Ni对新型压铸模具钢连续冷却转变规律的影响  

Effect of Ni on continuous cooling transformation characteristic of new type die-casting steels

作　　者：何雪松[1] 左鹏鹏[1] 吴晓春[1] 

机构地区：[1]上海大学材料科学与工程学院,上海200072

出　　处：《材料热处理学报》2015年第10期134-140,共7页Transactions of Materials and Heat Treatment

基　　金：国家自然科学基金(51171104)

摘　　要：采用热膨胀仪测定了含2.0%Ni和不含Ni的新型压铸模具钢SDYZ的连续冷却转变曲线（CCT曲线）,并结合金相法、扫描电镜（SEM）和维氏硬度分析了Ni元素对SDYZ钢连续转变规律、组织以及硬度的影响。结果表明,Ni元素可显著降低SDYZ钢的相变点（Ac1、Ac3和Ms）,扩大奥氏体相区,使CCT曲线右移;同时,Ni元素可使SDYZ钢获得全马氏体的冷速由0.3℃/s降低到0.1℃/s,提高钢的淬透性;但由于Ni是强奥氏体稳定化元素,会增加淬火残留奥氏体,从而使含Ni的SDYZ钢硬度降低了20~30 HV。Continuous cooling transformation（ CCT） diagrams of SDYZ die-casting steels with 2. 0% Ni and without Ni were measured by dilatometer. The effect of Ni on CCT diagram,microstructure and hardness of SDYZ steels was studied by means of optical microscope,scanning electron microscopy（ SEM） and Vickers hardness test. The results show that phase transformation temperature points（ Ac1、Ac3and Ms） of the SDYZ steels deceases significantly,austenite phase region expands,and CCT diagram moves to the right due to the addition of Ni. Meanwhile,the critical cooling rate of matensite drops from 0. 3 ℃ / s to 0. 1 ℃ / s because of Ni addition in the SDYZ steels. However,the hardness is reduced by 20-30 HV in the SDYZ steel containing Ni because Ni is strongly austenite stabilizing element and increases the amount of retained austenite.

关 键 词：压铸模具钢 Ni元素 CCT曲线 淬透性 

分 类 号：TG151.2[金属学及工艺—热处理]