Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


Piston pin

Piston pin

Piston pin

Hi all,
I'm trying to find a steel alloy piston (gudgeon, wrist) pin that is a rating of 70 HRC (760 brinell hardness).
This steel must be able to be processed through nitriding chemical process to emphasizing the hard wearing properties of the carbon in the steel to the surface.
Steel stable nitrides include chromium, molybdenum, aluminium, vanadium, tungsten and i believe nickle is one also.
Anyone got any ideas what alloys can achieve this hardness rating with out being like glass?

PS: Nice easy question for my everyone first question on here ha. Hope everyone is well.


RE: Piston pin

What is wrong with traditional nitriding grades (with Al)?
Their case hardness reaches over 1000HVN.
How deep of a case are you after?

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Piston pin

Hi Ed,
As Al wouldn't be great as i'm trying not to use DLC (diamond like carbon) coatings as it is expensive when producing a fair amount.
Al wouldn't give use the strength we need without DLC.
I'm trying to maximize on strength, minimize weight and cost.
I'm currently looking at the M2 molybdenum high speed tool steel.
Which is rated at 65 HRC before nitriding. Think this will do the job.
Unless one of the other M high speed tool steels would work better. M3-M10.
what do you think?

RE: Piston pin

what size do you need ?

It used to be that the thick paper engine parts catalogs behind the counter in every parts store included "progressive size" charts for most of the parts families.

Nowadays such info is a little harder to find.


RE: Piston pin

No, nitriding alloys are steel with Al in them. They use Cr, Mo, and V to strengthen the alloy, and the AlN to give surface hardness.
Virtually all tool steels are >RC60 when quenched and give a low temperature temper.
The problem with nitriding tool steels is that most of the nirtide forming elements are tied up in carbides, this is what makes them hard.
How are you going to nitride? low temp or higher temp? Ion?

P21 is an interesting grade. It is usually supplied Q&T at about 35RC, then after machining it is aged to reach 40RC in the core, and often given a low temp carburizing or nitriding treatment at the same time to raise surface hardness.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Piston pin

If your goal is wear resistance, include deep cryogenic treatment into your thermal treatment. This will increase the wear resistance considerably.

RE: Piston pin

Thanks for your help budding engineers, some points helped me get to the answer i was requiring.
I will try to help you all where and when i can

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Research Report - Mass Customization Placing Design in the Customers Hands
Products come in all shapes and sizes, and customers demand solutions tailored to their needs. With mass customization software, these two facts can be reconciled in an automated, customer-facing experience called a product configurator. In this engineering.com research report, we examine the different levels of mass customization with the pyramid of product configurators. Taking a look at real-world case studies, we discover how the highest level of the pyramid can enable true engineering automation, saving time and increasing customer satisfaction. Download Now
Research Report - Test and Simulation Survey
We at engineering.com continually hear how engineers and designers will be doing simulation, such as FEA and CFD, and that they will be doing it early in the design cycle. Is this wishful thinking? We found out what it is really like in industry. Read more now. Download Now
White Paper - Effects of AIA Quick Guide to UL 489 or UL 1077
The function of a circuit breaker is to provide overload (thermal) and short-circuit (magnetic) protection to a circuit and its downstream components. A circuit breaker functions like an airbag in a car, protecting circuit components and people by tripping the circuit to interrupt the current flow if it detects a fault condition in the control system. Download Now
White Paper - Guide to Integrate Large-Format Additive
As with any new technology, getting into large-format 3D printing begins with investigation. The first question may be a simple one: what does “large-format” mean? For 3D printers, “large” is a relative term. Many extrusion-based (FFF) 3D printers are referred to as desktop machines, because they fit on table space. Some of these have very respectable build volumes – but when it comes to “large-format,” the machines will need their own dedicated floor space. Large-format 3D printers have significant build volumes and are most often found in professional settings, like manufacturing facilities and R&D centers. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close