Key Takeaways & Executive Findings
- •• Critical tempering at 610 °C yields the best strength-ductility balance (PSE=23.6 GPa·%) in a novel cast multiphase stainless steel. • Reverted austenite stability, governed by Ms and γSFE, drives TRIP and TWIP effects, enhancing mechanical performance. • Higher tempering temperatures cause Cr segregation and Cr-depleted zones, degrading corrosion resistance. • Multiphase coordinated deformation improves strength-ductility, but corrosion initiates at chemically inhomogeneous phase boundaries.
Abstract
A novel cast stainless steel featuring a multiphase microstructure and a nominal composition of Fe-13.5Cr-2.6Si-6.9Ni-1.1Cu-1.1Mn-1.0Mo-0.35Al-0.025C (wt.%) was investigated. Following solution treatment at 1,050 °C and water quenching, the specimens were subjected to further tempering at 570 °C, 610 °C, and 650 °C to explore the effects of critical tempering on microstructure, mechanical properties, and corrosion resistance. Various characterization techniques were employed to examine the phase distribution within the microstructure, with particular attention given to the content and morphology of reverted austenite. Tensile and corrosion tests were carried out to evaluate the performance of the specimens. The results reveal that critical tempering significantly enhances the mechanical properties, with the specimen tempered at 610 °C achieving the highest product of strength and elongation (PSE=23.6 GPa·%), whereas corrosion resistance deteriorates with increasing tempering temperature. Calculations of the martensite start temperature (Ms) and stacking fault energy (γSFE) for the reversed austenite in different specimens indicate that the stability of reversed austenite strongly influences mechanical behavior through the TRIP and TWIP effects. However, tempering-induced Cr segregation at ferrite/martensite interfaces and the formation of Cr-depleted zones become more pronounced at higher tempering temperatures, leading to a degradation in corrosion resistance. Furthermore, multiphase coordinated deformation improves the strength-ductility balance, while corrosion tends to initiate at chemically inhomogeneous phase boundaries.
1. Introduction
With the growing demand for enhanced mechanical performance in steels and the challenge of overcoming the traditional strength-ductility trade-off, the construction of multiphase, multiscale, and metastable (M3) microstructures have become an increasingly popular strategy among researchers in recent years [1]. Compared with single-phase ferritic or austenitic stainless steels, duplex stainless steels exhibit superior strength and corrosion resistance. Additionally, martensitic precipitation-hardened stainless steels offer better comprehensive properties than conventional martensitic steels. Therefore, the development of multiphase stainless steels presents a promising research direction.
Several studies have demonstrated the potential of multiphase stainless steels. Tavares et al. [2, 3] reported a martensite-based triphase stainless steel containing 37% ferrite and 7.4% reverted austenite, achieving an ultimate tensile strength exceeding 800 MPa along with elongation over 20%. Liu et al. [4, 5] further increased the Ni content to approximately 5.5wt.% to enhance the austenite fraction, achieving elongations beyond 36%, and conducted detailed investigations into the corrosion and hydrogen embrittlement behaviors.
Building upon these advances, Wu et al. [6-8] developed a novel triphase stainless steel based on the PH13-8 martensitic precipitation-hardened system by introducing ferrite through high Si addition and forming reverted austenite via critical tempering after quenching. The resulting steel exhibited an ultimate tensile strength greater than 1,000 MPa and an elongation exceeding 15%. Silicon not only provides substantial solid solution strengthening but also synergizes with chromium to promote the formation of a stable oxide passive film on the steel surface, thus positively influencing both mechanical properties and corrosion resistance [9-11].
Loading authentic research manuscript (Pages 1–5)...
Jing-yu He, Guo-qiang Liu, Zi-xiang Wu, Hua-wei Zhang, Xiang Chen (2026). Effect of critical tempering on microstructure evolution, mechanical performance, and corrosion behavior of a cast multiphase stainless steel. China Foundry. https://doi.org/10.1007/s41230-026-5206-2
Research & Educational Purpose Only:The translations, structured abstracts, analytical annotations, and data reports provided by SinoTechIntel are intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoTechIntel claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is the optimal tempering temperature for this cast multiphase stainless steel?
The optimal tempering temperature is 610 °C, which yields the highest product of strength and elongation (PSE=23.6 GPa·%) due to enhanced stability of reverted austenite and TRIP/TWIP effects.
How does critical tempering affect the corrosion resistance of the steel?
Corrosion resistance deteriorates with increasing tempering temperature due to Cr segregation at ferrite/martensite interfaces and formation of Cr-depleted zones, which become more pronounced at higher temperatures.
What mechanisms contribute to the improved mechanical properties?
The improved mechanical properties are attributed to the TRIP (transformation-induced plasticity) and TWIP (twinning-induced plasticity) effects, which are influenced by the stability of reverted austenite, as quantified by martensite start temperature (Ms) and stacking fault energy (γSFE).
What is the nominal composition of the investigated steel?
The nominal composition is Fe-13.5Cr-2.6Si-6.9Ni-1.1Cu-1.1Mn-1.0Mo-0.35Al-0.025C (wt.%).
Where does corrosion typically initiate in this steel?
Corrosion tends to initiate at chemically inhomogeneous phase boundaries, such as ferrite/martensite interfaces where Cr-depleted zones form.
Related Technical Papers & Translations
Pull-out capacity and energy absorption of cable bolts under impact loading
This study investigates the performance of high-strength cable bolts under impact loading conditions representative of rock bursts in underground environments. Although widely used, the dynamic behaviour of these cable bolts has received limited experimental attention, and their effectiveness in seismically active zones remains a subject of ongoing debate. To address this gap, a reverse pull-out test machine integrated with a drop hammer rig was employed. Tests were conducted on 70-t SUMO bulbed and non-bulbed cable bolts with encapsulation lengths of 300 and 450 mm, subjected to an impact energy of 14.52 kJ. Results indicate that non-bulbed cables, despite showing lower initial peak loads (average 218 vs. 328 kN for bulbed cables at 300 mm encapsulation), demonstrated superior energy absorption (average 11.26 vs. 8.75 kJ) and displacement capacity (average 48.40 vs. 36.25 mm). Increasing the encapsulation length for bulbed cables led to a reduction in initial peak load but improved displacement and energy absorption. The dominant failure mechanism was debonding at the cable-grout interface, characterised by frictional sliding and cable rotation. These findings provide new insights into the energy dissipation mechanisms of cables and support the development of more resilient ground support systems for dynamically active conditions.
Effect of eutectic content on microstructure and mechanical properties of Al-Zn-Mg-Cu alloys
The 7xxx series aluminum alloys have emerged as a particularly promising class of lightweight structural materials. However, the inherent strength of these materials is primarily influenced by the content and type of alloying elements added during the manufacturing process, as well as casting defects. The present study investigated the effects of eutectics formed by solute atoms (Zn, Mg, and Cu), with equal mass ratios (Zn/Mg=2, Mg/Cu=3) but varying overall contents, on the liquid film thickness, crack propagation depth, and the mechanical properties of the Al-Zn-Mg-Cu alloy after heat treatment. The results from gravity casting indicate that the intergranular liquid film thickness increases with the increase of eutectic content. A thick intergranular liquid film in the casting can accommodate greater strain during grain contraction, thereby preventing liquid film rupture and subsequent hot tearing. Concurrently, during the solution treatment at 475 °C, the residual eutectic fraction in the Al-7Zn-3.5Mg-1.18Cu alloy diminishes from 9.1% at 10 h to 0.35% at 40 h. At 165 °C, the Al-6Zn-3.0Mg-1.0Cu alloy exhibits the optimal mechanical properties, with a peak aging tensile strength of 510 MPa and an elongation of 6.4%. The incorporation of lower concentrations of solute atoms (Zn, Mg, and Cu) serves to reduce the barrier to dislocation precipitation, thereby enhancing alloy plasticity. However, when the proportion of alloying elements exceeds the solubility limit of the α-Al matrix at specific heat treatment temperatures, coarse residual phases remain intergranular, thereby significantly impairing the mechanical properties of the alloy. This study provides a reference for the optimal addition level of the main strengthening elements in Al‑Zn‑Mg‑Cu alloys.
Achieving optimal strength-conductivity balance in cast Al-2.3Fe-Mg-Si alloys via Mg/Si ratio regulation
The Al-2.3Fe eutectic alloy is regarded as a promising substitute for Cu conductors in automotive motors owing to its excellent castability and low resistivity. However, its application is restricted by the mutually exclusive relationship between electrical conductivity and mechanical strength. The microstructure and mechanical properties of Al-2.3Fe alloy were modified through Mg/Si alloying combined with T6 heat treatment in this work, leading to the development of a high-performance cast Al-2.3Fe-Mg-Si alloy. In the Al-2.3Fe-0.40Mg-0.72Si (Mg/Si=0.56) alloy subjected to T6 treatment, an electrical conductivity of (52.5±0.6)% IACS is achieved, while the ultimate tensile strength is significantly enhanced to 309.5±5.6 MPa. The addition of Mg and Si brings about marked changes in the solidification process of the Al-2.3Fe alloy, resulting in considerable variations in both the morphology of the second phase and its phase constitution. The aging behavior of the alloy is governed by second phase and solid solubility. Through optimization of the Mg/Si ratio, the aging response can be effectively enhanced. At the ratio of Mg/Si=0.56, a balance is achieved between solid solubility and precipitation, while simultaneously minimizing the detrimental impact on electrical conductivity and reaching the best mechanical properties and electrical conductivity in peak-aged Al-2.3Fe-xMg-ySi alloy. This work providing valuable insights for developing advanced conductor materials.