Post-fire net section fracture behaviour and residual resistances of S700 high strength steel non-staggered bolted connections

Microstructurally-based multi-phase finite element analysis of bending in Advanced High Strength Steels (AHSS)

Use of interphase boundaries quantification as a means to analyze the microstructural distribution in heat treated complex-phase advanced high strength steels and their influence in void nucleation

Interface-dominated toughening mechanism in yttrium-modified Cr–Mo–V steel: Beyond grain refinement and inclusion modification

Effect of cerium addition on inclusion evolution, phase transformation and microstructure during solidification in Al-killed high-strength steel for construction machinery

Analysis of the weakest regions and microstructural features influencing impact toughness in Q690 high-strength steel welded joints

Performance and mechanism of a dual-functional Cr2O3 additive for reinforcement and corrosion protection of deep mine grouting anchor cables

A novel multi-scale mechanical model for fatigue expansion of corroded high-strength steel wires

Retained Austenite Stability in Third-Generation Advanced High-Strength Steels: Thermodynamic, Mechanical, and Kinetic Frameworks for Forming and Crash Performance

Semi-empirical stress-strain model of structural steels with simulated seawater corrosion damage

Strength enhancement through grain refinement in the AISI 304L stainless steel often leads to a notable reduction in ductility due to the suppression of the transformation-induced plasticity (TRIP) effect. Accordingly, the potential of Si addition for performance improvement of AISI 304L stainless steel through coupled metastability engineering and martensite strengthening was investigated. The 304L, 304L-Si3, and 304L-Si5 (at%) alloys with controlled stacking fault energy (SFE) were examined under different grain sizes. Tensile behavior, work-hardening response, phase transformation kinetics, and strengthening mechanisms were systematically investigated. The results revealed that Si addition effectively reduces SFE and promotes TRIP effect at fine grain sizes, resulting in superior work-hardening capability, enhanced ductility, and improved tensile toughness compared to the base 304L alloy. Notably, the 304L-Si3 alloy provided a more favorable strength-ductility balance (strength ∼1031 MPa and elongation ∼73 %), surpassing many advanced high-strength steels. Kinetic analysis demonstrated that the 304L-Si3 alloy with a fully austenitic initial structure provides optimized martensitic transformation kinetics, retaining the transformation to higher strains and thereby leading to higher uniform elongations. Furthermore, Si alloying increases the intrinsic strength of the α′-martensite phase, with estimated strength values of ∼1.56, ∼1.67, and ∼1.70 GPa for the 304L, 304L-Si3, and 304L-Si5 alloys, respectively.

Electrochemical and gravimetric evaluation of a Zn/water hyacinth leaf extract hybrid composite as a green inhibitor for high-strength steel in acidic environment

Rational design of doping strategy for stable α-Fe2O3 passive films of high-strength steel against hydrogen ingress

Seismic performance of UHPC-HSC composite hollow bridge piers reinforced with high-strength steel bars

Divergent mechanical responses driven by local microstructural evolution during low-temperature aging in advanced high-strength steels

Hot deformation behavior of a novel V–N microalloyed high-strength steel: Microstructure evolution, constitutive equation, and processing MAP

The effect of welding position on the mechanical properties of high-strength low-alloy steel weld metals was investigated with an emphasis on low-temperature impact toughness. Welding was performed in horizontal (2G) and vertical-up (3G) positions using two filler wires with different alloying element contents. For the lower-alloying-content weld metals, the higher heat input associated with the 3G position promoted the formation of grain boundary ferrite and Widmanst?tten ferrite, while acicular ferrite remained the dominant phase, resulting in a pronounced reduction in impact toughness. In contrast, for the higher-alloying-content weld metals, excessive bainite formation in the 2G position led to a significantly reduced impact toughness, whereas a refined acicular ferrite microstructure developed in the 3G welds, yielding the highest impact toughness.

This study examines the microstructural evolution and mechanical properties of medium-thickness DP980 advanced high-strength steel subjected to simulated welding thermal cycles. Gleeble simulations reproduced the thermal histories of coarse-grained (CG), fine-grained (FG), intercritical (IC), and subcritical heat-affected zone (SCHAZ) subregions. Microstructures were analyzed by scanning electron microscopy (SEM), and X-ray diffraction (XRD), while Vickers microhardness and Charpy impact tests were performed at room temperature and -40 ℃. Results showed that CGHAZ and FGHAZ developed polygonal prior-austenite grains and lath martensite, yielding higher hardness and toughness than the base metal. In contrast, ICHAZ contained a heterogeneous mixture of ferrite, martensite, retained austenite, and martensite-austenite (M-A) constituents, which led to significant toughness loss at both temperatures examined. The SCHAZ contained tempered martensite within ferrite and showed only moderate changes in impact energy. Although overall trends were similar, impact toughness decreased further at -40 ℃. These findings highlight the critical role of intercritical microstructures in governing toughness and emphasize the need to control welding parameters to suppress detrimental M-A formation in DP980 steel.

Softening in the heat-affected zone (HAZ) of high-strength pipeline welds compromises its service safety but the corresponding softening mechanism is not well-understood. Softening behavior in the HAZ of two X80 pipeline girth welds with different base metal microstructures, i.e., acicular ferrite (AF)-dominated (X80-AF) and granular bainite (GB)-dominated (X80-GB), were investigated through microhardness tests and detailed microstructure characterization. The results showed that softening in the HAZ of two girth welds primarily occurred in the fine-grained (FG) HAZ, while hardening was found in the coarse-grained (CG) HAZ. X80-AF showed higher softening resistance than X80-GB, with softening ratios of 3.44% vs. 12.46%, and softened zone widths of 2.1 mm vs. 3.9 mm, respectively. Due to its high dislocation density and refined interlocking structure, AF could effectively inhibit phase transformation and grain coarsening during reheating, which resulted in smaller grains and a lower fraction of polygonal ferrite (PF) in the FGHAZ (28%). In contrast, coarse GB was more prone to grain coarsening and hence engendered higher PF proportion (68%). Therefore, for the microstructural design of high-strength pipeline steels, increasing the proportion of refined AF is beneficial to the softening resistance and thereby elevates the service safety of pipelines.

Experimental and simulation study on high-speed impact of composite-structured metal projectiles on high-strength steel targets