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<p>[QUOTE="Pete Apple, post: 3574613, member: 103982"]Rockwell C Scale: Preliminary Force = 98.07N (10 kgf) Total Force = 1471N (150kgf)</p><p>Rockwell B Scale: Preliminary Force = 98.07N (10 kgf) Total Force = 980.7N (100kgf)</p><p>Rockwell 15T Scale Preliminary Force = 29.42N (3 kgf) Total Force = 147.1N (15kgf)</p><p><br /></p><p><br /></p><p>Another type of Rockwell Test Mark which may be found on Lincoln cents is a raised bump. If there is an indentation on a die caused by a Rockwell Test, then it would be transferred to the coin as a bump during the strike. I think it is important to understand what appearance we might expect this bump to take.</p><p><br /></p><p>Steel for dies is supplied to the U S Mint by Latrobe Specialty Steel Company, a Division of Carpenter Technology. The steel alloys are Alloy 52100 for small diameter coins and Alloy L6 for quarter on up. They are sold in the spheroidized annealed condition to a maximum Rockwell C hardness and certified capability hardness to a minimum Rockwell C hardness level. Everything is in Rockwell C scale. This hardness range is approximately 33 to 58 Rockwell C hardness. </p><p><br /></p><p>Alloy 52100 is a deep hardening steel alloy used for aircraft bearings and other high stressed parts where good rolling contact fatigue strength is required at temperatures below 400⁰F. Its typical composition is 1.05% C, 0.35% Mn, 0.30% Sn, 1.50% Cr, and the balance Fe. (Latrobe, 52100)</p><p><br /></p><p>Alloy L6 is a versatile oil-hardening tool steel that is characterized by good toughness and is suitable for tools, dies and machine parts. Its relatively high nickel content gives it greater impact toughness. Its typical composition is 0.70 C, 0.60 Mn, 0.25 Si, 0.70 Cr, 1.40 Ni, and the balance Fe. (Latrobe, L6)</p><p><br /></p><p>The level of hardness of these steel alloys requires testing with the Rockwell C Scale. The requirements for using this scale with this level of hardness necessitate the use of a spheroconical diamond tipped indenter. This means that the resulting indentation will have a different conformation than the hemispherical shape.[/QUOTE]</p><p><br /></p>
[QUOTE="Pete Apple, post: 3574613, member: 103982"]Rockwell C Scale: Preliminary Force = 98.07N (10 kgf) Total Force = 1471N (150kgf) Rockwell B Scale: Preliminary Force = 98.07N (10 kgf) Total Force = 980.7N (100kgf) Rockwell 15T Scale Preliminary Force = 29.42N (3 kgf) Total Force = 147.1N (15kgf) Another type of Rockwell Test Mark which may be found on Lincoln cents is a raised bump. If there is an indentation on a die caused by a Rockwell Test, then it would be transferred to the coin as a bump during the strike. I think it is important to understand what appearance we might expect this bump to take. Steel for dies is supplied to the U S Mint by Latrobe Specialty Steel Company, a Division of Carpenter Technology. The steel alloys are Alloy 52100 for small diameter coins and Alloy L6 for quarter on up. They are sold in the spheroidized annealed condition to a maximum Rockwell C hardness and certified capability hardness to a minimum Rockwell C hardness level. Everything is in Rockwell C scale. This hardness range is approximately 33 to 58 Rockwell C hardness. Alloy 52100 is a deep hardening steel alloy used for aircraft bearings and other high stressed parts where good rolling contact fatigue strength is required at temperatures below 400⁰F. Its typical composition is 1.05% C, 0.35% Mn, 0.30% Sn, 1.50% Cr, and the balance Fe. (Latrobe, 52100) Alloy L6 is a versatile oil-hardening tool steel that is characterized by good toughness and is suitable for tools, dies and machine parts. Its relatively high nickel content gives it greater impact toughness. Its typical composition is 0.70 C, 0.60 Mn, 0.25 Si, 0.70 Cr, 1.40 Ni, and the balance Fe. (Latrobe, L6) The level of hardness of these steel alloys requires testing with the Rockwell C Scale. The requirements for using this scale with this level of hardness necessitate the use of a spheroconical diamond tipped indenter. This means that the resulting indentation will have a different conformation than the hemispherical shape.[/QUOTE]
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