don't introduce other variable that could affect wear like different thermal expansion.

RE: Wear Rate - Influencing factors and their weighted effects

(OP)

Quote (edstainless)

Original material of the sacrificial part is S355JR, provided in the normalized condition. I would like to replace it with a fully annealed AISI 4130. The mating component is an API 5L X80 Pipe. Corrosion risk is not a major factor in this case.

RE: Wear Rate - Influencing factors and their weighted effects

Why not 1022? Since your original is just a plain steel.

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P.E. Metallurgy, consulting work welcomed

RE: Wear Rate - Influencing factors and their weighted effects

(OP)
We only have qualified WPS's in place for AISI 4130 to X80.

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