Scientia Sinica

24 SCIENTIA SINICA Vol, V.

Temperature (°C) : 240 220 200 180 160 140 120 100 80 70 60 50

0.007

0.006

0.005

0.004

0.003

Internal Friction (Q-!)

0.002

0.001 1.9 2.0 ZL 222) 2.3 22: 2 ON e227, 2.8 2.9 3.0 oa!

1000/7 —> Fig. 3. Internal friction in 0.52 % C specimen after different heat treatments. Curve I, quenched from 910°C; curve II, quenched from 720°C; curve III, furnace-cooled from 910°C.

A similar specimen was quenched from 720°C into cold water during which a pearlitic structure was also obtained. No 130°C peak was observed in this case as shown by curve II.

(3) 0.29% C.—The effects of the rate and the temperature of quenching are shown by the following experiments.

When a 0.29% carbon specimen was quenched from 950°C into 10%

Temperature (°C)

180 160 140 120 100 80 60 40 20 0.006 = 0.005 0.004

0.003

Internal Friction (Q-!)

22 2:3 2:4 255. 2:6 257 228. 2:9 310 3a) 392) 3:3" 34 35

1000/T —> Fig. 4. Internal friction in 0.299% C specimen after different heat treatments. Curve I, quenched into 10% brine from 950°C; curve II, quenched into 10% brine from 700°C; curve III, quenched into oil from 950°C.