08-28-2018, 05:08 AM
TOOL STEEL HRC54 versus HRC62
Next, we tested two A2 tool steel blades, hardened at HRC54 vs HRC62, to compare response to steeling by hardness. A2 is a high carbon, high molybdenum tool steel. The A2 blade #7 has been hardened to HRC 54, while the A2 blade #11 to HRC 62.
![[Image: A2_blades_steeling.JPG]](http://knifegrinders.com.au/SET/A2_blades_steeling.JPG)
We already had baseline data rolling them without steeling in our previous research Effect of Hardness on Edge Retention
We sharpened the A2 blades at 15 dps, and rolled the same way as the knives above.
Controlled edge rolling on the BESS SET Structural Edge Tester was done by series of 5 cycles to the 50th cycle, and then from the 50th to 100th cycle by series of 10 cycles; overall each blade received 100 rolling cycles.
After each series of rolling, edge sharpness was measured, and the edge was steeled on the smooth (polished) steel by 4 heel-to-tip light passes alternating edge sides, and the sharpness measured again.
As per the plan, the edge was reset once after the 50th rolling cycle on the grooved fine-cut steel by 4 heel-to-tip firm strokes alternating edge sides, and finishing on the smooth steel with 1 heel-to-tip light pass each side. However, in the course of testing, the HRC54 A2 blade went nuts, and we gave it one more edge-resetting steeling on the grooved steel.
Link to raw data >>
Averaged data
![[Image: steeling_table4.png]](http://knifegrinders.com.au/SET/steeling_table4.png)
Results are pretty intriguing.
While the knives, even though of differing hardness from HRC55 to HRC58, show the same pattern in the edge sharpness response to steeling, the A2 tool steel response is very different to both the knives, and between the A2 blades.
The A2 HRC54 blade initially behaved similarly to the stainless steel knives, showing clear benefit from smooth steeling, but a single grooved steeling killed the edge, and it won’t recover.
The A2 HRC62 blade initially outperformed the knives, as expected, showing some benefit from smooth steeling, however with more steeling became just like them; the steeling lowered the A2 tool steel HRC62 edge retention to that of a mainstream stainless steel knife, especially when done with a grooved (abrasive) steel. Overall, systematic steeling is slightly detrimental to the edge.
The below graphs for HRC54 and HRC62 show the rolled edge response to smooth steeling as a blue line compared to the grey baseline; grooved abrasive steeling is shown by the red arrow.
![[Image: chart_steeling_A2_HRC54.png]](http://knifegrinders.com.au/SET/chart_steeling_A2_HRC54.png)
![[Image: chart_steeling_A2_HRC62.png]](http://knifegrinders.com.au/SET/chart_steeling_A2_HRC62.png)
Conclusion
We, just like many before us, read the Prof. Verhoeven’s supposition on steeling of blades hardened at or over HRC60 as a warning against using them in the environments where steeling is common:
“It also seems likely that the hardness of the blades might have a significant effect on
the occurrence of edge breakout during steeling. Hardness values above HRC = 60
would increase the occurrence of breakout above that found here, and values below 60
would decrease occurrence.”
This supposition has been confirmed by our experiments, and by what we’ve seen steeling is not recommended for tool steels hardened over HRC60, though smooth steeling may be beneficial for tool blades of a lesser hardness.
Next, we tested two A2 tool steel blades, hardened at HRC54 vs HRC62, to compare response to steeling by hardness. A2 is a high carbon, high molybdenum tool steel. The A2 blade #7 has been hardened to HRC 54, while the A2 blade #11 to HRC 62.
We already had baseline data rolling them without steeling in our previous research Effect of Hardness on Edge Retention
We sharpened the A2 blades at 15 dps, and rolled the same way as the knives above.
Controlled edge rolling on the BESS SET Structural Edge Tester was done by series of 5 cycles to the 50th cycle, and then from the 50th to 100th cycle by series of 10 cycles; overall each blade received 100 rolling cycles.
After each series of rolling, edge sharpness was measured, and the edge was steeled on the smooth (polished) steel by 4 heel-to-tip light passes alternating edge sides, and the sharpness measured again.
As per the plan, the edge was reset once after the 50th rolling cycle on the grooved fine-cut steel by 4 heel-to-tip firm strokes alternating edge sides, and finishing on the smooth steel with 1 heel-to-tip light pass each side. However, in the course of testing, the HRC54 A2 blade went nuts, and we gave it one more edge-resetting steeling on the grooved steel.
Link to raw data >>
Averaged data
Results are pretty intriguing.
While the knives, even though of differing hardness from HRC55 to HRC58, show the same pattern in the edge sharpness response to steeling, the A2 tool steel response is very different to both the knives, and between the A2 blades.
The A2 HRC54 blade initially behaved similarly to the stainless steel knives, showing clear benefit from smooth steeling, but a single grooved steeling killed the edge, and it won’t recover.
The A2 HRC62 blade initially outperformed the knives, as expected, showing some benefit from smooth steeling, however with more steeling became just like them; the steeling lowered the A2 tool steel HRC62 edge retention to that of a mainstream stainless steel knife, especially when done with a grooved (abrasive) steel. Overall, systematic steeling is slightly detrimental to the edge.
The below graphs for HRC54 and HRC62 show the rolled edge response to smooth steeling as a blue line compared to the grey baseline; grooved abrasive steeling is shown by the red arrow.
Conclusion
We, just like many before us, read the Prof. Verhoeven’s supposition on steeling of blades hardened at or over HRC60 as a warning against using them in the environments where steeling is common:
“It also seems likely that the hardness of the blades might have a significant effect on
the occurrence of edge breakout during steeling. Hardness values above HRC = 60
would increase the occurrence of breakout above that found here, and values below 60
would decrease occurrence.”
This supposition has been confirmed by our experiments, and by what we’ve seen steeling is not recommended for tool steels hardened over HRC60, though smooth steeling may be beneficial for tool blades of a lesser hardness.
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