【作者】 刘琼；

【导师】 王从曾； 苏学宽；

【作者基本信息】 北京工业大学 ， 材料学， 2002， 硕士

【摘要】 本实验采用双层辉光离子渗金属技术进行了含钛表面冶金高速钢的研制，并对其性能尤其是摩擦磨损特性进行了研究。 为获得含钛表面冶金高速钢，首先采用双辉渗金属技术，对不同含碳量的基体表面进行W、Mo、Ti三元共渗，以形成类似高速钢合金成分的等离子合金化层（渗层）。实验结果表明，渗层组织为合金铁素体，合金珠光体和白亮层；渗层的显微硬度总高于基体的显微硬度；渗层的厚度与合金元素浓度与工艺参数、源极成分配比、基体含碳量密切相关：合金元素浓度和渗层厚度随着源极电压Vs的提高而增加；随着阴极电压Vc的提高呈∧型，最佳值在400～500V间；随着气压p的提高也呈∧型，最佳值在40～70帕；随着极间距d的增大而减少，控制在15～20mm之间为最佳；随着工作温度T的升高而增加，随着基体含碳量的提高而迅速降低；增加源极成份配比中钛的比例，可以提高渗层中钛元素的浓度。本实验获得的最佳工艺参数为基材为低碳钢；源极成份配比为W:Mo:Ti=25％:25％:50％；Vs为1000V；Vc为400V；p为70帕；d为20mm；T为1100℃；t为5h。 然后，将渗层进行渗碳处理，以获得足够的合金碳化物。渗层经渗碳后，合金碳化物为M₃C（Fe₃C）、M₆C（Fe₃W₃C）、M₇C₃（Fe₇C₃）和MC（TiC、Y-MoC、WC）型碳化物；显微组织为粒状合金珠光体+不同形态（粒状、棒状）的合金碳化物，而且合金碳化物的分布与普通冶铸高速钢相比更为细小、弥散、均匀。 最后，对渗碳后的渗层进行淬、回火，以获得最终的含钛表面冶金高速钢。其合金碳化物为M₆C（Fe₃W₃C）、M₇C₃[（FeWMo）₇C₃]和MC（TiC、γ-MoC）型碳化物；显微组织为回火马氏体，其上分布着的均匀细小的粒状碳化物。其碳化物比普通冶铸高速钢细小均匀得多。 含钛表面冶金高速钢与普通冶铸高速钢相比，硬度、红硬性都有所提高，经淬、回火后的含钛表面冶金高速钢，硬度为760～890 HV0．1（相当于62～69HRC），心部硬度510 HV0．1（相当于50HRC）。红硬性为760HV0．1左右（相当于62HRC）。 北京工业大学硕士学位论文一 含钛表面治金高速钢的摩擦磨损特性为在干摩擦条件下主要表现为粘着磨损，其耐磨性随实验载荷及硬度的增大而增强；含钛表面冶金高速钢的碳化物的形状、大小及均匀性较好，有利于其耐磨性的提高；随着含钛量的提高含钛表面冶金高速钢的耐磨性明显增强，但因双辉渗过程中钛元素的渗入比较困难，其耐磨性受到影响，但源极成分配比含钛50％的表面冶金高速钢的耐磨性达到了普通高速钢的要求，并略高于普通高速钢。更多还原

【Abstract】 Metallurgical HSS on surface containing Ti (MHSSST) is obtained by Double-glow Plasma Surface Alloying (Xu-TEC), and its properties especially its wear behavior have been studied.The fist step to obtain MHSSST is to solute W Mo Ti into the surface of different carbon-content steels by Xu-TEC. The alloying layer is formed with three kinds of microstructure which are alloying ferrite, alloying pearlite and whiter-light layer, The mirco-hardness of the alloying layer is higher than that of matrix. The alloying layer thickness (Ld) and alloying element concentration (C) are affected by the processing parameter -, composition of the source electrode -, carbon-content of the matrix etc. The effects have been studied and concluded:With the increasing of source electrode Voltage (Vs) and heating temperature (T), heat preservation time (t), the Ld and C increase;With the increasing of carbon-content of matrix, the Ld and C decrease;Ld and C have a A outline with the increasing of air pressure(p) and cathode voltage (Vc).The best processing parameters have been concluded which are source electrode voltage(Vs)1000V; cathode voltage(Vc)400V; air pressure (p)70Pa; distance between Source electrode and cathode(d)20mm; heating temperature(T)1100 C; heat preservation time (t)5h; the material of matrix Low carbon steel; composition of source electrode Ti50% 25%W, 25%Mo.The second step for the MHSSST is carburizing the alloying layer for adequate alloying carbides. After carburizing, the microstructure is the grain-like alloying pearlitewith alloying carbides in different shapes. By method of X-ray diffraction analysis, The alloying carbides are M3C(Fe3C) M6C(Fe3W3C) M7C3(Fe7C3) and MC(TiC -MoC WC) carbides.Finally, MHSSST is formed by quenching and tempering the workpieces. the microstructure of the MHSSST is tempering martensite in the alloying layer with tiny grain-like alloying carbides which are M6C(Fe3W3C)> M7C3[(FeWMo)7C3]> and MC(TiC\ -MoC), the alloying carbides is smaller and more uniform.Comparing with common HSS , the properties (hardness > red hardness) of the MHSSST are higher . The hardness of the alloying layer of the MHSSST is 760?890HV0.1 equaling 62?9HRC; the hardness of core is 510HV0.1, equaling 50HRC; the red hardness of the alloying layer is 760HV0.1,equaling 62HRC.Wear behavior of the MHSSST has been studied:Adhesive wear is the main wear behavior of the MHSSST;With the increasing of the power, the wear resistance increases;With the increasing of hardness of the alloying layer, the wear resistance increases;The alloying carbides of the MHSSST are tiny> granular ?uniform, which is good for the wear resistance .With the increasing of Ti concentration, the wear resistance of MHSSST increases rapidly, Because it is difficult to solute Ti into the matrix by Xu-TEC, The wear resistance of MHSSST is limited, but the MHSSST with 50%Ti in the composition of source electrode has good wear behavior, which has met the needs of wear resistance of the common HSS or even a little higher.更多还原