附板折弯开裂的原因及预防措施  

Cause of Cracking of Attached Plates during Bending and Precaution

作　　者：陈立鹏 尚召华 王绪珍 金强光 CHEN Lipeng;SHANG Zhaohua;WANG Xuzhen;JIN Qiangguang(Qingdao Choho Industrial Co.,Ltd.,Qingdao,266705,Shandong China;Qingdao key laboratory of chain transmission,Qingdao 266705,Shandong China)

机构地区：[1]青岛征和工业股份有限公司,山东青岛266705 [2]青岛市链传动重点实验室,山东青岛266705

出　　处：《热处理》2024年第5期54-56,59,共4页Heat Treatment

摘　　要：农机链用40Mn钢附板通过折弯成形。一批直附板在冲压成形和去应力退火后折弯至90°时开裂。为揭示附板折弯开裂的原因,对开裂的附板和原材料进行了宏观分析、化学成分分析、硬度检测和金相检验;复查了去应力退火工艺;对直附板进行了调质处理而不再进行去应力退火。结果表明:附板的原组织为铁素体、球状珠光体和少量片状珠光体,符合要求;去应力退火后附板组织为铁素体和片状珠光体,塑性较差,从而折弯成形时开裂;直附板的片状珠光体是去应力退火温度升高到了800℃所致;调质处理的直附板组织为回火索氏体,塑性良好,折弯成形时没有开裂。The 40 Mn steel attached plate for agricultural machinery chain is to be formed by bending.A batch of direct attached plate cracked at the time of being bent to 90°after stamping and stress relieving.To reveal the reason why the attached plates cracked during bending,the cracked attached plate and the raw material were subjected to macro-analysis,chemical composition analysis,hardness measurements and metallographic examination.The reinspection of stress relieving process was performed.The direct attached plate was quenched and high-temperature tempered and was stress relieved no longer.The results showed that(a)the prior structure of the attached plate consisted of ferrite,spheroidal pearlite and a small amount of lamellar pearlite which conformed with the requirement;(b)the attached plate after stress relieving exhibited microstructure consisting of ferrite and lamellar pearlite whose plasticity was poor,thus cracked during bending forming;(c)the lemellar pearlite in the direct attached plate stemmed from a rise to 800℃in stress relieving temoperature;and(d)after quenching and high-temperature tempering the direct attached plate exhibited microstructure consisting of tempered sorbites thereby had good plasticity,did not cracked during bending forming.

关 键 词：去应力退火 调质 球状珠光体 折弯 

分 类 号：TG157[金属学及工艺—热处理]