Dynamic fracture toughness and crack propagation mechanism of a heterogeneous heterostructured material under combined strengthening mechanisms

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics Pub Date : 2024-09-21 DOI:10.1016/j.engfracmech.2024.110508

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Abstract

Developing fracture-resistant high-strength steels is an attractive prospect for various structural applications. In this work, a combination of carburizing heat treatment (CHT) and shot peening (SP) was used to develop combined strengthening (CS) mechanisms and to improve the mechanical strength and dynamic fracture toughness of 18CrNiMo7-6 alloy steel. Standard tensile tests and split Hopkinson pressure bar tests were conducted to investigate the strength and dynamic fracture toughness of the 18CrNiMo7-6 alloy steel. The crack initiation and propagation of samples were studied using scanning electron microscopy and transmission electron microscopy. Microstructure characterization and molecular dynamic simulations indicated that the excellent dynamic fracture toughness of the CS samples could be attributed to the grain refinement after strengthening and the formation of numerous slip bands at the crack tips, reducing the stress concentration at the crack tips. The Cr₂₃C₆ precipitates have a positive effect on the strength improvement of 18CrNiMo7-6 alloy steel. The results showed that this research can be used to guide the design of steels with high-strength and high-dynamic fracture toughness.

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组合强化机制下异质异质结构材料的动态断裂韧性和裂纹扩展机理

开发抗断裂高强度钢是各种结构应用的一个诱人前景。在这项工作中，采用渗碳热处理（CHT）和喷丸强化（SP）相结合的方法开发了组合强化（CS）机制，提高了 18CrNiMo7-6 合金钢的机械强度和动态断裂韧性。为研究 18CrNiMo7-6 合金钢的强度和动态断裂韧性，进行了标准拉伸试验和霍普金森压力棒分裂试验。使用扫描电子显微镜和透射电子显微镜对样品的裂纹萌发和扩展进行了研究。显微组织表征和分子动力学模拟表明，CS 样品之所以具有优异的动态断裂韧性，是因为强化后晶粒细化，并在裂纹尖端形成了大量滑移带，从而降低了裂纹尖端的应力集中。Cr23C6 沉淀对 18CrNiMo7-6 合金钢的强度提高有积极作用。研究结果表明，这项研究可用于指导设计具有高强度和高动态断裂韧性的钢材。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Engineering Fracture Mechanics 物理-力学

CiteScore

8.70

自引率

13.00%

发文量

606

审稿时长

74 days

期刊介绍： EFM covers a broad range of topics in fracture mechanics to be of interest and use to both researchers and practitioners. Contributions are welcome which address the fracture behavior of conventional engineering material systems as well as newly emerging material systems. Contributions on developments in the areas of mechanics and materials science strongly related to fracture mechanics are also welcome. Papers on fatigue are welcome if they treat the fatigue process using the methods of fracture mechanics.