Investigation On Surface HSS Containing Ti Obtained By Double-Glow Plasma Alloying

By using the technique of Double-glow Plasma Surface Alloying (DGPSA) W , Mo and Ti are solute together into the surface of different carbon-content steels The alloying layer like the composition of High Speed Steel is formed on the surface of materials .There are three kinds of microstructure in the alloying layer which are alloying ferrite , alloying pearlite and white-light layer In the experiment , by analysing and studying the microstructure , the carbon-content of substrate , the thickness of the alloying layer in different processing parameter and different composition proportion of the source-electrode , the best processing parameters , carbon-content of the material and composition proportion of the source-electrode are found and some conclusions are reached that C(alloying element concentration) and Ld(alloying layer thickness) increase along with increasing of heat temperature , heat preservation time and source electrode voltage ; C and Ld have a A outline along with increasing of air-pressure and cathode voltage ; C and Ld decrease accompanied by increasing of substrate carbon-content; whatever processing parameters and steel III abstract type , micro-hardness of alloying layer is always higher than that of substrate parts . According to the ability of our experiment equipment and detection method ,the best processing parameters of the experiment as follows source electrode voltage ( Vs) I000V cathode voltage (Vc)400V ; atmospheric pressure (P)7OPa; distance of the two electrode(d)2Omm ; heating temperature(T) 11000C ; heat preservation time ( r ) 5h .The name of the sample , pure iron or 20 steel ; composition of source electrode Ti 30% , 50%( W,Mo are 50 percent of the rest ) and 100%. And then the workpiece is hardened and tempered , a kind of new type high speed steel 搒urface High Speed Steel containing Ti is formed .The results of the experiment show that the micro-structure of this new type surface high speed steel are composed of the tempering martensite in the alloying layer and even tiny grain-like carbide . By comparison with common high speed steel , the carbide is more uniform and smaller ; the second phases are M6C ( Fe3W3C ) . M7C3[ (FeWMo)7C3]and MC(TiC. y -M0C) carbide through the method of X-ray diffraction analysis ; the hardness of the alloying layer is 760?90 HV0 which is equal to 62~-69HRC ,and the hardness of core is 510 HV01 which is equal to 5OHRC ,this meets the needs of high hardness in the surface layer and the enough hardness good elasticity in the core of material .The high temperature hardness of the alloying layer is about 760HV01 which is equal to 62HRC . By comparison with common high speed steel , the hardness , wear- resisting ability and the high temperature hardness of it are higher...