摘要
采用直读光谱仪、数显洛氏硬度计、光学显微镜、扫描电子显微镜及能谱仪,对H13钢模具镶块断裂失效件的化学成分、表面硬度、断口形貌及显微组织进行检测和分析。结果表明,该模具镶块失效件断裂的原因是:锻造过程严重过热造成极粗大的组织晶粒,使材料强度显著降低;基体组织中低熔点夹杂物熔融的晶间熔洞,进一步降低材料的强度和韧性;沿粗大晶界析出碳化物及硫化物等脆性相,降低材料强度,增加材料晶间脆性;同时,晶界处回火不充分,组织应力显著增大,产生沿晶开裂的裂纹。这种低强度、高脆性的模具镶块,难以承受外加应力的作用,最终造成研配过程的轻敲断裂。
The chemical composition,surface hardness,fracture morphology and microstructure of the fracture failure part for H13 steel mold insert were detected and analyzed by direct reading spectrometer,digital Rockwell hardness tester,optical microscope,scanning electron microscope and energy dispersive spectrometer.The results show that the failure of mold insert is caused by the severe overheating in the forging process resulting in the extremely coarse grain of the structure,which significantly reduces the material strength.However, the intergranular melting holes of low-mehing point inclusions in the matrix structure further reduce the strength and toughness of material, and the such as carbides and sulfides and precipitate phases brittle along the coarse grain boundary which reduce material strength and increase intergranular brittleness.Simultaneously,tempering at the grain boundaries is not sufficient,and the tissue stress increases significantly to produce intergranular crack.Thus,the low-strength and high-brittle mold insert are difficult to withstand the external stress eventually resulting in tapping rupture in fitting process.
作者
郭联金
金林奎
欧海龙
方曼婷
彭铁坤
Guo Lianjin;Jin Linkui;Ou Hailong;Fang Manting;Peng Tiekun(Department of Electrical and Mechanical Engineering,Dongguan Polytechnic,Dongguan 523808,China;Guangdong Dongguan Quality Supervision Testing Center,Dongguan 523808,China;National Mold Product Quality Supervision and Inspection Center,Dongguan 523808,China)
出处
《锻压技术》
CAS
CSCD
北大核心
2018年第12期126-130,135,共6页
Forging & Stamping Technology
基金
2018年广东省大学生科技创新培育专项基金项目(pdjhb0902)
东莞职业技术学院2017年科研基金重点项目(2017a05)
关键词
H13钢
失效分析
过热组织
晶间熔洞
解理断口
二次裂纹
沿晶裂纹
H13 steel
failure analysis
overheating organization
intergranular molten hole
cleavage fracture
secondary crack
intergranular crack
