Low thermal expansion alloy
A low thermal expansion alloy having a high rigidity and a low thermal expansion coefficient comprising, by mass %, C: 0.040% or less, Si: 0.25% or less, Mn: 0.15 to 0.50%, Cr: 8.50 to 10.0%, Ni: 0 to 5.00%, and Co: 43.0 to 56.0%, S: 0 to 0.050%, and Se: 0 to 0.050% and having a balance of Fe and unavoidable impurities, the contents of Ni, Co, and Mn represented by [Ni], [Co], and [Mn] satisfying 55.7≤2.2[Ni]+[Co]+1.7[Mn]≤56.7 and the structure being an austenite single phase.
1. An alloy comprising, by mass %,
C: 0.040% or less,
Si: 0.25% or less,
Mn: 0.15 to 0.50%,
Cr: 8.50 to 10.0%,
Ni: 0 to 5.00%,
Co: 43.0 to 54.2%,
S: 0 to 0.050%,
Se: 0 to 0.050% and
a balance of Fe and unavoidable impurities,
contents of Ni, Co, and Mn represented by [Ni], [Co], and [Mn] satisfying
55.7≤2.2[Ni]+[Co]+1.7[Mn]≤56.7,
a structure of the alloy being an austenite single phase,
wherein
the alloy has a thermal expansion coefficient of −1.0×10 −6 /° C. to +1.0×10 −6 /° C.
2. The alloy according to claim 1 , wherein the alloy comprises 43.0 to 54.0% of Co, by mass %.
3. The alloy according to claim 1 , wherein the alloy comprises 43.0 to 52.0% of Co, by mass %.
4. A method for producing the alloy according to claim 1 , comprising the steps of:
heating an alloy to 700 to 1050° C., the alloy comprising:
C: 0.040% or less,
Si: 0.25% or less,
Mn: 0.15 to 0.50%,
Cr: 8.50 to 10.0%,
Ni: 0 to 5.00%,
Co: 43.0 to 54.2%,
S: 0 to 0.050%, and
Se: 0 to 0.050% and
having a balance of Fe and unavoidable impurities,
contents of Ni, Co, and Mn represented by [Ni], [Co], and [Mn] satisfying
55.7≤2.2[Ni]+[Co]+1.7[Mn]≤56.7;
cooling the alloy in a furnace.