Browse Topic: Steel
A machine-learning strategy has generated a new class of ultra-high strength and ductility steel for 3D printing that costs less, resists rust, and requires only a fraction of the usual processing time.
To address the detection and monitoring needs of fatigue damage in ferromagnetic materials, this paper proposes a nondestructive testing method based on the evolution of magnetic hysteresis characteristics. By constructing a hysteresis loop measurement system, the variation patterns of coercivity (Hc) in Q235 steel specimens under cyclic loading were investigated, revealing three-phase characteristics of fatigue damage: the initial linear growth phase (N ≤ 8,000), the rapid rise phase (8,000 < N ≤ 12,000), and the stable oscillation phase (N > 12,000). Experimental results demonstrate that the relationship between coercivity and damage degree (D) can effectively characterize the processes of crack initiation, propagation, and instability, with significant inflection points observed at D = 0.6 and D = 0.8. The quantitative model based on coercivity provides a novel method for early warning and condition assessment of fatigue damage, offering advantages such as non-contact operation and high sensitivity. This study provides theoretical foundations and technical support for the health monitoring of engineering structures.
This specification, in conjunction with the general requirements for steel heat treatment covered in AMS2759, establishes the requirements for heat treatment of precipitation-hardening corrosion-resistant, maraging, and secondary hardening steel parts. Parts are defined in AMS2759. Parts made from steels other than those specified in this specification may be heat treated in accordance with the applicable requirements herein using processing temperatures, times, and other parameters recommended by the material producer unless otherwise specified by the cognizant engineering organization. General ordering instructions are specified in AMS2759.
This specification, in conjunction with the general requirements for steel heat treatment covered in AMS2759, establishes the requirements and procedures for three classes of gas, vacuum, liquid, and low-pressure carburizing (LPC) and related heat treatment of parts fabricated from carburizing-grade steels. Parts made from steels other than those specified in the detail specifications may be heat treated in accordance with the applicable requirements using processing temperatures, times, and other parameters recommended by the material producer. This specification does not cover pack carburizing.
With new energy vehicles developing rapidly, battery safety, as an important part of the impact on the range of new energy vehicles and vehicle safety, has become the focus of attention. The battery pack protection plate is a core component to protect the battery, its performance needs not only impact resistance, but also lightweight, honeycomb sandwich structure with its excellent energy absorption characteristics and weight reduction performance by the battery pack protection plate performance research. At present, the core-to-face sheet interaction in conventional sandwich structures subjected to impact loads has not been fully elucidated, and the quantitative characterization of damage is insufficient, so this paper aims to optimize the lightweight impact-resistant structure by exploring the synergistic energy dissipation mechanism between the high-strength core material and the steel plate. The study combines theory and simulation, adopting ideal rigid-plastic film theory to establish a critical response model to predict the structural failure threshold, equivalent single-layer theory to simplify the analysis of plywood, and a stiffness matrix model to quantify the structural mechanical contribution of each layer. A two-material synergistic design framework is proposed by fully considering the material properties and adopting the corresponding intrinsic structure and failure criteria for different materials. Analysis reveals that geometric confinement is a key characteristic of the honeycomb sandwich panel’s response and a strain gradient driving mechanism at low impact resistance, and a new energy distribution paradigm is found through the analysis of the energy absorption ratio. The theoretical and simulation results are in great agreement with each other, which just has a difference of 0.7% in the peak force, 1.4% in the critical displacement error, and less than 2% in the impulse integration error. The proposed dual-material co-design framework provides a solution for electric vehicle battery protection systems that balances lightweight and impact resistance.
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