Preparation Of Carbide Tools With Additives And Its Research On The Cutting Properties Of Stainless Steel

Stainless steel is a kind of material that is highly resistant to corrosion.Therefore stainless steel parts and components have been widely applied in the field of food,chemical engineering,medical treatment,etc.Generally,stainless steel parts and components are processed by hard alloy tool in order to improve their accuracy and quality.On one hand,stainless steel reflects typical work hardening due to its high ductility and toughness;on the other hand,this material leads to severe wear of tool and shorten its life due to low thermal conductivity,strong adhesion to tool material and serious adhesion of tool.A contrast test was conducted in this paper to determine the optimum ball milling period and sintering temperature of fine-grained WC+10%Co+X（property-modifying additive）hard alloy prepared by powder metallurgic method in order to prolong the service life of tool.The influence of additives Cr₃C₂,TaC,Re and Ru on hard alloy texture and performance was studied.Four hard alloy tools with different components were prepared and underwent dry-cutting austenitic stainless-steel test.The cutting performance of tool was also acquired.The research conclusions are as follows:1.For fine-grained hard alloy WC+10%Co+0.5%Cr₃C₂+1%TaC+0.5%Ru,the components of mixture are in the best dispersion uniformity,WC grains are refined and transverse fracture strength reaches the peak when ball grinding period is 60 h.The 36h ball grinding period is too short to distribute the raw materials of aggregate in mixture evenly.The additive fails to inhibit grain sintering and growth,the aggregated particles become faulty and reduce the transverse fracture strength of alloy;however,the 72h ball grinding period is too long,which leads to aggregation of bonding phase in alloy under the effect of cold welding,causing fracture defect and reducing alloy strength.2.Once sintered at 1,390°C,the fine-grained hard alloy WC+10%Co+0.5%Cr₃C₂+1%TaC+0.5%Ru reaches a density of 99.84%,hardness of 91.8 HRA and bending strength of3,354 MPa.When sintering temperature rises to 1,450°C,the alloy density will rise to 99.98%,but hardness drops to 91.7 HRA;bending strength firstly increases,then decreases and reaches the peak 3,962 MPa at 1,410°C.A higher sintering temperature leads to larger WC grain and lower coercive force.3.Once added with 0.5%Cr₃C₂+1%TaC additive in the fine-grained hard alloy WC+10%Co,the alloy grain size and the number of thick and big WC drop,harness and bending strength increase,and fracture toughness becomes lower.By adding 0.5%Cr₃C₂+1%TaC+1%Re or 0.5%Cr₃C₂+1%TaC+0.5%Ru,the hard alloy has higher fracture toughness on the basis of high hardness and strength.For alloy that contains WC+10%Co+0.5%Cr₃C₂+1%TaC+0.5%Ru,the hardness is 91.8 HRA,TRS is 3,962 MPa,fracture toughness is14.7 MN/m^3/2,and the comprehensive mechanical property is the best.4.According to the dry-cutting austenitic stainless-steel test,in comparison to the hard alloy containing no additive,hard alloy that contains different mixture combinations of Cr₃C₂,TaC,Re and Ru has better wear resistance and is less worn at front/rear side of tool.In particular,the tool containing WC+10%Co+0.5%Cr₃C₂+1%TaC+0.5%Ru enjoys the highest wear resistance,and the rear side wear is reduced by 39%.