抄録
In continuance to the lst report, (No. 2 of this Journa1, 1956, p. 105-110) the authors studied the statical and dynamical mechanical properties of four spring steels, using the same specimens as before. The results were as follows:
1) At quenching and tempering, AISI 6150 showed the greater resistanee to tempering than other steels. As to the toughness (elongation, reduction of area and Charpy impact value) at the same hardness, AISI 6150 was the greatest and other three steels showed little difference.
2) On the tensile test with notched specimen, AISI 6150 had the greater resistance to tempering and at BHN 400 TS50 B60 was the best.
3) On the impact test at low temperature, AISI 6150 and TS50 B60 were good, and they had no clear transition points.
4) As to the resistance to hot deformation, TS50 B60 was the least and AISI 6150 was the greatest.
5) Fatigue limits found by the Schenck's repeated bending tester were 55kg/mm2 for AISI 6150 and TS50 B6O, and 53kg/mm2 for AISI 5160 and SUP 6.
6) Using the Sawai's fatigue machine of resonance type, the authors examined the test pieces of TS50 B60 and SUP 6 with the real size and heat-treated surface. The results of TS50 B60 were better than SUP 6, because the former had very thinner decarburized layer of surface than the latter.
From the above points, TS50 B60 were found to be very good spring steel.
