As a newly developed gun barrel steel, the novel steel has shown excellent high-temperature strength, high resistance to wear and erosion, contributing to the superior ballistic life of gun barrels. As ballistic life increases, the fatigue life becomes essential for the safety and reliability of gun barrels. This paper presents a comparison of the low cycle fatigue (LCF) behaviors between a novel steel and 30SiMn2MoV steel at 700 °C. A strain-controlled fatigue test was carried out on the novel steel and 30SiMn2MoV steel in the strain range from 0.2 to 0.6%. The cyclic stress response behaviors of the novel steel and 30SiMn2MoV steel show cyclic softening behavior. In addition, the shape of the hysteresis rings of the novel steel and 30SiMn2MoV steel exhibit no-Masing model behavior. Energy–life relationships results show that the novel steel has higher fatigue resistance than the 30SiMn2MoV steel at 700 °C. The results of fatigue fracture analysis show that the failure mode of the 30SiMn2MoV steel is a mixed mode of intergranular fracture and transgranular fracture, while the failure mode of the novel steel is intergranular fracture. The cyclic softening of the two materials can be attributed to the lath structure with a high density of dislocations gradually transforms into low energy subcrystalline and cellular structures at 700 °C. The novel steel has a better fatigue life than the 30SiMn2MoV steel at 700 °C and different strain amplitudes, which is mainly related to the carbides and lath martensite in the materials.

The coagulation cascade triggered by the contact between blood and the surface of implantable/interventional devices can lead to thrombosis, severely compromising the long-term safety and efficacy of medical devices. As an alternative to systemic anticoagulants, surface anticoagulant modification technology can achieve safer hemocompatibility on the device surface, holding significant potential for clinical application. This article systematically elaborates on the latest research progress in the surface anticoagulant modification of blood-contacting materials. It analyzes and discusses the main strategies and their evolution, spanning from physically inert carbon-based coatings and heparin-based drug-functionalized surfaces to hydrophilic/hydrophobic dynamic physical barriers, biologically signaling regulatory coatings, and bio-integrative/regenerative endothelium-mimicking surfaces. The advantages and limitations of the respective methods are outlined, and the potential for synergistic application of multiple strategies is explored. A special emphasis is placed on current research hotspots regarding novel anticoagulant surface technologies, such as hydrogel coatings, liquid-infused surfaces, and 3D-printed endothelialization, aiming to provide insights and references for developing long-term, safe, and hemocompatible cardiovascular implantable devices.

In this paper, we investigated the effects of the matrix and precipitates in Cr-Ni-Mo-V rotor steel on its mechanical properties after water quenching and tempering (450–700 °C). The results indicate that the microstructure and mechanical properties of the steel can be significantly adjusted by changing the tempering temperature. An excellent combination of tensile strength (1028.608 MPa) and elongation (19%) was obtained upon tempering at 650 °C. This is attributed to the martensite lath with a high dislocation density, solid solution strengthening and the strengthening effect of spherical Mo₂C and VC particles. At a tempering temperature of 550 °C, the precipitation and development of rod-shaped Fe₃Mo₃C resulted in a considerable drop in strength. At 650 °C, the dissolution of Fe₃Mo₃C and dispersion precipitation of Mo₂C and VC led to a large rise in strength. At 700 °C, the coarsening of Mo₂C and VC, together with the recrystallization of the martensite lath, resulted in a loss in strength. Meanwhile, as the tempering temperature was increased from 450 °C to 700 °C, the tensile fracture characteristics of Cr-Ni-Mo-V rotor steel gradually changed from cleavage fractures to dimple fractures.