Title

THE INFLUENCE OF Ni ON THE HOT DUCTILITY OF C-Mn-Al, Cu CONTAINING STEELS AS A WAY OF PREVENTING "HOT SHORTNESS"

THE INFLUENCE OF Ni ON THE HOT DUCTILITY OF C-Mn-Al, Cu CONTAINING STEELS AS A WAY OF PREVENTING "HOT SHORTNESS"

Authorship

MINTZ, B.; COMINELI, O.; KARJALAINEN, L. P.

MINTZ, B.

I am this author

COMINELI, O.

I am this author

KARJALAINEN, L. P.

I am this author

DOI

10.5151/2594-5327-3638

Downloads

Abstract

The increasing use of scrap in steel-making introduces copper into steels, resulting in an increasing incidence of hot cracking. The aim of the investigation has been to obtain a greater understanding of the role of Ni in preventing the hot cracking caused by copper. The influence of Ni on the hot ductility of C-Mn-Al, Cu containing steels has been investigated over the temperature range 800–1000 °C. A Gleeble machine was used to carry out the hot tensile tests. The as-cast tensile specimens were protected from oxidation by using an argon atmosphere. The fracture surfaces were examined with the SEM and the precipitates identified from carbon extraction replicas using the TEM. In samples cooled at a rate of 25 °C/min, preliminary results indicate that the addition of 0.3–0.5%Ni to a C-Mn-Al steel with 0.5%Cu results in some improvement in the hot ductility (measured by the reduction in area values). The results are discussed in the light of all the previous work on the subject and it is concluded that small Cu additions to steel cause the hot ductility to deteriorate and give a greater incidence of transverse cracking, not because of conventional “hot shortness” but because the copper can precipitate out as fine CuS inclusions. Ni additions prevent these sulphides from forming.

The increasing use of scrap in steel-making introduces copper into steels, resulting in an increasing incidence of hot cracking. The aim of the investigation has been to obtain a greater understanding of the role of Ni in preventing the hot cracking caused by copper. The influence of Ni on the hot ductility of C-Mn-Al, Cu containing steels has been investigated over the temperature range 800–1000 °C. A Gleeble machine was used to carry out the hot tensile tests. The as-cast tensile specimens were protected from oxidation by using an argon atmosphere. The fracture surfaces were examined with the SEM and the precipitates identified from carbon extraction replicas using the TEM. In samples cooled at a rate of 25 °C/min, preliminary results indicate that the addition of 0.3–0.5%Ni to a C-Mn-Al steel with 0.5%Cu results in some improvement in the hot ductility (measured by the reduction in area values). The results are discussed in the light of all the previous work on the subject and it is concluded that small Cu additions to steel cause the hot ductility to deteriorate and give a greater incidence of transverse cracking, not because of conventional “hot shortness” but because the copper can precipitate out as fine CuS inclusions. Ni additions prevent these sulphides from forming.

Keywords

hot ductility, nickel, hot shortness

hot ductility, nickel, hot shortness