新型塑料模具钢的热处理特点和工艺参数选择

概述了我国近年来塑料模具材料研制与应用的进展,并对我国塑料模具材料今后的发展提出了一些建议.详细介绍了40CrMnMo7和40CrMnNiMo8.6.4 2种新型塑料模具钢调质热处理工艺的特性,讨论了不同尺寸塑料模具的选材及调质工艺参数选择等问题.     

Insights into plastic deformation mechanisms of austenitic steels by coupling generalized stacking fault energy and semi-discrete variational Peierls-Nabarro model

The generalized stacking fault energy (GSFE) is a key parameter to determine the plastic deformation mechanisms of austenitic steels. However, the underlying physics why the GSFE can affect the plastic deformation behaviors remains unclear. In this paper, the plastic deformation mechanisms of austenitic steels with different carbon (C) additions were investigated by coupling the GSFE with the semi-discrete variational Peierls-Nabarro (P–N) model. The internal mechanisms behind the P–N stress and plastic deformation were explained at atomic scale. It is found that the positions and contents of C atoms affect the GSFE of austenite, and thus regulate plastic deformation behaviors of austenitic steels by influencing dislocation core structure. As exemplified that with 4 ​at.%C in austenite, the intrinsic stacking fault energy increases from −433 to −264 mJ/m², and the stacking fault width increases to 6.62b from 4.72b of FCC-Fe with b being the Burgers vector. This corresponds to the plastic deformation mechanism dominated by the ε martensitic transformation with the lattice changing from FCC to HCP. With increasing C contents to 8 ​at.%, the intrinsic stacking fault energy of austenite increases to −9.01 mJ/m², while the stacking fault width decreases to 6.03b. The plastic deformation tends to proceed via the mechanical twinning mode. The present investigation establishes a solid foundation for clarifying the plastic deformation mechanisms of austenitic steels from the perspective of the dislocation core structure.     

Green economy and waste management: An inevitable plan for materials science

Covid is giving us many lessons among which one must be to realize that this is the time to act for sustainable future. The smart world around us has made it inevitable to have an alarming situation regarding the uncontrolled growth of waste products such as plastic and electronic wastes. Both are immense threats to the health of human, wildlife and environment, that eventually affect the societal and economic structures as evident from recent Covid-crisis. The proper management of these wastes and innovating ideas for new sustainable technologies are the need of the hour. Circular economy act with green technology (green economy) is the way to tackle this challenge. Current perspective presents the overview of the scenario regarding these burgeoning issues and demonstrates some measures that are taken or being considered to depend on to come out of them.     

浅谈中国插花创作特点

本文从构思立意、构图造型及命名三个方面阐述了中国插花的创作特点。中国插花艺术受中国传统文化的影响,采用师法自然并高于自然的手法,利用自然花材的姿质来体现作品的美,色彩上注重疏淡雅致,并注重作品的主题表达和诗情画意。作品形态自然、线条优美、意境隽逸、情趣盎然、耐人寻味。     

热辐射应力图像分析确定应力强度因子K_I 和裂纹尖端塑性区

本文借助于热辐射应力图像分析技术对裂纹尖端附近的应力场进行分析测定。记录了铝质紧凑拉伸试件的热辐射应力图像,给出裂纹尖端前沿的温度变化曲线。根据热弹效应和线弹性断裂力学理论,通过解析建立用热辐射应力图像分析技术确定Ⅰ型裂纹应力强度因子的基本方程。在此基础上,用热辐射应力图像分析技术实验确定Ⅰ型裂纹应力强度因子和裂尖塑性区。