Engine Piston Pin Failure

The experts base their answer on general experience. 2 max (which by the way, could be referring to thin or thick inclusions, as defined by E45 - in general they talk about thick) is pretty conservative, and can be supplied by most of the serious steel mills today. As far the conditions, temperature and humidity do not affect the readings, per se. The best is, if you can't afford to hire a metallurgist (which is also a mentality problem with many American companies, and one of the not-so-minor reasons for which we fell behind technologically and can't compete on the market), to get the ASTM E45, Plate I-r, for instance, a polishing machine, some pads, a microscope - or just send your samples out to a lab. If the inclusion rating is more than 5 for you piston pins, change your supplier - you're buying scrap.

Titi-the-rabbit

Nice advice Mssr Titi the Rabbit.

I would only point out that the original poster has identified his inclusion as a slag inclusion, which would be the result of lack of process control and rejectable in an SBQ application.

If the OP erred in calling the inclusion slag, then the question really becomes What is the nature of the inclusion, and per E45, is it Sulfide, (type A) Aluminate(type B), Silicate (type c) or Globular oxides(type D).

In my QL-1 rated melt shop Our worst two areas were Type A thin (average 1.49, std deviation .55) and Type D Thin (average 1.63,std dev .35).

The type of inclusion is as much part of the engineering assessment for suitability for use as is the rating for type and frequency.

But if its slag inclusion, its not approriate for internal combustion engine applications.

The rabbit is right. Change your supplier- or your purchasing agent/ specification.

Milo

Thanks Milo. The nature of inclusion reported by the customer is Silicate type C.

However if one intends to check it at ones own end with a software; do the temprature & humidity have to controlled Since the supplier told to do so while polishing the specimen high humidity (80-90%) and temprature above 45 degree C

may contaminate the surface of the specimen resulting in erratic readings.

Thanks for the reply in advance.

Dont understand why your supplier is saying these things. Humidity is non issue since surface being polished is in contact with aqueous polishing compound on disc. 45 C is way too hot for worker safety and does nothing for the sample or polishing. All our met lab work was done in airconditioned controlled humidity lab target 72 F (22-24 C). No idea on humidity.

by software, you mean image analysis program?

Milo