摘要
为消除螺栓在热处理中产生的各种缺陷,缩短生产周期,使铆螺钢免热处理.采用热模拟试验机、实验室轧机和多工位冷镦机对铆螺钢轧制实验,铆螺钢原料和成品分别在拉力试验机和万能试验机上进行拉力试验,并对其组织进行了分析.结果表明,铆螺钢经过控轧控冷,获得具有多边形铁素体、细片状珠光体、粒状贝氏体、残余奥氏体和少量MA岛的多相组织.由于控轧控冷后的多相组织及TRIP效应,改善了螺栓的强韧性.铆螺钢因低的屈强比可以直接由热轧棒材冷镦成螺栓,螺栓无需最终热处理,产品的力学性能满足8.8级螺栓国家标准的相应要求.
To eliminate various heat treatment defects for high stength bolts and save time for the parts to travel back and forth from process to process, thermomechanical controlled processing was conducted by a thermomeehanical simulator, a laboratory hot rolling mill and a multistage cold former. Mechanical properties of the bar and the bolts were determined by tensile testing on an INSTRON 4206 machine and an 30t universal testing machine respectively, and microstructures of these steels were investigated. The results show that a muhiphase microstructure containing polygonal ferrite, dispersed pearlite, granular bainite and retained austenite is obtained by controlling rolling and cooling. Strength and ductility of the bolt are improved by the multiphase microstructure after controlled rolling and cooling and the TRIP effect. The cold forging steel can be directly used to fabricate bolts from hot rolled bar due to its low yield ratio, and mechanical properties of the fabricated bolts can meet the standard of class 8.8 bolts without heat treatment.
出处
《材料科学与工艺》
EI
CAS
CSCD
北大核心
2008年第6期861-864,共4页
Materials Science and Technology
基金
国家自然科学基金资助项目(50334010)
沈阳市应用基础研究项目(1071198-1-00)
关键词
铆螺钢
控轧控冷
高强度
低屈强比
多相组织
cold forging steel
controlled rolling and cooling
high strength
low yield ratio
muhiphase microstructures
