Page Index

Subject Index

Sponsors
Coyote Hunting
Coyote Calling Example
Coyote Attacks
Varmint Hunting
17 HMR Field Testing
Deer Hunting
Many Hunting Stories
Hunt Success Stories
Make A Bi-Fur-Pod
Reloading Page
Shooting Page
Free Targets
Powder Burn Rate
Fluted Barrel Analysis
22LR Rifle & Tuner
Esten's Rifle & Tuner
Light Rifle & Tuner
Barrel Harmonic Movie
Barrel Tuner Analysis
6PPC Barrel Dynamics
243 Model 7 Action FEA
Rifle Action Stress
Bat Action Analysis
Rifle Chamber Finish
Friction Test Results
Gun Rights & Politics
Bart our Black Lab
Tide son of Bart
Engineering Page
Rockwell Hardness FEA
Mini Lathe Page
My Computers Page
Ham Radio Page
Home Page
My Father
Bethel Island
Backpacking
Winnemucca Lake
Online Metal Orders
Make Your Web Page
Latest Updates
Links Page
Email

 

Rockwell C Hardness Test Simulation by Finite Element Analysis.

POWERFUL TOOL.... The NIKE2D Finite Element Code by Livermore Software Technology Corp is a very powerful 2-D tool for calculating the loads and deformations of axisymmetric structures. Often, I need to know the yield and ultimate stress of materials when given only the Rockwell C hardness. NIKE2D can be used to calculate the Rockwell C hardness of various materials in the material.txt data base. Being able to calculate the Rockwell C hardness of a steel is very useful in selecting the correct material properties for a material of interest.

THE MEASUREMENTS.... I have generated a 2-D FEA  model of the the Rockwell hardness testing procedure. The diamond cone, used for the Rockwell C hardness testing, has a 120 degree included angle with a 0.02 mm tip radius. In the calculation, the loading is identical to the actual test procedure. A 10 Kg load is applied to the diamond, the displacement if the diamond indenter is recorded and then the load is increased to 150 Kg. The load is then decreased back down to 10 Kg and the displacement of the diamond is again recorded. These two measurements are used to calculate the Rockwell C hardness. A friction coefficient of 0.2 is used between the diamond surface and the steel.

THE MATH.... The difference of the first 10 Kg load depth and the second 10 Kg depth, measured in millimeters divided by 0.002 mm and then subtracted from 100 is the Rockwell C hardness.

Rc = 100 - (Y2 - Y1) / 0.002


This is an animated movie of the Rockwell C Hardness test on
4340 Steel with a yield stress of 133,000 psi.

1. The diamond cone is loaded to 10 Kg and the vertical displacement is recorded (Y1).
2. The load is increased to 150 Kg, but the displacement is not recorded.
3. The load is decreased to 10 Kg and the vertical displacement is recorded (Y2).
4. The Rockwell Hardness C is calculated using Y1 and Y2.
5. The Rockwell Hardness is: Rc = 100 - (Y2 - Y1) / 0.002

Table 1: Hardness numbers for 4340 Steel in various heat treat conditions.

Steel 4340
Yield Stress
(psi)
Nominal
Rockwell C
Calculated
Rockwell C
u=0.2
Nominal
Brinell
Hardness
Calculated
Brinell
Hardness
69,000   13.07 217  
90,000 18 20.54 220  
121,000 27 28.65    
128,000 28* 29.12 270  
133,000   30.72    
135,000 28* 32.33 310  
150,000 37 35.07 340  
159,000 36 35.54    
170,000   39.70 380  
185,000 43 42.47 400  
200,000   43.69 430  
238,000   49.86 550  
         

u = 0.2 is the friction coefficient between the diamond and the test metal.
* The available data is obviously not very accurate in the midrange of yield stresses.


The Rc calculated hardness fits the available data reasonably well.

When time allows, I will generate another FEA model to calculate the Brinell hardness metals. I recently found data on 4140 steel and added it to the plot. The calculations were only for 4340 steel, but they look very similar.

Material Name and Condition.            Density Yng's Poiss  Yld   Ult  Elong Redu CTE   Yld
                                        lb/in^3 Modul Ratio  Strs  Strs   %   Area 10^-6 off-
                                                 msi         ksi   ksi         %   /degF set
steel wrought 4340 1 in. bar annealed    0.2830 30.00 0.290  69.0 108.0  22.0 50.0  6.30 0.20
steel wrought 4340 Case 1                0.2830 30.00 0.290  90.0 117.8  21.4 54.0  6.30 0.20
steel wrought 4340 Case 2                0.2830 30.00 0.290 128.0 143.2  18.4 56.0  6.30 0.20
steel wrought 4340 1 in. bar oq+1200f    0.2830 30.00 0.290 133.0 147.0  18.0 57.0  6.30 0.20
steel wrought 4340 Case 3                0.2830 30.00 0.290 135.0 149.1  17.7 54.0  6.30 0.20
steel wrought 4340 Case 4                0.2830 30.00 0.290 150.0 163.2  16.8 53.0  6.30 0.20
steel wrought 4340                       0.2840 29.70 0.290 159.0 165.0  16.5 54.1  6.83 0.20
steel wrought 4340 1 in. bar oq+1200f    0.2830 30.00 0.290 170.0 183.0  14.0 52.0  6.30 0.20 
steel wrought 4340 Case 5                0.2830 30.00 0.290 185.0 203.0  12.9 48.0  6.30 0.20
steel wrought 4340 1 in. bar oq+800f     0.2830 30.00 0.290 200.0 222.0  12.0 47.0  6.30 0.20
steel wrought 4340 1 in. bar oq+400f     0.2830 30.00 0.290 238.0 283.0  11.0 48.0  6.30 0.20
steel wrought 4140 1 in. bar annealed    0.2830 29.00 0.290  61.0  95.0  26.0 57.0  6.20 0.20
steel wrought 4140 1 in. bar norm        0.2830 29.00 0.290  95.0 148.0  18.0 47.0  6.20 0.20
steel wrought 4140 1 in. bar oq+1200f    0.2830 30.00 0.290  95.0 110.0  18.0 53.0  6.20 0.20
steel wrought 4140 1 in. bar oq+1000f    0.2830 30.00 0.290 143.0 165.0  15.0 50.0  6.20 0.20
steel wrought 4140 1 in. bar oq+400f     0.2830 30.00 0.290 238.0 257.0   8.0 38.0  6.20 0.20

Google
 
Web www.varmintal.com

Good Hunting... from Varmint Al
For the serious reader: How to Check Another Engineer's Calculation.

Vote for Us at The Outdoor Lodge's Top Hunting Sites

FinsandFur Top Sites - The best of Hunting and Fishing

Last Updated: 02/08/2013
End of Page