Effect of C and Nb on Strength and Toughness of Al-killed Steels for Low Temperature Service
1982 Volume 68 Issue 16 Pages 2561-2568
Details
1982 Volume 68 Issue 16 Pages 2561-2568
The effect of C content of less than 0.04% and Nb addition on the mechanical properties of base metal and the toughness of weld bond was investigated on Al-killed steels for low temperature service.
The main results obtained are as follows:
(1) The toughness of base metal was the highest when C content was between 0.01 and 0.02%.
(2) The strength of Nb steel was not lowered significantly by decreasing the C content when it was less than 0.02%. This was attributed to the increase in hardenability due to solute Nb and the precipitation of Nb carbonitrides. The strength of Nb free steel, on the other hand, decreased with the decrease in C content.
(3) The toughness of weld bond of Nb steel was the highest when C content was between 0.01 and 0.02%. In the case of Nb free steel, on the other hand, the decrease in C content below 0.04% did not improve the toughness of weld bond. This was due to the fact that the grain grew as C content decreased in the case of Nb free steel, while the grain growth was restrained by solute Nb in the case of Nb steel.
(4) From these facts, C content between 0.01 and 0.02% and Nb addition were concluded to be the most appropriate for Al-killed steels for low temperature service.
