File Test for Work Hardened Steel

[tomwalz]

File Test for Work Hardened Steel

Saw steel for sawmills should be in the low Rockwell C about 40 – 45 roughly.

The heat from brazing the carbide tips to the steel saw plate can raise the hardness to somewhere in the low 60s Rc.

Saw steel also work hardens. The gullets will work hard after enough use.

Hard saw steel is likely to snap off in use. Saw steel with an outer hardness layer is likely to be a source of crack initiation and consequent ripping of the steel.

The current test for hardness is a round file test. An ordinary round file will slide across Rockwell C 60 steel. It will bite into Rockwell 40 steel.

Unfortunately, any sort of a test that causes any kind of an indentation in the steel is out of the question.

The file test, as it stands now, is pretty unsophisticated.

I would sincerely appreciate any comments anyone cared to make about the current test method or about the situation in general.

Sincerely,
Tom Walz


Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[btrueblood]

Does a rebound-type hardness tester leave an objectionable indent?

There was a post somewhere on this site where a poster wanted to use a hardness tester that few had heard of. Some European company had a hardness tester that worked on an (as near as could be determined from my admittedly brief look at their website) electrical resistivity principle. I'd think it hard (but not impossible) to calibrate electrical resistivity to hardness for a given alloy...might be worth a google search and a phone call.

 

[btrueblood]

hmm...maybe never mind Tom. Found this from a google search:

http://www.qs-hardnesstester.com/resistivity-hardness-testers.html

apparently, the electrical resistance is changing due to depth of penetration of the indenter, not bulk resistance change of the alloy due to cold working. Not sure if this is the same site or not, but it might be the same principle.

 

[metengr]

I have seen the file test used in many field applications where a hardness tester was not available. It is a qualitative comparison test and, as such, should be treated with caution. I have seen one of my associates in action that is aged as I am and did a decent job of hardness comparison before portable hardness testers were the norm.

 

[btrueblood]

There are a few scholarly articles that discuss magnetic permeability and/or eddy current dissipation measurements as correlated to hardness measurements.

Lastly, using the non-standard methods above, or some other direct measurement (does the thickness of the plate near the gullets increase as they work harden) - could you serialize the saw plate and keep a data log book for it, and track changes over time to indicate work hardening?

 

[Guest102023]

With the right file and file technician, it could work as a kind of go/no-go gauge, but no better.

 

[mrfailure]

I want to re-ask the question btrueblood started with: is a rebound tester really out of the question? It does leave a very shallow dent but I have used Equotip and Leeb testers without this damaging the integrity of the test part.

Aaron Tanzer

http://www.lehightesting.com