Clamping blades straight after interrupted quench

Interesting ideas, good to know other people are doing this too and that I'm not compromising my steel this way! Especially considering how effective it seems at preventing warpage.

Stacy I like the idea of using angle iron, seems simple and easy and can be sat in the jaws of a vice. But maybe clamps are better for addressing distal taper? Curious to see your setup too RangerBobTX. For clamping to account for distal taper, I guess it would be best to put the tip of the blade at the far end of the angle iron, clamp there first, then at the halfway point next (establishing the angle of the distal taper of the blade within the clamping jig) and last at the tang/handle right?

Regarding cooling rate and how it's affected by clamping post-quench: If it's a matter of having the slowest cooling between 900f and 500f, could it then also be beneficial to preheat the steel of the clamping jig so that it didn't draw the heat out of the blade so quickly? Less of a shock to the blade steel... clamping jig and blade could cool down at the same time more slowly.

I should probably say I'm working with O1 and it seems to stay flexible for nearly a minute out of quench, so there's quite a long window of time for getting it clamped up while the Martensite is forming.
 
Nickandersonart,

I'm working with O1 as well and I'm fascinated by the heat transfers involved in quenching (finally found a use for this stuff that I learned in undergrad) so I wrote up some simulations to calculate the approximate cooling rate.

If you would like, I could provide you some data on still air cooling for O1. I just need the dimensions approximated to a flat bar, start temperature, surrounding temperature. Let me know.
 
For most oil quenching steels I like to go from just below the oil smoking point then transfer to plates.

There is no way I'm going to straighten a blade right after quench by hand! There is not really a good way to tell when you have reached that point in which it will break.

I believe that in general it is better to straighten at a high temp then stress relieve or cycle the steel before another quench. Why not just re heat treat if possible then waste time with a warped blade?

I mostly use air hardening steels and make folders. I clamp everything together in temper to get them as straight as possible.

Shims during temper are a great way to reduce minor warpage often seen on larger fixed blades.

I grind everything besides water hardening steels post heat treat, that way warpage is reduced and if there is a warp it ii much easier to fix.
 
Hey duurza that would be really cool to see! I'm working with a lot of stock in the vicinity of 6mm (let's say around .25 inches). Start temperature I guess would probably be austenite temp, I'm using 1500, surrounding temperature I'd say is 85-90 degrees Fahrenheit (around 33c) on average


Sent from my iPad using Tapatalk
 
nickandersonart said:
Hey duurza that would be really cool to see! I'm working with a lot of stock in the vicinity of 6mm (let's say around .25 inches). Start temperature I guess would probably be austenite temp, I'm using 1500, surrounding temperature I'd say is 85-90 degrees Fahrenheit (around 33c) on average


Sent from my iPad using Tapatalk
Click to expand...

Since you didn't provide a length or width, I assumed 6 inches long and 1 inch wide with a thickness of 6 mm. Here's what my program spewed out.

hTotal = total heat transfer coefficient in W/m^2 K (combined of all modes, here I assumed there is radiation and natural convection of air with the blade)
hRadiation = heat transfer coefficient of just radiation (same units as above) - based on temperature difference and surface area
hVerticalNaturalConvection = heat transfer coefficient of air getting heated and moving across the surface of the blade (blade is edge down and parallel to the ground)

Biot # = ratio of heat transfer at the surface vs internal thermal conduction. If this number is less than 0.1 (conduction is 10x stronger than surface loss, it is safe to assume that the entire piece will be at one temperature)


[Time] [Temperature] [Total Heat Transfer Coefficient] [Biot #] {[h Radiation][h Vertical Natural Convection]}

[0.00 s] [816 C (1500 F)] [hTotal 115.82] [Bi 0.011] {[100.84][14.99]}
[5.00 s] [792 C (1457 F)] [hTotal 110.11] [Bi 0.011] {[95.17][14.94]}
[10.00 s] [774 C (1424 F)] [hTotal 105.87] [Bi 0.010] {[90.96][14.90]}
[15.00 s] [759 C (1397 F)] [hTotal 102.45] [Bi 0.010] {[87.58][14.87]}
[20.00 s] [746 C (1374 F)] [hTotal 99.58] [Bi 0.009] {[84.73][14.85]}
[25.00 s] [734 C (1353 F)] [hTotal 97.09] [Bi 0.009] {[82.27][14.83]}
[30.00 s] [724 C (1334 F)] [hTotal 94.87] [Bi 0.009] {[80.07][14.81]}
[35.00 s] [713 C (1316 F)] [hTotal 92.69] [Bi 0.008] {[77.91][14.78]}
[40.00 s] [703 C (1297 F)] [hTotal 90.52] [Bi 0.008] {[75.77][14.75]}
[45.00 s] [692 C (1277 F)] [hTotal 88.35] [Bi 0.008] {[73.62][14.73]}
[50.00 s] [681 C (1257 F)] [hTotal 86.17] [Bi 0.007] {[71.47][14.70]}
[55.00 s] [670 C (1237 F)] [hTotal 83.99] [Bi 0.007] {[69.31][14.67]}
[60.00 s] [658 C (1216 F)] [hTotal 81.78] [Bi 0.007] {[67.14][14.64]}
[65.00 s] [646 C (1194 F)] [hTotal 79.55] [Bi 0.006] {[64.94][14.61]}
[70.00 s] [633 C (1172 F)] [hTotal 77.27] [Bi 0.006] {[62.69][14.58]}
[75.00 s] [620 C (1148 F)] [hTotal 74.99] [Bi 0.006] {[60.44][14.55]}
[80.00 s] [608 C (1126 F)] [hTotal 72.85] [Bi 0.006] {[58.34][14.51]}
[85.00 s] [596 C (1105 F)] [hTotal 70.84] [Bi 0.005] {[56.37][14.47]}
[90.00 s] [585 C (1084 F)] [hTotal 68.96] [Bi 0.005] {[54.52][14.43]}
[95.00 s] [574 C (1064 F)] [hTotal 67.18] [Bi 0.005] {[52.79][14.40]}
[100.00 s] [563 C (1045 F)] [hTotal 65.51] [Bi 0.005] {[51.15][14.36]}
[105.00 s] [553 C (1027 F)] [hTotal 63.94] [Bi 0.005] {[49.61][14.33]}
[110.00 s] [543 C (1009 F)] [hTotal 62.45] [Bi 0.004] {[48.15][14.29]}
[115.00 s] [534 C (992 F)] [hTotal 61.04] [Bi 0.004] {[46.78][14.26]}
[120.00 s] [524 C (976 F)] [hTotal 59.70] [Bi 0.004] {[45.47][14.23]}
[125.00 s] [516 C (960 F)] [hTotal 58.43] [Bi 0.004] {[44.24][14.20]}
[130.00 s] [507 C (944 F)] [hTotal 57.22] [Bi 0.004] {[43.06][14.16]}
[135.00 s] [499 C (929 F)] [hTotal 56.07] [Bi 0.004] {[41.95][14.12]}
[140.00 s] [491 C (915 F)] [hTotal 54.97] [Bi 0.004] {[40.88][14.09]}
[145.00 s] [483 C (901 F)] [hTotal 53.93] [Bi 0.004] {[39.87][14.05]}
[150.00 s] [475 C (887 F)] [hTotal 52.93] [Bi 0.003] {[38.91][14.02]}
[155.00 s] [468 C (874 F)] [hTotal 51.98] [Bi 0.003] {[37.99][13.99]}
[160.00 s] [461 C (861 F)] [hTotal 51.07] [Bi 0.003] {[37.11][13.96]}
[165.00 s] [454 C (849 F)] [hTotal 50.20] [Bi 0.003] {[36.27][13.93]}
[170.00 s] [447 C (837 F)] [hTotal 49.36] [Bi 0.003] {[35.47][13.90]}
[175.00 s] [441 C (825 F)] [hTotal 48.56] [Bi 0.003] {[34.70][13.87]}
[180.00 s] [434 C (813 F)] [hTotal 47.80] [Bi 0.003] {[33.96][13.84]}
[185.00 s] [428 C (802 F)] [hTotal 47.06] [Bi 0.003] {[33.25][13.81]}
[190.00 s] [422 C (791 F)] [hTotal 46.35] [Bi 0.003] {[32.57][13.78]}
[195.00 s] [416 C (780 F)] [hTotal 45.66] [Bi 0.003] {[31.92][13.75]}
[200.00 s] [410 C (770 F)] [hTotal 45.00] [Bi 0.003] {[31.29][13.71]}
[205.00 s] [405 C (760 F)] [hTotal 44.37] [Bi 0.003] {[30.69][13.68]}
[210.00 s] [399 C (750 F)] [hTotal 43.75] [Bi 0.003] {[30.11][13.65]}
[215.00 s] [394 C (741 F)] [hTotal 43.16] [Bi 0.003] {[29.55][13.61]}
[220.00 s] [389 C (731 F)] [hTotal 42.59] [Bi 0.002] {[29.01][13.58]}
[225.00 s] [383 C (722 F)] [hTotal 42.04] [Bi 0.002] {[28.49][13.55]}
[230.00 s] [378 C (713 F)] [hTotal 41.51] [Bi 0.002] {[27.99][13.52]}
[235.00 s] [374 C (704 F)] [hTotal 40.99] [Bi 0.002] {[27.50][13.49]}
[240.00 s] [369 C (696 F)] [hTotal 40.50] [Bi 0.002] {[27.04][13.46]}
[245.00 s] [364 C (687 F)] [hTotal 40.02] [Bi 0.002] {[26.59][13.43]}
[250.00 s] [360 C (679 F)] [hTotal 39.55] [Bi 0.002] {[26.15][13.40]}
[255.00 s] [355 C (671 F)] [hTotal 39.10] [Bi 0.002] {[25.73][13.37]}
[260.00 s] [351 C (663 F)] [hTotal 38.66] [Bi 0.002] {[25.32][13.34]}
[265.00 s] [347 C (655 F)] [hTotal 38.24] [Bi 0.002] {[24.93][13.32]}
[270.00 s] [342 C (648 F)] [hTotal 37.83] [Bi 0.002] {[24.54][13.29]}
[275.00 s] [338 C (641 F)] [hTotal 37.43] [Bi 0.002] {[24.17][13.26]}
[280.00 s] [334 C (633 F)] [hTotal 37.05] [Bi 0.002] {[23.81][13.23]}
[285.00 s] [330 C (626 F)] [hTotal 36.67] [Bi 0.002] {[23.47][13.21]}
[290.00 s] [326 C (619 F)] [hTotal 36.31] [Bi 0.002] {[23.13][13.18]}
[295.00 s] [323 C (612 F)] [hTotal 35.96] [Bi 0.002] {[22.80][13.16]}
[300.00 s] [319 C (606 F)] [hTotal 35.61] [Bi 0.002] {[22.48][13.13]}
[305.00 s] [315 C (599 F)] [hTotal 35.27] [Bi 0.002] {[22.17][13.10]}
[310.00 s] [312 C (593 F)] [hTotal 34.94] [Bi 0.002] {[21.87][13.07]}
[315.00 s] [308 C (586 F)] [hTotal 34.62] [Bi 0.002] {[21.58][13.04]}
[320.00 s] [305 C (580 F)] [hTotal 34.31] [Bi 0.002] {[21.30][13.01]}
[325.00 s] [301 C (574 F)] [hTotal 34.00] [Bi 0.002] {[21.02][12.98]}
[330.00 s] [298 C (568 F)] [hTotal 33.71] [Bi 0.002] {[20.75][12.95]}
[335.00 s] [295 C (562 F)] [hTotal 33.42] [Bi 0.002] {[20.49][12.93]}
[340.00 s] [292 C (557 F)] [hTotal 33.14] [Bi 0.002] {[20.24][12.90]}
[345.00 s] [288 C (551 F)] [hTotal 32.87] [Bi 0.002] {[19.99][12.87]}
[350.00 s] [285 C (545 F)] [hTotal 32.60] [Bi 0.002] {[19.75][12.85]}
[355.00 s] [282 C (540 F)] [hTotal 32.34] [Bi 0.002] {[19.52][12.82]}
[360.00 s] [279 C (535 F)] [hTotal 32.08] [Bi 0.002] {[19.29][12.79]}
[365.00 s] [276 C (529 F)] [hTotal 31.84] [Bi 0.002] {[19.07][12.77]}
[370.00 s] [274 C (524 F)] [hTotal 31.59] [Bi 0.002] {[18.85][12.74]}
[375.00 s] [271 C (519 F)] [hTotal 31.36] [Bi 0.002] {[18.64][12.72]}
[380.00 s] [268 C (514 F)] [hTotal 31.12] [Bi 0.002] {[18.43][12.69]}
[385.00 s] [265 C (509 F)] [hTotal 30.90] [Bi 0.002] {[18.23][12.66]}
[390.00 s] [262 C (504 F)] [hTotal 30.68] [Bi 0.002] {[18.04][12.64]}
[395.00 s] [260 C (499 F)] [hTotal 30.46] [Bi 0.002] {[17.85][12.61]}
[400.00 s] [257 C (495 F)] [hTotal 30.25] [Bi 0.002] {[17.66][12.59]}
[405.00 s] [255 C (490 F)] [hTotal 30.04] [Bi 0.002] {[17.48][12.57]}
[410.00 s] [252 C (486 F)] [hTotal 29.84] [Bi 0.001] {[17.30][12.54]}
[415.00 s] [250 C (481 F)] [hTotal 29.64] [Bi 0.001] {[17.12][12.52]}
[420.00 s] [247 C (477 F)] [hTotal 29.45] [Bi 0.001] {[16.95][12.49]}
[425.00 s] [245 C (472 F)] [hTotal 29.26] [Bi 0.001] {[16.79][12.47]}
[430.00 s] [242 C (468 F)] [hTotal 29.07] [Bi 0.001] {[16.63][12.45]}
[435.00 s] [240 C (464 F)] [hTotal 28.89] [Bi 0.001] {[16.47][12.42]}
[440.00 s] [238 C (460 F)] [hTotal 28.71] [Bi 0.001] {[16.31][12.40]}
[445.00 s] [235 C (456 F)] [hTotal 28.53] [Bi 0.001] {[16.16][12.38]}
[450.00 s] [233 C (452 F)] [hTotal 28.36] [Bi 0.001] {[16.01][12.35]}
[455.00 s] [231 C (448 F)] [hTotal 28.19] [Bi 0.001] {[15.87][12.33]}
[460.00 s] [229 C (444 F)] [hTotal 28.03] [Bi 0.001] {[15.72][12.31]}
[465.00 s] [227 C (440 F)] [hTotal 27.87] [Bi 0.001] {[15.58][12.28]}
[470.00 s] [225 C (436 F)] [hTotal 27.71] [Bi 0.001] {[15.45][12.26]}
[475.00 s] [223 C (432 F)] [hTotal 27.55] [Bi 0.001] {[15.31][12.24]}
[480.00 s] [220 C (429 F)] [hTotal 27.40] [Bi 0.001] {[15.18][12.21]}
[485.00 s] [218 C (425 F)] [hTotal 27.24] [Bi 0.001] {[15.06][12.19]}
[490.00 s] [216 C (421 F)] [hTotal 27.09] [Bi 0.001] {[14.93][12.16]}
[495.00 s] [215 C (418 F)] [hTotal 26.94] [Bi 0.001] {[14.81][12.13]}
[500.00 s] [213 C (414 F)] [hTotal 26.80] [Bi 0.001] {[14.69][12.11]}
[505.00 s] [211 C (411 F)] [hTotal 26.65] [Bi 0.001] {[14.57][12.08]}
[510.00 s] [209 C (408 F)] [hTotal 26.51] [Bi 0.001] {[14.45][12.06]}
[515.00 s] [207 C (404 F)] [hTotal 26.37] [Bi 0.001] {[14.34][12.03]}
[520.00 s] [205 C (401 F)] [hTotal 26.24] [Bi 0.001] {[14.23][12.01]}
[525.00 s] [203 C (398 F)] [hTotal 26.11] [Bi 0.001] {[14.12][11.98]}
[530.00 s] [202 C (395 F)] [hTotal 25.97] [Bi 0.001] {[14.01][11.96]}
[535.00 s] [200 C (391 F)] [hTotal 25.85] [Bi 0.001] {[13.91][11.94]}
[540.00 s] [198 C (388 F)] [hTotal 25.72] [Bi 0.001] {[13.81][11.91]}
[545.00 s] [196 C (385 F)] [hTotal 25.59] [Bi 0.001] {[13.71][11.89]}
[550.00 s] [195 C (382 F)] [hTotal 25.47] [Bi 0.001] {[13.61][11.86]}
[555.00 s] [193 C (379 F)] [hTotal 25.35] [Bi 0.001] {[13.51][11.84]}
[560.00 s] [191 C (376 F)] [hTotal 25.23] [Bi 0.001] {[13.42][11.82]}
[565.00 s] [190 C (373 F)] [hTotal 25.11] [Bi 0.001] {[13.32][11.79]}
[570.00 s] [188 C (370 F)] [hTotal 25.00] [Bi 0.001] {[13.23][11.77]}
[575.00 s] [187 C (368 F)] [hTotal 24.89] [Bi 0.001] {[13.14][11.75]}
[580.00 s] [185 C (365 F)] [hTotal 24.77] [Bi 0.001] {[13.05][11.72]}
[585.00 s] [184 C (362 F)] [hTotal 24.66] [Bi 0.001] {[12.97][11.70]}
[590.00 s] [182 C (359 F)] [hTotal 24.56] [Bi 0.001] {[12.88][11.68]}
[595.00 s] [181 C (357 F)] [hTotal 24.45] [Bi 0.001] {[12.80][11.65]}
[600.00 s] [179 C (354 F)] [hTotal 24.35] [Bi 0.001] {[12.71][11.63]}


More details on the program:

Given a surface temperature, it calculates the heat transfer ratio of all modes available and attributes that much energy loss to the object. Using this energy loss, it recalculates all of the properties of the object (thermal conduction, specific heat and all of the other temperature dependent properties) over a given time period. The time period used here was 1 ms. It repeats this over and over again in smaller intervals to get a better approximation.

Radiation and Convection are easy because they don't involve phase changes such as water/oil quenching though it would be theoretically possible for me to incorporate those modes. I am actually think of adding plate quenching (more general - heat loss due to heat sink) and see what I would get.
 
For most all steels, you have nearly 30 seconds to hand straighten the blade after it clears the pearlite window. The drop in still air to Ms from 900F is a lot slower than most think, as shown by the above chart.
 
I straighten carbon steels with an interrupted quench when it passed the nose, but I always used the aluminum plates I use for stainless steel, it works when the bend is on the axis of the blade from tip to handle, but for wide blades, for example a thin chinese cleaver, where the bending sometimes appear on the spine to edge axis the cooling rate that aluminum provides is too fast to straighten, no matter how heavy the weight you put on top of the plates.

Now that I think about it, better than aluminum or carbon steel, the best not expensive and very doable solution is to use stainless steel plates, it has 1/3 of the heat conductivity of carbon steel.

Anyone tried stainless steel plates for delaying the cooling rate?


Pablo
 
duurza said:
If you would like, I could provide you some data on still air cooling for O1. I just need the dimensions approximated to a flat bar, start temperature, surrounding temperature. Let me know.
Click to expand...

I would be delighted to know this, I mostly use O2 for carbon steels, mostly in the 1.5mm (1/16") to 3mm (1/8") in the kitchen knives range of sizes, say 300x50x2.5mm (10"x2"x3/32")

Is there a program I can download to make these calculations myself? THANKS!!


Pablo
 
PEU said:
I would be delighted to know this, I mostly use O2 for carbon steels, mostly in the 1.5mm (1/16") to 3mm (1/8") in the kitchen knives range of sizes, say 300x50x2.5mm (10"x2"x3/32")

Is there a program I can download to make these calculations myself? THANKS!!


Pablo
Click to expand...

I wrote the program myself after I couldn't find one either. I used your dimensions of 300x50x2.5. I don't know what the hardening temperature is for O2 so I just started at 900 C. Just pick the approximate starting temp below 900 C and adjust for time.

[Time] [Temperature] [Total Heat Transfer Coefficient] [Biot #] {[h Radiation][hVertical Natural Convection]}

[0.00 s] [900 C (1652 F)] [hTotal 135.21] [Bi 0.006] {[122.95][12.26]}
[1.00 s] [881 C (1617 F)] [hTotal 129.86] [Bi 0.006] {[117.62][12.24]}
[2.00 s] [862 C (1584 F)] [hTotal 124.97] [Bi 0.005] {[112.74][12.23]}
[3.00 s] [845 C (1553 F)] [hTotal 120.48] [Bi 0.005] {[108.27][12.21]}
[4.00 s] [829 C (1524 F)] [hTotal 116.34] [Bi 0.005] {[104.14][12.20]}
[5.00 s] [814 C (1498 F)] [hTotal 112.76] [Bi 0.005] {[100.58][12.18]}
[6.00 s] [803 C (1476 F)] [hTotal 109.88] [Bi 0.004] {[97.71][12.16]}
[7.00 s] [792 C (1458 F)] [hTotal 107.44] [Bi 0.004] {[95.29][12.15]}
[8.00 s] [783 C (1442 F)] [hTotal 105.32] [Bi 0.004] {[93.18][12.14]}
[9.00 s] [775 C (1427 F)] [hTotal 103.43] [Bi 0.004] {[91.31][12.12]}
[10.00 s] [768 C (1414 F)] [hTotal 101.73] [Bi 0.004] {[89.61][12.11]}
[11.00 s] [761 C (1401 F)] [hTotal 100.17] [Bi 0.004] {[88.07][12.10]}
[12.00 s] [754 C (1390 F)] [hTotal 98.74] [Bi 0.004] {[86.65][12.09]}
[13.00 s] [748 C (1379 F)] [hTotal 97.42] [Bi 0.004] {[85.33][12.09]}
[14.00 s] [743 C (1369 F)] [hTotal 96.18] [Bi 0.004] {[84.10][12.08]}
[15.00 s] [737 C (1359 F)] [hTotal 95.02] [Bi 0.004] {[82.95][12.07]}
[16.00 s] [732 C (1350 F)] [hTotal 93.93] [Bi 0.004] {[81.86][12.06]}
[17.00 s] [727 C (1341 F)] [hTotal 92.90] [Bi 0.004] {[80.84][12.06]}
[18.00 s] [723 C (1332 F)] [hTotal 91.88] [Bi 0.003] {[79.83][12.05]}
[19.00 s] [718 C (1324 F)] [hTotal 90.87] [Bi 0.003] {[78.83][12.04]}
[20.00 s] [713 C (1315 F)] [hTotal 89.86] [Bi 0.003] {[77.83][12.03]}
[25.00 s] [688 C (1270 F)] [hTotal 84.82] [Bi 0.003] {[72.83][11.99]}
[30.00 s] [662 C (1223 F)] [hTotal 79.75] [Bi 0.003] {[67.81][11.94]}
[35.00 s] [633 C (1171 F)] [hTotal 74.56] [Bi 0.002] {[62.67][11.89]}
[40.00 s] [604 C (1119 F)] [hTotal 69.51] [Bi 0.002] {[57.69][11.82]}
[45.00 s] [578 C (1072 F)] [hTotal 65.17] [Bi 0.002] {[53.41][11.76]}
[50.00 s] [554 C (1028 F)] [hTotal 61.40] [Bi 0.002] {[49.71][11.69]}
[55.00 s] [531 C (988 F)] [hTotal 58.10] [Bi 0.002] {[46.46][11.64]}
[60.00 s] [511 C (952 F)] [hTotal 55.18] [Bi 0.002] {[43.61][11.58]}
[65.00 s] [492 C (918 F)] [hTotal 52.59] [Bi 0.001] {[41.07][11.51]}
[70.00 s] [475 C (886 F)] [hTotal 50.26] [Bi 0.001] {[38.81][11.45]}
[75.00 s] [458 C (856 F)] [hTotal 48.18] [Bi 0.001] {[36.78][11.40]}
[80.00 s] [443 C (829 F)] [hTotal 46.30] [Bi 0.001] {[34.95][11.34]}
[85.00 s] [428 C (803 F)] [hTotal 44.59] [Bi 0.001] {[33.29][11.29]}
[90.00 s] [415 C (778 F)] [hTotal 43.02] [Bi 0.001] {[31.79][11.23]}
[95.00 s] [402 C (755 F)] [hTotal 41.59] [Bi 0.001] {[30.41][11.17]}
[100.00 s] [390 C (734 F)] [hTotal 40.27] [Bi 0.001] {[29.15][11.12]}
[105.00 s] [378 C (713 F)] [hTotal 39.05] [Bi 0.001] {[27.99][11.06]}
[110.00 s] [368 C (694 F)] [hTotal 37.93] [Bi 0.001] {[26.92][11.01]}
[115.00 s] [357 C (675 F)] [hTotal 36.89] [Bi 0.001] {[25.94][10.96]}
[120.00 s] [348 C (657 F)] [hTotal 35.93] [Bi 0.001] {[25.02][10.90]}
[125.00 s] [338 C (641 F)] [hTotal 35.03] [Bi 0.001] {[24.17][10.86]}
[130.00 s] [329 C (624 F)] [hTotal 34.19] [Bi 0.001] {[23.38][10.81]}
[135.00 s] [321 C (609 F)] [hTotal 33.40] [Bi 0.001] {[22.64][10.76]}
[140.00 s] [313 C (595 F)] [hTotal 32.66] [Bi 0.001] {[21.95][10.71]}
[145.00 s] [305 C (580 F)] [hTotal 31.96] [Bi 0.001] {[21.31][10.65]}
[150.00 s] [297 C (567 F)] [hTotal 31.31] [Bi 0.001] {[20.70][10.60]}
[155.00 s] [290 C (554 F)] [hTotal 30.69] [Bi 0.001] {[20.13][10.56]}
[160.00 s] [283 C (542 F)] [hTotal 30.11] [Bi 0.001] {[19.60][10.51]}
[165.00 s] [277 C (530 F)] [hTotal 29.55] [Bi 0.001] {[19.09][10.46]}
[170.00 s] [270 C (518 F)] [hTotal 29.03] [Bi 0.001] {[18.62][10.41]}
[175.00 s] [264 C (507 F)] [hTotal 28.54] [Bi 0.001] {[18.17][10.37]}
[180.00 s] [258 C (497 F)] [hTotal 28.07] [Bi 0.001] {[17.74][10.32]}
[185.00 s] [253 C (487 F)] [hTotal 27.62] [Bi 0.001] {[17.34][10.28]}
[190.00 s] [247 C (477 F)] [hTotal 27.19] [Bi 0.001] {[16.96][10.24]}
[195.00 s] [242 C (467 F)] [hTotal 26.79] [Bi 0.001] {[16.59][10.19]}
[200.00 s] [237 C (458 F)] [hTotal 26.40] [Bi 0.001] {[16.25][10.15]}
[205.00 s] [232 C (449 F)] [hTotal 26.03] [Bi 0.001] {[15.92][10.11]}
[210.00 s] [227 C (440 F)] [hTotal 25.67] [Bi 0.001] {[15.61][10.07]}
[215.00 s] [222 C (432 F)] [hTotal 25.34] [Bi 0.001] {[15.31][10.03]}
[220.00 s] [218 C (424 F)] [hTotal 25.00] [Bi 0.000] {[15.02][9.98]}
[225.00 s] [214 C (416 F)] [hTotal 24.69] [Bi 0.000] {[14.75][9.93]}
[230.00 s] [209 C (409 F)] [hTotal 24.38] [Bi 0.000] {[14.49][9.89]}
[235.00 s] [205 C (401 F)] [hTotal 24.09] [Bi 0.000] {[14.24][9.84]}
[240.00 s] [201 C (394 F)] [hTotal 23.81] [Bi 0.000] {[14.01][9.80]}
[245.00 s] [198 C (387 F)] [hTotal 23.54] [Bi 0.000] {[13.78][9.76]}
[250.00 s] [194 C (381 F)] [hTotal 23.27] [Bi 0.000] {[13.56][9.71]}
[255.00 s] [190 C (374 F)] [hTotal 23.02] [Bi 0.000] {[13.35][9.67]}
[260.00 s] [187 C (368 F)] [hTotal 22.78] [Bi 0.000] {[13.15][9.63]}
[265.00 s] [183 C (362 F)] [hTotal 22.55] [Bi 0.000] {[12.96][9.59]}
[270.00 s] [180 C (356 F)] [hTotal 22.32] [Bi 0.000] {[12.78][9.54]}
[275.00 s] [177 C (350 F)] [hTotal 22.10] [Bi 0.000] {[12.60][9.50]}
[280.00 s] [174 C (345 F)] [hTotal 21.89] [Bi 0.000] {[12.43][9.46]}
[285.00 s] [171 C (339 F)] [hTotal 21.69] [Bi 0.000] {[12.26][9.42]}
[290.00 s] [168 C (334 F)] [hTotal 21.49] [Bi 0.000] {[12.11][9.38]}
[295.00 s] [165 C (329 F)] [hTotal 21.30] [Bi 0.000] {[11.95][9.34]}
[300.00 s] [162 C (324 F)] [hTotal 21.11] [Bi 0.000] {[11.81][9.30]}
[305.00 s] [160 C (319 F)] [hTotal 20.93] [Bi 0.000] {[11.66][9.27]}
[310.00 s] [157 C (314 F)] [hTotal 20.76] [Bi 0.000] {[11.53][9.23]}
[315.00 s] [154 C (309 F)] [hTotal 20.59] [Bi 0.000] {[11.40][9.19]}
[320.00 s] [152 C (305 F)] [hTotal 20.42] [Bi 0.000] {[11.27][9.15]}
[325.00 s] [149 C (301 F)] [hTotal 20.26] [Bi 0.000] {[11.15][9.12]}
[330.00 s] [147 C (296 F)] [hTotal 20.11] [Bi 0.000] {[11.03][9.08]}
[335.00 s] [145 C (292 F)] [hTotal 19.96] [Bi 0.000] {[10.91][9.04]}
[340.00 s] [142 C (288 F)] [hTotal 19.81] [Bi 0.000] {[10.80][9.01]}
[345.00 s] [140 C (284 F)] [hTotal 19.66] [Bi 0.000] {[10.69][8.97]}
[350.00 s] [138 C (280 F)] [hTotal 19.53] [Bi 0.000] {[10.59][8.93]}
[355.00 s] [136 C (276 F)] [hTotal 19.39] [Bi 0.000] {[10.49][8.90]}
[360.00 s] [134 C (273 F)] [hTotal 19.26] [Bi 0.000] {[10.39][8.86]}
[365.00 s] [132 C (269 F)] [hTotal 19.13] [Bi 0.000] {[10.30][8.83]}
[370.00 s] [130 C (266 F)] [hTotal 19.00] [Bi 0.000] {[10.21][8.79]}
[375.00 s] [128 C (262 F)] [hTotal 18.88] [Bi 0.000] {[10.12][8.76]}
[380.00 s] [126 C (259 F)] [hTotal 18.76] [Bi 0.000] {[10.03][8.73]}
[385.00 s] [124 C (256 F)] [hTotal 18.64] [Bi 0.000] {[9.95][8.69]}
[390.00 s] [123 C (252 F)] [hTotal 18.53] [Bi 0.000] {[9.87][8.66]}
[395.00 s] [121 C (249 F)] [hTotal 18.41] [Bi 0.000] {[9.79][8.62]}
[400.00 s] [119 C (246 F)] [hTotal 18.30] [Bi 0.000] {[9.71][8.59]}
[405.00 s] [118 C (243 F)] [hTotal 18.19] [Bi 0.000] {[9.64][8.55]}
[410.00 s] [116 C (240 F)] [hTotal 18.09] [Bi 0.000] {[9.57][8.52]}
[415.00 s] [114 C (238 F)] [hTotal 17.98] [Bi 0.000] {[9.50][8.49]}
[420.00 s] [113 C (235 F)] [hTotal 17.88] [Bi 0.000] {[9.43][8.45]}
[425.00 s] [111 C (232 F)] [hTotal 17.78] [Bi 0.000] {[9.36][8.42]}
[430.00 s] [110 C (229 F)] [hTotal 17.69] [Bi 0.000] {[9.30][8.39]}
[435.00 s] [108 C (227 F)] [hTotal 17.59] [Bi 0.000] {[9.24][8.35]}
[440.00 s] [107 C (224 F)] [hTotal 17.50] [Bi 0.000] {[9.18][8.32]}
[445.00 s] [106 C (222 F)] [hTotal 17.40] [Bi 0.000] {[9.12][8.29]}
[450.00 s] [104 C (219 F)] [hTotal 17.32] [Bi 0.000] {[9.06][8.25]}
[455.00 s] [103 C (217 F)] [hTotal 17.23] [Bi 0.000] {[9.00][8.22]}
[460.00 s] [102 C (215 F)] [hTotal 17.14] [Bi 0.000] {[8.95][8.19]}
[465.00 s] [100 C (212 F)] [hTotal 17.06] [Bi 0.000] {[8.90][8.16]}
[470.00 s] [99 C (210 F)] [hTotal 16.97] [Bi 0.000] {[8.85][8.13]}
[475.00 s] [98 C (208 F)] [hTotal 16.89] [Bi 0.000] {[8.80][8.10]}
[480.00 s] [97 C (206 F)] [hTotal 16.81] [Bi 0.000] {[8.75][8.07]}
[485.00 s] [96 C (204 F)] [hTotal 16.73] [Bi 0.000] {[8.70][8.03]}
[490.00 s] [94 C (202 F)] [hTotal 16.66] [Bi 0.000] {[8.65][8.00]}
[495.00 s] [93 C (200 F)] [hTotal 16.58] [Bi 0.000] {[8.61][7.97]}
[500.00 s] [92 C (198 F)] [hTotal 16.51] [Bi 0.000] {[8.56][7.94]}
[505.00 s] [91 C (196 F)] [hTotal 16.43] [Bi 0.000] {[8.52][7.91]}
[510.00 s] [90 C (194 F)] [hTotal 16.36] [Bi 0.000] {[8.48][7.88]}
[515.00 s] [89 C (192 F)] [hTotal 16.29] [Bi 0.000] {[8.44][7.85]}
[520.00 s] [88 C (190 F)] [hTotal 16.22] [Bi 0.000] {[8.40][7.82]}
[525.00 s] [87 C (189 F)] [hTotal 16.15] [Bi 0.000] {[8.36][7.79]}
[530.00 s] [86 C (187 F)] [hTotal 16.08] [Bi 0.000] {[8.32][7.76]}
[535.00 s] [85 C (185 F)] [hTotal 16.02] [Bi 0.000] {[8.28][7.74]}
[540.00 s] [84 C (183 F)] [hTotal 15.95] [Bi 0.000] {[8.25][7.71]}
[545.00 s] [83 C (182 F)] [hTotal 15.89] [Bi 0.000] {[8.21][7.68]}
[550.00 s] [83 C (180 F)] [hTotal 15.83] [Bi 0.000] {[8.18][7.65]}
[555.00 s] [82 C (179 F)] [hTotal 15.76] [Bi 0.000] {[8.14][7.62]}
[560.00 s] [81 C (177 F)] [hTotal 15.70] [Bi 0.000] {[8.11][7.59]}
[565.00 s] [80 C (176 F)] [hTotal 15.64] [Bi 0.000] {[8.08][7.57]}
[570.00 s] [79 C (174 F)] [hTotal 15.58] [Bi 0.000] {[8.05][7.54]}
[575.00 s] [78 C (173 F)] [hTotal 15.52] [Bi 0.000] {[8.01][7.51]}
[580.00 s] [78 C (171 F)] [hTotal 15.47] [Bi 0.000] {[7.98][7.48]}
[585.00 s] [77 C (170 F)] [hTotal 15.41] [Bi 0.000] {[7.95][7.45]}
[590.00 s] [76 C (169 F)] [hTotal 15.35] [Bi 0.000] {[7.93][7.43]}
[595.00 s] [75 C (167 F)] [hTotal 15.30] [Bi 0.000] {[7.90][7.40]}
[600.00 s] [75 C (166 F)] [hTotal 15.24] [Bi 0.000] {[7.87][7.37]}


A couple of things that I should mention regarding this output:

1) It is only an approximation. I simplified a lot of calculations and used a lot of interpolation from charts to get a rough idea of the temperature change of a piece.

2) The data I am using for steel is a combination of pure iron (heat capacity) and 1010 carbon steel (thermal conductivity) just because it's the only thing available to me. I think it gives a good enough picture of how much time we would have to do certain things.

3) I couldn't find data on the energy required for Ferrite to transform into Austenite so I assumed it was 0. From the graphs I saw in Verhoeven's book, there wasn't much of a change when the temperature exceeds the transformation point. Also, energy liberated from retransformation back to ferrite will occur below what this program was aiming to simulate.



Side note to all those interested in the data; I am looking into more controlled heat treatment techniques for higher hardenability steels such as O1 (pretty much only steel available to me locally). Assuming the temperature must drop below 1100 F in 7 seconds or less, a heat transfer coefficient at the surface must be between 400 and 3300 (W/m^2 K). 400 will barely drop the temperature below this point in around 7.5 seconds and above 3300, the temperature change at the surface is so drastic that the surface temperature will be significantly lower than the core temperature. (see Biot number explanation in previous post) This is for low alloy steels with a maximum thickness of 3/16 inch and width of around 1 1/2 inch. Thickness and surface area determine the minimum and maximum points.

Here are some interesting quench media that I looked into:

1) Forced air at 77 F at around 300 m/s will provide a coefficient of 350. Add in radiation of around 100 and it will barely do the job. If you could secure a blade in a wind tunnel (i.e. very small steel tube and blow it with a leaf blower, it would do the trick (volumetric flow rate - same volume of air through a smaller opening = faster speeds)). Note though that 300 m/s is approaching the sound barrier.

2) Liquid lead bismuth eutectic at 200 C gives a coefficient of around 3500. I was looking to see if it were possible and beneficial to first quench a blade into this and then take the whole container of this and further cool in oil or water. Technically, heat transfer is slowest between lead bismuth eutectic so this could be used to limit the quench speed. It's just expensive.

3) Liquid lead has a coefficient slightly higher than 3500. Only issue is that it would solidify at around 350 C.

4) Boiling water quench. The vapor jacket of water is terrible for quenching because it could be uneven and slow especially for lower hardenability steels however; I looked into the numbers and the coefficient of heat transfer in the film boiling range (total vapor jacket) is between 200 at around 300 C and 700 at around 800 C. Theoretically speaking, if you could quench in boiling water and pull it out right at around 350 C before the vapor jacket breaks, it could be a very controlled quench. There are plenty of videos on youtube where people drop red hot metal balls into water and that vapor jacket builds up very nicely and evenly.
 
The delay in cooling rate between stainless steel and aluminum may look like a big amount when comparing their thermal conductivity, but there is another part of the equation - mass. In either case, the amount of thermal mass in quench plates is so much more than the blade that the cooling will take nearly the same time. To delay the cooling rate, place an insulator between the plates and the blade. In my old days, it would be a sheet of asbestos paper. Nowadays, a piece of fiberglass cloth would work just as well.

If you want anti-warp clamps that will also delay the cooling curve significantly, glue two strips of Ins-board on the angle iron plates. This will keep the blade straight, and absorb virtually no heat at all. I may do this to mine, as it sounds like a good idea.
 
Last edited:
PEU said:
Thanks Duurza, i'm still a little confused about how to interpret the data.



I need to test this ASAP! great idea on the Fiberglass cloth.

Pablo
Click to expand...

Just look at the first 2 columns. If you take the piece out at 900 C, after 10 seconds, it would be around 768 C and after 20, around 713 C.

If you take it out at 815 C (close to 814 so use 5 seconds), subtract 5 seconds from the time. For example, after 10 seconds, it will be around 737 C (entry for 15 seconds).

The rest of the columns are only useful if you are interested in the science behind the heat loss. Since the loss is quite slow, there's nothing really interesting other than the fact that it's not *technically* air cooling (majority of loss is due to radiation which means that it would still cool nearly as fast in a vacuum).
 
Hey duurza, very interesting information. And useful too to see, for normalizing, how long you have to wait (approximately) in between cycles. Surprising how long it can take for something to cool down in air!

Just want to say that I tried the clamping method again last night on a wakizashi (21" long) using an I-beam and a piece of angle iron on top. 5160 steel. Clamped immediately after an interrupted quench, waited a few minutes, and it came out perfectly straight. I love this technique ;)) Especially considering how much warped blades irked me before!
 
nickandersonart said:
Hey duurza, very interesting information. And useful too to see, for normalizing, how long you have to wait (approximately) in between cycles.
Click to expand...
An easier signpost for knowing when to your steel is ready for the next normalizing cycle is when it becomes magnetic once again. It is actually the most fitting use of a magnet while heat treating.

The way I understand it...

Return to magnetic = New structure = Potential for new nucleation points.
 
nickandersonart said:
Hey duurza, very interesting information. And useful too to see, for normalizing, how long you have to wait (approximately) in between cycles. Surprising how long it can take for something to cool down in air!

Just want to say that I tried the clamping method again last night on a wakizashi (21" long) using an I-beam and a piece of angle iron on top. 5160 steel. Clamped immediately after an interrupted quench, waited a few minutes, and it came out perfectly straight. I love this technique ;)) Especially considering how much warped blades irked me before!
Click to expand...

I actually wrote this program to better understand why part of my O1 steel was nearly impossible to work on after forging. After I had forged it, I wrapped most of the piece with insulation but it wasn't large enough so a small area was exposed. I figured that air cooling was just too slow to harden it at all. Turns out I was correct! Unfortunately, heat loss via radiation was the most significant factor and the only way to avoid it is to reflect as much back at it.

If I have time, I'll do a bit of research and see if I can get some simulation going for plate quenching.
 
Rick Marchand said:
An easier signpost for knowing when to your steel is ready for the next normalizing cycle is when it becomes magnetic once again. It is actually the most fitting use of a magnet while heat treating.

The way I understand it...

Return to magnetic = New structure = Potential for new nucleation points.
Click to expand...

Hey Rick very interesting...so essentially you don't have to wait for the steel to cool in between normalization cycles? Would save me some time for sure :)


Sent from my iPad using Tapatalk
 
duurza said:
I actually wrote this program to better understand why part of my O1 steel was nearly impossible to work on after forging. After I had forged it, I wrapped most of the piece with insulation but it wasn't large enough so a small area was exposed. I figured that air cooling was just too slow to harden it at all. Turns out I was correct! Unfortunately, heat loss via radiation was the most significant factor and the only way to avoid it is to reflect as much back at it.

If I have time, I'll do a bit of research and see if I can get some simulation going for plate quenching.
Click to expand...

Yea O1 has certainly given me some troubles. Just found, after nearly completing and heat treating my first wakizashi made from O1 that it had small "crackles" or spiderweb-like cracks all over the surface. I tempered it and tested it by hacking a wooden board as hard as I could with no breakage or additional sign of stress, but I still gotta consider it a little bit spoiled :(

Not the most optimal choice for a small sword, I know...just wanted to try it with the O1 and see how it would hold up. Started over now with 5160.

Would be great to learn more about the extent to which O1 is hardening when it cools in air.

I think all this talk about O1 may be digressing a bit from the main topic...perhaps we should open a new thread about this and the cooling rates of the steels in air as well as plate quench etc., including all of the info from the program you wrote etc. it is super interesting after all and would be cool to get more into the specifics of it!




Sent from my iPad using Tapatalk
 
nickandersonart said:
Yea O1 has certainly given me some troubles. Just found, after nearly completing and heat treating my first wakizashi made from O1 that it had small "crackles" or spiderweb-like cracks all over the surface. I tempered it and tested it by hacking a wooden board as hard as I could with no breakage or additional sign of stress, but I still gotta consider it a little bit spoiled :(

Not the most optimal choice for a small sword, I know...just wanted to try it with the O1 and see how it would hold up. Started over now with 5160.

Would be great to learn more about the extent to which O1 is hardening when it cools in air.

I think all this talk about O1 may be digressing a bit from the main topic...perhaps we should open a new thread about this and the cooling rates of the steels in air as well as plate quench etc., including all of the info from the program you wrote etc. it is super interesting after all and would be cool to get more into the specifics of it!




Sent from my iPad using Tapatalk
Click to expand...


We could start a new thread on that.

Right now my gut feeling tells me that it's highly like that plate quenching can be used on its own to harden O1. I'll work on the data to prove/disprove my hypothesis though.
 
duurza,
It has been researched before, and the consensus was that it is right on the cusp of possibility.

If the austenitization temps are kept at the lower limit, thickness is on the thin side, and the aluminum quench plates are large mass .... it will harden.

Get too thick, too hot, or too little thermal mass for heat transfer, and it doesn't full harden.

My recommendation for anyplace wanting to experiment with plate quenching O-1 would be to do thin blades and profile only before HT. This will giver maximum contact for heat transfer in the plate quench.
 
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