Nick Mueller wrote:
David Billington wrote:


The 1st figure is 1/10 the tensile strength and 2nd figure is 1/10 the
ratio between the minimum tensile strength and the minimum yield stress
(or proof stress in the higher strength fasteners as this is), also IIRC
the units are in kgf/mm2. So the yield stress is 90 kgf/mm2 and the
tensile strength is 100kgf/mm2.


Grade 10.9 means:
tensile strength is 100 kp / mm^2 (there is no such thing as kgf)

I ran across kgf not being an official unit the other day but still
widely used in some places. The tensile and compressive test stand
software I work on sometimes supports kgf, gf, as well as N, kN, MPa,
kPa, N/mm^2, lbf and a few others. The N/mm^2 was added recently to suit
customer demand, although it is equivalent to kPa, some customers knew
that but still asked for N/mm^2 as that was what they were used to.
Likewise some parts of the world still use kgf.

What is the status of daN. I have run across it a few times before and
finally looks it up, as I didn't know what it was, decanewton 1daN =
10N. Now the data sheets make sense.

Multiplying the first number with the second (10 * 9 = 900) gives the yield
strength times 10 (so 90 kp / mm ^2).

A 8.8 has 80 kp/mm^2 tensile and 64 kp/mm^2 yield strength.
The numbers aren't very precise.
That was the initial definition. Of course, the units now are in N and mm,
or in Pa.


Nick