Influence of zirconium on mechanical properties and phase transformation in low carbon steel

Abstract

The influence of zirconium on the mechanical properties and phase transformation was investigated in low carbon steel. First, the steels are subjected to a special thermomechanical regime, and the hot rolled plates were used to characterise the tensile properties and impact toughness. Second, the phase transformation behaviour of the steels with various Zr contents was evaluated by both dilatometry and metallography. Finally, to confirm the existence of Zr containing precipitates in the Zr added steels, transmission electron microscopy and energy dispersive spectroscopy were used. It was verified that plenty of fine spherical (Nb,Ti,Zr)C, which is identified to be nearly 10 nm, can be formed when the concentration of Zr is in the range of 0.015–0.030. The effects of zirconium on the phase transformation, including proeutectoid ferrite and pearlite transformation, and mechanical properties evolution were also identified and discussed.

Effect of Zr addition on toughness and microstructure of coarse grained heat affected zone in Al deoxidised low carbon steel

“…However, it can be cautiously but reasonably asserted that the prior austenite grain size could be refined especially for the Zr bearing steel with 80-100 kJ cm 21 heat input because no GBF and WF were detected in these samples. In fact, our previous research 11 has concluded that the primary austenite grain can be refined by 0.015% Zr addition, which can also be a further evidence for this speculation. As a consequence, the refinement microstructure in Zr added steel should be a major factor in enhancing the toughness because grain refinement strengthening can improve the toughness and tensile properties of the steel simultaneously.…”

“…12,13 The mechanical properties are as follows: yield strength 448 MPa (S1), 468 MPa (S2); tensile strength 545 MPa (S1), 566 MPa (S2); average transversal impact toughness (-40uC) 120 J (S1), 192 J (S2), which was reported in the previous paper. 11 Weld simulation was performed on a thermomechanical simulator to investigate impact toughness and microstructural evolution changes in CGHAZ among the two steels. Specimens were machined into the dimensions of 11|11|55 mm.…”

“…The present article is a successive study of the author's previous work. Our previous work 11 has focused on the influence of Zr addition on the phase transformation and precipitates to establish the relationship between Zr content and mechanical properties in Al deoxidised low carbon steel. In that work, it is demonstrated that the appropriate strength and impact toughness can be well balanced by adding 0.015% Zr into the steel through sulphide modification, ferrite promotion, grain refining strengthening and precipitation strengthening.…”

Effect of magnesium addition in low carbon steel part 2: toughness and microstructure of the simulated coarse-grained heat-affected zone

“…The ingots were then rolled into 13-mm plate using the thermo-mechanical control process (TMCP), with a cooling rate of 10°C s −1 and a final cooling temperature of 400°C. The finished temperature was 900°C, and the test steels were followed with a faster cooling rate of 10°C s −1 , The detail description of the process is given in our previous studies [6,7,26]. The mechanical properties are as follows: yield strength 448 MPa (S1), 473 MPa (S2); tensile strength 545 MPa (S1), 605 MPa (S2); elongation 33.6% (S1), 36.5% (S2); micro Vickers hardness 180 HV0.2(S1), 192 HV0.2(S3); and average transversal impact toughness (–20°C) 127 J (S1), 188J (S2), which was reported in the previous paper [6].…”

The Microstructure and Property of the Heat Affected zone in C-Mn Steel Treated by Rare Earth

“…It can meliorate the toughness of HAZ obviously without reducing the strength. Therefore, the steel toughness increases with the increasing of AF [6][7][8].…”