Aging of a copper bearing HSLA-100 steel

Abstract

Investigations were carried out on aging of a HSLA-100 steel after varying amounts of cold deformation. Mechanical properties (hardness, tensile properties and toughness) were measured and structural changes were studied using optical, TEM and SEM techniques. As a result of various treatments, the hardness and UTS could be significantly improved, but with drastic fall in ductility and impact strength, especially in peak aged conditions. The parameters affecting impact strength were examined and it was concluded that various microstructural features affected toughness through their influence on tensile properties. In this steel the impact strength could be improved by lowering the UTS and increasing the ductility (pct elongation). The improvement in hardness and UTS was attributed to formation of thick precipitate-dislocation tangles. The aging process caused a slow transformation of lath martensite into acicular ferrite due to occurrence of in situ recrystallization. The concentration of Cu in particles precipitating on aging was followed using EDAX technique.

Influence of Cu on Microstructure and Mechanical Properties for an Extremely Low Carbon Steel During Isothermal Process

“…Cu addition in steels can significantly improve the strength by virtue of nano‐sized Cu precipitates, and it can also affect the low temperature toughness. Panwar et al proposed that coherent Cu precipitates (bcc Cu structure) could cause rapid nucleation and growth of cracks, leading to a deterioration of toughness. The low temperature toughness can be improved by Cu precipitates with larger size, because the crack propagation can be effectively prevented by larger ones.…”

Effect of microalloying on aging of a Cu-bearing HSLA-100 (GPT) steel

“…This study shows that presence of Ti changes the complete precipitation behaviour of Cu-bearing HSLA steels. In our earlier publications (Panwar et al 2003(Panwar et al , 2005, results were reported on the effect of cold work on the precipitation behaviour of a Cu (1⋅58 pct) bearing HSLA-100 (GPP) steel, which contained Nb (0⋅03 pct) but no V and Ti. On aging, Cu rich precipitates were observed in the GPP steel.…”

“…Several attempts have been made to improve the yield strength and toughness of this structural material by the addition of alloying elements, special heat treatments as well as by thermomechanical treatments along with suitable modifications in production methods. Since Cu is added to HSLA steels to cause precipitation strengthening, Cubearing HSLA steels have attracted attention of researchers in the recent past (Dhua et al 2001a(Dhua et al , b, 2003Gomez et al 2002;Ghosh et al 2003Ghosh et al , 2004Ghosh et al , 2005Panwar et al 2003Panwar et al , 2005Bhagat et al 2004;Mao et al 2004). The design philosophy underlying such steels is to reduce the C content to ~ 0⋅05 wt pct, to improve weldability and to increase toughness via the precipitation hardening effects associated with high (1-2 pct) Cu contents.…”

3001 Published By: Blue Eyes Intelligence Engineering & Sciences Publication Retrieval Number: B8113129219/2019©BEIESP DOI: 10.35940/ijitee.B8113.129219 Journal Website: www.ijitee.org Age Hardening in COR-Ten Steel

“…It is also attributed to nucleation and growth of the precipitate particles as the aging progresses. Accordingly, the dip and rise in the hardness curve as a function of aging time were obtained grains [16][17][18][19].…”