Effect of heat treatment on the mechanical properties and microstructure of HSLA steels processed by various technologies

Abstract

This study presents a striking advance in investigating the influence of heat treatment on the microstructure and properties of high strength low-alloyed steels obtained using various technologies. In contrast to the normalization treatment, the application of the thermo-mechanical control process (TMCP) offers higher strength characteristics but less stable properties during consequent high-temperature heat treatment. It has been established that the mechanical properties of both the steels are stable up to 650 °C. With an increase in the treatment temperature, the mechanical properties of the TMCP steel (grade S460M) are strongly degraded, while the normalized steel (grade S355J2) remains stable up to 950 °C. This is attributed to intensive grain growth at a temperature higher than Ac3 for TMCP steel and to the microstructural stability of the normalized steel. It is shown that the structural stability during high-temperature heat treatment is controlled by a number of factors such as heating temperature and holding time, grain growth, accumulated strain, the presence of deformation texture, steel deoxidation, and dissolution/uncontrolled growth of precipitations.

Effect of Tempering Temperature on Microstructure and Properties of a New Type of Nitrogen‐Containing Hot‐Work Die Steel 3Cr7Mo2NiSiVN

“…These undissolved precipitates on grain boundaries played an important role in Zener pinning prior austenite grain boundaries (PAGBs) and controlling grain growth during the austenitizing process in refs. [26][27][28] (Figure 4c). In addition, the prior austenite grain was divided into martensite package and martensite block after quenching.…”

“…It is well known that the strengthening mechanism includes grain refinement strengthening, solution strengthening, precipitation strengthening, and dislocation strengthening. [28,36,37] Because the austenitizing temperature was the same and the tempering temperature was lower than the recrystallization temperature, the prior austenite grain size would not be affected. Therefore, the grain refinement strengthening effect at different tempering temperatures can be considered to be equal.…”

Thermodynamic Analysis of Precipitation Process of Complex Carbonitride TixV1-xCyN1-y in HSLA-Type Steel

“…Metallic microadditions in the interaction with C and N form stable MX-type interstitial phases with a NaCl network, which makes it possible to manufacture steel products with a fi ne-grained structure, giving them high strength and guaranteed resistance to cracking. Such a technological solution ensures a signifi cant reduction in production costs as a result of the elimination of energy-consuming heat treatment operations or its limitation to tempering only [17][18][19].…”

Effect of Pulse Current GMAW on the Yield Stress of the S460M TMCP Steel Welded Joints

“…Quality requirements in many industries such as shipbuilding, civil engineering, hydropower, etc. dictate new rules for the development of welding technologies for metal structures while maintaining a high set of performance properties [1][2][3][4][5]. The addition of alloys in micro doses has the potential to be a key factor for higher strength [6,7].…”

“…Thus, the behavior of the metal under such thermal effect (welding thermal cycle) is crucial in the welded joints' mechanical properties formation, firstly due to structural transformation occurred. In this case, the mechanism of further structure evolution [4,11,12] is determined by a number of factors. During being in the temperature interval above critical points [13] Ac1, Ac3, the dispersion carbides (formed by doping elements) and carbonitrides of microalloying elements [14,15] reduce the tendency of the austenite to grow the grain size [16], either by blocking the migration of austenite grain boundaries (Zener pinning effect) [17].…”