NiCr-Cr_3C_2/Ni60B等离子喷焊层的组织与性能

Microstructure and properties of plasma surfaced Ni Cr-Cr_3C_2/ Ni60B layers

采用光学显微镜、X射线衍射仪(XRD)和显微硬度计等研究了Ni Cr-Cr3C2添加量、喷焊层数对H13钢表面Ni60B等离子喷焊层显微组织与性能的影响。研究表明:随着Ni Cr-Cr3C2添加量增加,喷焊层硬质颗粒相明显增多,组织更加细密和均匀。当添加10%Ni Cr-Cr3C2时,其显微硬度可达基材的4倍以上;喷焊层数增加,喷焊层出现明显的分层现象,且组织也变得不均匀,显微硬度下降;熔合区白色胞状晶粒为部分熔化的残留基材晶粒,柱状树枝晶区为联生结晶和以基材残晶为核心的"包覆结晶"共同作用的结果,与现有研究结果不同;喷焊层主相均为Cr2Ni3、(Ni,Fe)、Fe Ni3、(Fe,C)、Cr23C6,硬质强化相Cr2Ni3、Cr23C6、B2Fe3Ni3、Fe23B等显著提高了喷焊层的力学性能。

With optical microscopy,X-ray diffraction( XRD) and microhardness tester,the effects of Ni Cr-Cr3C2 and surfaced layers on microstructure and properties of plasma surfaced layer( Ni60B) on H13 steel were studied. The results show that the hard particulate phase in surfaced layer increases significantly and the microstructure is finer and distributes uniformly with the increase of Ni Cr-Cr3C2 content. When adding 10% Ni Cr-Cr3C2,its microhardness( HV) is more than four times of its substrate. The surfaced layers appear obvious stratification with the layers increasing. More layers can led to more complex stratification,more uneven microstructure and lower microhardness. The white cellular grains in fusion zone are grain core of partially melted substrate. Columnar dendrite area can result from epitaxial solidification and'coated crystallization'. The main phase in surfaced layer include Cr2Ni3、( Ni,Fe) 、Fe Ni3、( Fe,C) and Cr23C6 phases. The presence of the hard phases,such as Cr23C6,Cr2Ni3,Cr23C6,B2Fe3Ni3,and Fe23 B etc,can improve the mechanical properties of surfaced layer significantly.