Carbon Steel "stamp": o.k. for marking ANY material? 1

[MotoGP]

I will ask, in advance, that you Material Engineer Gods have mercy upon my soul for asking, what will seem to you, to be such a "basic" question. The subject question relates to a carbon steel "stamp", carried by an inspector, that is to be utilized to make an impression marking (for identification purposes) in a material's surface.

The types of material to be marked are, presumptively, to be of infinite material composition, however, the most commonly marked material alloys would be those of either carbon steel, stainless steel or aluminum.

The "raised" portion of the stamp, that is, the area of the stamp that would mark the material surface, would leave its impression after having been forcibly struck.

The mark would have an approximate surface area of 2mm x 2mm that creates an approximate 1.5mm impression.

Could this stamp be used repeatedly, on any/all of the sufaces of the materials mentioned, without predisposing the marked material to a deleterious surface flaw?

Additionally, do you think that there should be any limitations imposed when the stamp is used, such as minimum distances from welded areas, changes in material surface contours, and the like?

 

[unclesyd]

This is just a general discussion that covers the basics so I would caution you that need to verify with any code, standards, or regulations that covers the end use of material as to where, when, and what information is required if stamped.

Hallmarks, makers marks, stencil lettering, and others have caused component failure by acting as a stress riser. These stress risers under the right conditions can become the initiation point for several modes of failure. Any book, especially older books, having pictures depicting different modes of failure will have examples showing a crack emitting from an indentation made by a stamp.
The potential problems with stamping can be minimized by making a stamp that has a smooth transition, in other words as close to a dimple or series of dimples as possible. Any type mark should have as smooth as possible transition from the indentation to surface.

A good general rule for fabricated components is that if a material is going to be heat treated don't stamp it in a place that is going see high sustained stress or alternating stresses in service or transitional stress in heat treating, especially water or oil quenching. This is in places near an edge, hole, change in section, etc.

Raw materials are different story. Low carbon steels we weren't very particular. Normally if stamped we would like to see dimpled stamps. On tools steels we allowed no impression stamping, only surface etch if identification was needed. On alloy steels we only liked to see dimpled stamping and with no more than the absolute minimum information required by a jurisdictional authority if the material was to be used in a pressure vessel. One steels used for pressure vessels there are specific requirements for identification marking and transfer of the identification mark as components are fabricated from the material. On some items like fasteners there are specific requirements.

 

[deanc]

Guidence-See ASME SecVIII Div1 UG-118