Scientia Sinica

Internal Friction (Q-!)

Internal Friction (Q-!)

SCIENTIA SINICA Vol, V_

Temperature (°C)

300 250 200 150 100 a) 25

0.013

0.011 | 0.009

0.007 } 0.005

0.003 OFS any, 2. Oe Cony,

0.001 | fe

16 isi 2.0 2.2 24 2.6 2.8 3.0 Be 300 250 200 150 100 50 25

0.005 | 0.003 }

0.001

1.6 1.8 2.0 DD, 2.4 2.6 2.8 3.0 3.2 3.4 1000/T —>

g. 1. Variation of internal friction with temperature of quench-hardened steel

containing 1.36% C, Curve I, measurements begin at room temperature after quenching from 950°C; curve II, measurements again taken from room temperature after the completion of curve I up to 220°C; curve II, internal friction peak obtained by subtracting curve II from curve I; curve IV, specimen refrigerated at —78°C after quenching from 950°C; curve V, measurements taken with lowering temperature from 175°C.

When internal friction measurements were taken by lowering the temper-

ature from 170°C, the originally observed 130°C peak disappeared completely as shown by curve V. As the temperature was again raised from room temperature, the internal friction values followed precisely along curve V.

The phenomenon described above is highly reproducible. When the

specimen of which the 130°C peak disappeared was again subjected to austenitizing and quenching treatments, the 130°C peak re-appeared as before.

a) Z

Effect of carbon content