Fun with a hardness tester

[.RC.]

Greg recently sold me his hardness tester..... It is a Japanese made unit from 1974..

It measures Rockwell C and Rockwell B..

Here are some results from various things around the shop... All resuts are in HRC scale

CTC Tools HSS..various sizes 58

RIMET 1/4 square M42 HSS 65

Bohler 1/2" square HSS 65

Ridgid 1-2" universal pipe die HSS 60

Chinese HSS 4mm die 63

Old P&N die locally made 56

4140 round bar 1/2" 24

4140 round bar heated to orange colour and quenched in water no tempering 57

4140 bar heated to orange colour but 8mm away from the last test where the bar was cooler when quenched 23 (this one amazed me and it showed how critical the correct temperature for hardening is.. If it does not get hot enough, nothing changes)

Au made Sidchrome spanner 45

Teng tools spanner 44

generic spanner that comes with new cars 38

allen key 50

screwdriver 38

Quite an interesting array of hardnesses there...

[tea lady]

:D You didn't try the toaster and the butter knife.

Interesting list non the less. :cool:

[.RC.]

Well I did some Victorinox steak knives.... 53HRC and a NSK bearing.... 59HRC

[shedhappens]

Hi RC,

Interesting post, hardening is something that I will need to learn in the future.

Could you oil quench a sample of hot rolled steel and test it ?

Also do you have an oven and have you noted what sort and size of dimensional change's you get after heat treating ?

I seem to remember (years ago) that when we made shafts for hydraulic pumps motors and cylinders we did a final grind of .015' or .020 when they returned from the heat treater's.

thanks, john

[Jekyll and Hyde]

CTC Tools HSS..various sizes 58

RIMET 1/4 square M42 HSS 65

Bohler 1/2" square HSS 65



Those results I find quite interesting... I remember a thread some time ago where I commented that HSS (on the lathe) for me just didn't last on any steels, especially on interrupted cuts. The suggestion was made that CTC's HSS (all I have) tended to be a bit soft, and other brands held an edge much better - your testing would seem to prove that point!

[.RC.]

Hi RC,

Interesting post, hardening is something that I will need to learn in the future.

Could you oil quench a sample of hot rolled steel and test it ?

Also do you have an oven and have you noted what sort and size of dimensional change's you get after heat treating ?

I seem to remember (years ago) that when we made shafts for hydraulic pumps motors and cylinders we did a final grind of .015' or .020 when they returned from the heat treater's.

thanks, john

Mild steel hot rolled will not harden very much if heated and quenched, as it is only carbon in steel that allows steel to harden..... All the other alloys that are added only serve to change the characteristics of the quenching and tempering process...

I do have an oven but have not yet got around to using it...Other then testing it... It is only a small one...




Those results I find quite interesting... I remember a thread some time ago where I commented that HSS (on the lathe) for me just didn't last on any steels, especially on interrupted cuts. The suggestion was made that CTC's HSS (all I have) tended to be a bit soft, and other brands held an edge much better - your testing would seem to prove that point!

yes hardness would have a bit to do with it, but the elements added to HSS would probably probably be more important.... Take a file for example, you could use it as a lathe tool as it is hard, very hard, but it simply does not last as a cutting tool, as the temperature at the tool tip is quite hot due to the cutting friction and at elevated temperatures steel becomes softer, but elements like Tungsten and Molybdenum allow steel to be raised to higher temperatures before the tempering process begins..