摘要
SWRCH35K盘条生产高强度螺栓过程中表面出现横裂纹,通过低倍、高倍金相检验,分析组织特征,查找表面出现横裂纹的原因。结果表明,钢丝进行球化退火时温度偏高,会导致钢丝表层脱碳和边部部分晶粒长大,在适宜的冷却速度下,容易在钢丝边部形成粗大的魏氏组织;较软的表层魏氏组织和较硬的基体组织在钢丝横断面上分为内外两层,拉拔、冷镦时不同的组织将发生不协调变形,表层较软的魏氏组织最先出现微细裂纹,随着进一步的变形,微细裂纹在垂直于受力方向上扩展,遇到较硬的基体组织后停止扩展,最终导致表面横裂纹的产生。
Transverse crack occurred in surface while high strength bolt was produced by using SWRCH35K wire rod. Structure characteristic was analyzed through low magnification and high magnification examination to find the cause of transverse crack in surface. Results show that the temperature is higher when steel wire is spheroidizing anneal, which cau- ses steel wire surface decarburization and some side grain growth. Coarse widmanstatten structure occurs in steel wire side in proper cooling speed. Soft surface widmanstatten structure and hard matrix structure divide steel wire into two layers in cross section, different structure occurs different deformation in process of drawing and cold heading. Surface soft widma- nstatten structure occurs micro cracks firstly, with further deformation, micro cracks expand in direction of vertical force, and stop expanding after it is meet hard matrix structure, which cause occurrence of surface transverse crack finally.
出处
《金属制品》
2012年第1期50-52,56,共4页
Metal Products
关键词
SWRCH35K盘条
螺栓
冷镦
横裂纹
魏氏组织
球化退火
SWRCH35K wire rod
bolt
cold heading
transverse crack
widmanstatten structure
spheroidizing anneal
