摘要
为提高高速钢的综合性能,利用行星式球磨机将M2高速钢(W_(6)Mo_(5)Cr_(4)V_(2))粉体与纳米尺寸的Y_(2)O_(3)颗粒进行低能球磨混合,并采用激光选区熔化制备Y_(2)O_(3)弥散强化M2高速钢.实验结果表明,球磨后的M2高速钢粉体基本呈球形,未发生严重变形,表面嵌布大量纳米级Y_(2)O_(3)颗粒.激光选区熔化成形的Y_(2)O_(3)弥散强化M2高速钢试样的致密度为98.3%,纵向微观组织主要为等轴晶和柱状枝晶,横向微观组织为等轴晶,平均晶粒尺寸为900 nm.X射线衍射结果显示Y_(2)O_(3)颗粒的加入对M2高速钢物相种类影响不大,仍由马氏体相、残余奥氏体相和碳化物组成.其抗拉强度达到了943 MPa,与未添加Y_(2)O_(3)颗粒的高速钢相比,强度提高了36%.
M2 high speed steel(W_(6)Mo_(5)Cr_(4)V_(2))is an important engineering material,and with modern industry progressing,increased requirements are put forward for improved performance of high speed steel.To improve its comprehensive properties,M2 high speed steel powder is mixed with nano-sized Y_(2)O_(3) particles through mechanical alloying.This mixture is then used to create Y_(2)O_(3) dispersion strengthened M2 high speed steel by selective laser melting(SLM)electrometallurgy technology.The process parameters for SLM are as follows:laser power of 220 W,scanning speed of 800 mm·s-1,powder layer thickness of 0.03 mm,scanning spacing of 0.1 mm,and a substrate preheating temperature of 200℃.The effects of Y_(2)O_(3) particles on the microstructure and mechanical properties of the prepared high speed steel were investigated using various techniques,including optical microscopy,scanning electron microscopy,energy-dispersive X-ray spectroscopy,transmission electron microscopy,and mechanical property tests.Experimental results show that after low-energy ball milling,the M2 high speed steel powder remains mostly spherical with minimal deformation,preventing uneven spreading during the powder laying process.The surface of M2 high speed steel powder is coated with a large number of nanometersized Y_(2)O_(3) particles.The relative density of Y_(2)O_(3) dispersion strengthened samples formed by SLM is 98.3%.These samples exhibit a relatively smooth surface without obvious cracks,and the quality of the top surface quality is better than that of the side surfaces.The material’s basic structure and morphology are influenced by the molten pool and channel.Hexagonal honeycomb grains are evident in the molten channel,with fine grains distributed at the edges and slightly larger grains inside.The molten pool consists mainly of equiaxed crystals at the center and columnar dendrites at the boundaries,with grains growing epitaxially along the molten pool boundary.EDS(energy dispersive spectrometer)results show that elements Y and O are evenly distributed within the matrix,with no significant segregation.Subsequently,phase analysis reveals that adding Y_(2)O_(3) particles has little effect on the phase composition of M2 high speed steel,which remains mainly martensite,residual austenite,and carbides.Owing to the small amount of Y_(2)O_(3) added,no diffraction peaks of Y_(2)O_(3) were found in the detection range.TEM results show that Y_(2)O_(3) particles are larger at grain boundaries,reaching up to 90 nm,while smaller nanoparticles are diffusely distributed within the grains.Mechanical testing indicates that Y_(2)O_(3) dispersion strengthened high speed steel samples fabricated by SLM exhibit good mechanical properties,with tensile strength reaching 943 MPa,a 36% increase compared to M2 high speed steel without Y_(2)O_(3) particles.Its fracture surface is flat with a few cleavage steps and columnar crystals,indicating brittle fracture behavior.The addition of Y_(2)O_(3) particles produces a larger number of nucleation sites,refines grain size,and hinders dislocation movement,preventing crack propagation along grain boundaries,thereby enhancing the mechanical properties of M2 high speed steel.
作者
刘岩
赵定国
李月
崔小杰
王书桓
薛月凯
LIU Yan;ZHAO Dingguo;LI Yue;CUI Xiaojie;WANG Shuhuan;XUE Yuekai(School of Metallurgy and Energy,North China University of Science and Technology,Tangshan 063210,China)
出处
《工程科学学报》
EI
北大核心
2025年第1期33-43,共11页
Chinese Journal of Engineering
基金
国家自然科学基金资助项目(52074128)
中央引导地方科技发展资金资助项目(226Z1008G)。
关键词
激光选区熔化
M2高速钢
氧化物弥散强化
激光电冶金
力学性能
selective laser melting
M2 high speed steel
oxide dispersion strengthened
laser electrometallurgy
mechanical property
作者简介
通信作者:薛月凯,E-mail:gyyzhao@163.com。
