含ボロンばね鋼TS50 B60に関する研究(I)
1956 年 42 巻 2 号 p. 105-110
詳細
1956 年 42 巻 2 号 p. 105-110
It is reported by American investigators that B-treated Cr steel TS50B60 showed very good results for leaf or coil spring material of trucks, tractors and passenger cars. But in our country there is few data about this steel, and so the authors studied the properties of TS50B60 in comparision with SUP 6 (Si-Mn steel), SAE 5160 (Mn-Cr steel) and SAE 6150 (Cr-V steel) as minutely as possible.
Results of the studies were as follows:
1) Non-metallic inclusions.
There was little difference between different steels and so the influence of B-addition was not found.
2) Transformation points.
High temperature order was as follows:
A1 point: SAE6150>SAE5160 SUP6>TS50B60
A3 point: SAE6150>SAE5160>TS50B60 SUP6
3) Hardenability.
D1, calculated from the measured Jominy curves, were 115mm for SAE6150, 100mm for SAE 5160, 97mm for TS50B60 and 53mm for SUP6. The fading phenomena of B were not seen. The results of dilatometric observation at quenching were as same as above.
4) Tendency of quenching cracks.
The residual stress of quenched specimen showed the transformation type for different steels and had good coincidence with the tendency of quenching cracks that is in next order, SAE6150>SAE5160>TS50B60>SUP6.
5) Grain growth characteristics.
Under 1O50°C there was no marked difference and above this temperature grain growth became eminent, but TS50B60 was the most stable.
6) Decarburization, scaling and surface roughness at heating.
Decarburization depth was greatest at SUP 6 and became smaller in the next order, SAE 6150>SAE5160>TS50B60, but the tendency of scaling showed the inverse order to above. Surface roughness was best at SUP 6 and worst at SAE5160.
