材料期刊网

冷作强化非调质钢螺栓经时效处理可以稳定组织、提高强度、降低残余应力。采用热处理加热装置进行系列工艺试验研究时效规律，借助光学显微镜、扫描电镜、拉伸试验机等设备，分析时效工艺对材料组织及性能的影响。研究结果表明，提高时效温度和延长时效时间皆使硬度升高；适合生产的最佳时效工艺为250~300℃，2.5小时，时效工艺和表面处理工艺可以同时进行；柯氏气团、铁素体中亚晶的形成和弥散碳、氮化合物析出是时效强化的主要原因。

Aging treatment is performed for microalloyed steel for cold hardening bolt, which can stabilize its microstructure, enhance its strength and reduce its residual stress. A series of process tests are implemented for studying aging rules by means of heating device of heat treatment, and effects of aging processes on microstructures and properties for materials are analyzed by using optical microscope, scanning electron microscope and tensile tester and so on. The results show that hardness is increased by both raising temperature and delaying aging time, 250~300℃ and 2.5 hours are served as best aging processes to meet manufacture, moreover, aging processes and surface treatment technique may simultaneously be carried out. Additionally，sub-grain boundary，Cottrell atmosphere and dispersion Carbide -nitride are precipitated in the ferrite grain, which mainly results in aging strength. Key words: aging processes; deformation strengthening; bolt; microstructures; properties