C70S6材料连杆胀断掉屑原因分析及机理探究  

Cause analysis and mechanism study of fracture splitting drop-dregs of C70S6 material connecting rod

作　　者：孙军 倪培相 林栋 周扬帆 葛全慧 SUN Jun;NI Peixiang;LIN Dong;ZHOU Yangfan;GE Quanhui(Tianrun Industry Technology Co.,Ltd.,Weihai 264400,China)

机构地区：[1]天润工业技术股份有限公司,山东威海264400

出　　处：《冶金分析》2024年第6期94-100,共7页Metallurgical Analysis

摘　　要：利用火花放电原子发射光谱仪、金相显微镜、扫描电子显微电镜(SEM)、万能拉伸试验机等仪器,对C70S6材料连杆进行化学成分、金相组织、胀断面宏观及微观形貌、机械性能等检测分析,深入研究了连杆大头孔胀断掉屑的原因与机理。结果显示:胀断掉屑位置主要在毛坯分模面附近,掉屑连杆分模面处晶粒度为6.5级,铁素体含量(质量分数,下同)为7.0%,整个胀断面晶粒度级差为3.5级,脱落钢渣边缘为明显的韧性断裂特征。无掉屑连杆分模面处晶粒度为5级,铁素体含量为5.0%,胀断面晶粒度级差为0.5级,组织均匀性好,微观形貌呈脆性解理特征。综合分析得出,连杆毛坯组织不均匀,局部晶粒细小,整体级差大,致使毛坯材料局部塑性偏高,是导致胀断掉屑的根本原因。通过调整锻造连杆用棒材的生产及热处理工艺,粗化组织晶粒,降低晶粒度级差和铁素体含量,掉屑问题完全消除。The chemical composition,metallographic structure,macro and micro morphology of fracture splitting,and mechanical properties of C70S6 material connecting rod were detected and analyzed by spark discharge atomic emission spectrometer,metallographic microscope,scanning electron microscope(SEM)and universal tensile testing machine.The fracture splitting drop-dregs cause and mechanism of connecting rod big head hole were analyzed.The results showed that the fracture splitting drop-dregs position was mainly near billet parting plane,and the grain size at the parting plane of drop-dregs connecting rod was Grade 6.5.The content of ferrite was 7.0%(mass fraction,the same below),and the grain size difference of the whole fracture splitting surface was Grade 3.5.The edge of dropped steel slag showed obvious characteristics of ductile fracture.The grain size at the parting plane of no drop-dregs connecting rod was Grade 5,and the ferrite content was 5.0%.The grain size difference of fracture splitting surface was Grade 0.5,and the microstructure uniformity was good.The microstructure showed the characteristics of brittle cleavage.The comprehensive analysis showed that the microstructure of connecting rod billet was not uniform,the local grains were fine,and the overall grade difference was large,resulting in the high local plasticity of billet material,which was the root cause of the chip loss.By adjusting the production and heat treatment process of the bar for forging connecting rod,the grain size of microstructure was coarsened,the grain size difference and ferrite content was reduced.Consequently,the problem of drop-dregs loss was completely eliminated.

关 键 词：C70S6材料 胀断 掉屑 晶粒度 组织均匀性 

分 类 号：TG115.21[金属学及工艺—物理冶金] TG142.1[金属学及工艺—金属学]