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分享:ADC12铝合金压铸缸体硬质点分析及改进措施

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浏览:- 发布日期:2020-11-23 10:18:11【

印小松,刘宏庆,柯 研,康忠(zhong)臣

(重庆(qing)(qing)秦安铸造有(you)限公司,重庆(qing)(qing) 402247)

摘 要:某厂生(sheng)产(chan)的(de)一(yi)批 ADC12铝合(he)(he)金(jin)压铸缸(gang)体出现(xian)(xian)硬质点,在机加工(gong)时出现(xian)(xian)打刀现(xian)(xian)象(xiang),并(bing)使产(chan)品形成微裂纹.通过硬度检测、化(hua)学(xue)成分分析、金(jin)相检验、扫描电镜(jing)分析和(he)能(neng)谱分析等方法,对ADC12铝合(he)(he)金(jin)压铸缸(gang)体出现(xian)(xian)硬质点的(de)原因进行了(le)分析.结果表(biao)明:由于氮气纯(chun)度较(jiao)低、铝液不纯(chun)净、未及时扒渣,造成杂质进入铝合(he)(he)金(jin)压铸型腔后(hou)(hou)形成硬质点,从而(er)在机加工(gong)时出现(xian)(xian)打刀现(xian)(xian)象(xiang).最(zui)后(hou)(hou)提出了(le)相应的(de)改进措施

关键词:ADC12铝(lv)合金;硬质点;压铸缸(gang)体

中图分(fen)类号:TG146.1 文献(xian)标(biao)志(zhi)码(ma):B 文章(zhang)编号:1001G4012(2018)05G0339G04

汽(qi)车(che)发(fa)动(dong)机缸(gang)体(ti)(ti)(ti)以前多采(cai)用(yong)传(chuan)统灰铸(zhu)铁材料(liao)砂型铸(zhu)造,具有(you)缸(gang)体(ti)(ti)(ti)质(zhi)量(liang)大(da)、制造过(guo)程(cheng)对(dui)环境污染大(da)等缺点(dian).用(yong)铝(lv)合(he)金(jin)(jin)替(ti)代钢铁,符合(he)汽(qi)车(che)轻量(liang)化要求(qiu),可(ke)使汽(qi)车(che)零件质(zhi)量(liang)减轻65%[1].某厂结合(he)国际(ji)和国内现(xian)(xian)有(you)的条(tiao)件和经验,建成(cheng)了多条(tiao)先进(jin)的缸(gang)体(ti)(ti)(ti)压(ya)铸(zhu)生产(chan)(chan)线,主体(ti)(ti)(ti)材料(liao)为 ADC12铝(lv)合(he)金(jin)(jin),批(pi)(pi)量(liang)生产(chan)(chan)了多种规(gui)格的压(ya)铸(zhu)缸(gang)体(ti)(ti)(ti).具体(ti)(ti)(ti)生产(chan)(chan)工艺为:熔炼(lian)(配料(liao)→加精炼(lian)剂(ji)(ji)(ji)(ji)、覆盖剂(ji)(ji)(ji)(ji)、通氮(dan)气(qi)(qi)除(chu)气(qi)(qi)除(chu)杂→倒入转运包(bao)→加精炼(lian)剂(ji)(ji)(ji)(ji)、覆盖剂(ji)(ji)(ji)(ji)、通氮(dan)气(qi)(qi)除(chu)气(qi)(qi)除(chu)杂→保(bao)温(wen)炉)→保(bao)温(wen)炉保(bao)温(wen)→模(mo)具安装→开(kai)(kai)模(mo)→喷离型剂(ji)(ji)(ji)(ji)吹气(qi)(qi)→合(he)模(mo)→压(ya)铸(zhu)→开(kai)(kai)模(mo)→取件.正常的铝(lv)合(he)金(jin)(jin)压(ya)铸(zhu)缸(gang)体(ti)(ti)(ti)由于其(qi)本身的硬(ying)度普遍较低,机加工时一般不发(fa)生打刀(dao)现(xian)(xian)象(xiang).但(dan)最近生产(chan)(chan)的一批(pi)(pi)压(ya)铸(zhu)缸(gang)体(ti)(ti)(ti)出现(xian)(xian)很多硬(ying)质(zhi)点(dian),在(zai)机加时发(fa)生打刀(dao)现(xian)(xian)象(xiang),并使产(chan)(chan)品形成(cheng)微(wei)裂(lie)纹(wen).为了分(fen)(fen)析(xi)该批(pi)(pi)铝(lv)合(he)金(jin)(jin)压(ya)铸(zhu)缸(gang)体(ti)(ti)(ti)硬(ying)质(zhi)点(dian)产(chan)(chan)生的原因,笔(bi)者采(cai)用(yong)硬(ying)度检测(ce)、化学成(cheng)分(fen)(fen)分(fen)(fen)析(xi)、金(jin)(jin)相(xiang)检验、扫描电镜分(fen)(fen)析(xi)等方法对(dui)其(qi)进(jin)行了检验和分(fen)(fen)析(xi),并提(ti)出了相(xiang)应的预防改进(jin)措施.

1 理(li)化检(jian)验(yan)

1.1 硬度测试

在(zai) ADC12铝 合 金 压 铸 缸(gang) 体 出 现 打 刀(dao) 的 部 位(wei)(含微裂(lie)纹)取硬(ying)度(du)(du)试样(yang),采(cai)用(yong)维氏硬(ying)度(du)(du)计进(jin)行检测(ce),结果表明试样(yang)局部硬(ying)度(du)(du)达160~180HV,远高于(yu)缸(gang)体的硬(ying)度(du)(du)要求(qiu)70~120HV.

1.2 化学(xue)成分分析

采用直读光谱(pu)仪对缸体微裂纹附近区域(yu)进行(xing)化学(xue)成(cheng)分分析(xi),结果见(jian)表1,可见(jian)该(gai)压铸缸体的化学(xue)成(cheng) 分符合日本工(gong)业标准JISH5302:2006技术要求(qiu).

1.3 金相检验

    分(fen)(fen)别在(zai)缸体未(wei)出现硬质(zhi)点(dian)(dian)、出现硬质(zhi)点(dian)(dian)及微(wei)裂纹处制(zhi)取金相(xiang)(xiang)试(shi)样,经砂纸打磨、抛光后,用0.5%(体积分(fen)(fen)数)氢氟酸水溶液(ye)侵(qin)蚀,采用奥林巴斯 GXG51金相(xiang)(xiang)显(xian)(xian)微(wei)镜观察试(shi)样的(de)显(xian)(xian)微(wei)组(zu)(zu)织(zhi),如图1所示(shi).可见(jian)正常区域(yu)的(de)显(xian)(xian)微(wei)组(zu)(zu)织(zhi)为铝硅亚共(gong)晶(jing)组(zu)(zu)织(zhi),其中细小(xiao)的(de)黑(hei)色夹杂相(xiang)(xiang)在(zai)基体上均匀(yun)分(fen)(fen)布;异常区域(yu)的(de)黑(hei)色夹杂聚集呈大块或大条状分(fen)(fen)布.

1.4 扫描电镜和(he)能谱分析(xi)

取(qu)缸体裂纹区(qu)域,将裂纹打开,制(zhi)取(qu)扫(sao)描(miao)电镜试样,采(cai)用 TESCAN VEGA3LMH 扫(sao)描(miao)电镜(SEM)进行微观形貌分(fen)析和微区(qu)成(cheng)分(fen)分(fen)析,用扫(sao)描(miao)电镜在试样不同位置(zhi)选(xuan)取(qu)具(ju)有(you)代表性的 A,B,C,D 视(shi)场,各视(shi)场的 SEM 形貌如图2所示,其(qi)微区(qu)化学(xue)成(cheng)分(fen)

    见表(biao)(biao)(biao)(biao)2.图2a)中(zhong)(zhong)(zhong)(zhong)(zhong)(zhong) SEM 形貌显(xian)(xian)示显(xian)(xian)微(wei)组(zu)(zu)织(zhi)(zhi)(zhi)呈多孔(kong)(kong) 状,结(jie)合表(biao)(biao)(biao)(biao)2中(zhong)(zhong)(zhong)(zhong)(zhong)(zhong)的(de)(de)化学(xue)成(cheng)(cheng)分(fen)可(ke)(ke)知组(zu)(zu)织(zhi)(zhi)(zhi)中(zhong)(zhong)(zhong)(zhong)(zhong)(zhong)含有(you) Al2O3 (多孔(kong)(kong))夹(jia)杂相;图2b)中(zhong)(zhong)(zhong)(zhong)(zhong)(zhong)显(xian)(xian)微(wei)组(zu)(zu)织(zhi)(zhi)(zhi)存在大量(liang)的(de)(de)光(guang)滑 面,含有(you)许多白(bai)(bai)色夹(jia)杂物,结(jie)合表(biao)(biao)(biao)(biao)2中(zhong)(zhong)(zhong)(zhong)(zhong)(zhong)的(de)(de)化学(xue)成(cheng)(cheng)可(ke)(ke)知 组(zu)(zu)织(zhi)(zhi)(zhi)中(zhong)(zhong)(zhong)(zhong)(zhong)(zhong) 含 有(you) Al2O3 (无(wu) 孔(kong)(kong)),AlSiMnFe,硅 酸(suan) 铝(lv)(lv) 和(he) Al3C4 夹(jia)杂组(zu)(zu);图2c)中(zhong)(zhong)(zhong)(zhong)(zhong)(zhong)显(xian)(xian)微(wei)组(zu)(zu)织(zhi)(zhi)(zhi)有(you)灰色近球(qiu)形颗粒 物和(he)白(bai)(bai)色夹(jia)杂,结(jie)合表(biao)(biao)(biao)(biao)2中(zhong)(zhong)(zhong)(zhong)(zhong)(zhong)的(de)(de)化学(xue)成(cheng)(cheng)分(fen)可(ke)(ke)知颗粒物 为 Al2Cu,其 显(xian)(xian) 微(wei) 组(zu)(zu) 织(zhi)(zhi)(zhi) 中(zhong)(zhong)(zhong)(zhong)(zhong)(zhong) 也 含 有(you) Al2O3 (无(wu) 孔(kong)(kong) ), Al3C4 和(he) MgO??Al2O3 夹(jia)杂相;图2d)中(zhong)(zhong)(zhong)(zhong)(zhong)(zhong)显(xian)(xian)微(wei)组(zu)(zu)织(zhi)(zhi)(zhi)表(biao)(biao)(biao)(biao) 面粗糙(cao)呈灰白(bai)(bai)色,结(jie)合表(biao)(biao)(biao)(biao)2中(zhong)(zhong)(zhong)(zhong)(zhong)(zhong)的(de)(de)化学(xue)成(cheng)(cheng)分(fen),可(ke)(ke)知组(zu)(zu)织(zhi)(zhi)(zhi) 中(zhong)(zhong)(zhong)(zhong)(zhong)(zhong)含有(you) AlN,Al2O3(无(wu)孔(kong)(kong))和(he) MgO??Al2O3 夹(jia)杂物. 通过图2和(he)表(biao)(biao)(biao)(biao)2可(ke)(ke)知硬(ying)质(zhi)点夹(jia)杂相包(bao)含 Al2O3(多 孔(kong)(kong)或无(wu)孔(kong)(kong)),硅酸(suan)铝(lv)(lv),MgO??Al2O3,AlSiMnFe,AlN, Al3C4 等夹(jia)杂相