Effect of Alloying Elements on the Drawability of Eutectoid Steel Wires

Abstract

We have reported the systematic research about the effects of alloy elements on the pearlite lemellar spacing (LPS) and the degree of regularity of pearlite (LPA) in the preceding paper. In this paper, the effects of alloy elements on the drawability and the strength and ductility of the wire with a pearlite lamellar structure are discussed.
It is well-known that the strength and ductility of the wire as drawn depend strongly on the wire diameter, but there are few researches on it. Therefore, we have studied the effect of alloy elements on the strength and ductility of fine wire under 0.5 mm as drawn chiefly. The main results are as follows.
(1) The maximum drawing strain (MDS) and the attained maximum strength (AMS) change linearly with the logarithm of diameter of wire as patented.
(2) MDS shows the maximum value in the condition of about 0.10 μm LPS. On the other hand, AMS increases as LPS decreases. In oredr to get higher MDS, it is important to control LPS in about 0.10 μm in patenting. Then, in order to get higher AMS, it is useful to make LPS as narrow as possible.
(3) As the carbon content increases, MDS decreases. On the other hand, AMS of the fine wire as drawn is not affected by the carbon contents of 0.71-0.94%C.
(4) The silicon makes the strength of the fine wire higher, but the effect depends on the drawing strain. So, we have to select the optimum addition according to the drawing strain.
(5) The manganese lowers the ductility of the fine wire as drawn.
(6) The alloy elements like chromium which makes LPS narrower are effective in increasing the strength of the fine wire.
(7) The alloy elements like cobalt which makes LPA larger are effective in improving the ductility of the fine wire as drawn.