High Toughness Tbm Cutter Ring Steel And Heat Treatment Process Of High Temperature Deformation Behavior Research

Due to the TBM cutter ring will bear seriously impact and sharply frictionin the process of broking hard rock, the number of disc cutter ring consumptionis huge and it’s service time has been the key factor related with the workingefficiency and cost of TBM project. Some famous TBM manufacturingcorporations abroad have formed advanced technology in producing disc cutterring whose products performed good comprehensive mechanical properties, butthe price is higher due to the blockade on techniques. Recently, some domesticcutter ring have been used in the TBM construction, and it’ mechanicalproperties is high hardness and low toughness. Based on the information fromthe construction site, the import disc cutter ring will perform well in the servicetime than the domestic disc cutter ring when working in the hard rock conditionsuch as granite. In addition, the domestic manufacturers usually improve disccutter ring’s mechanical properties through increasing alloying elements whichhave increased the consumption of resource. It has become one of the mostsophisticated problems needed to be solved urgently to upgrade the TBM disccutter ring steel in the energy conservation and emissions reduction way.In this paper, we started from low cost and high property, aims atimproving the comprehensive mechanical properties (high hardness and hightoughness) of designed steel. The alloying elements of TBM disc cutter ring hasbeen designed, and the high temperature deformation behavior and heattreatment process have been studied systematically. The concrete researchcontents and results have been listed below:(1) It is the principles of energy conservation、environmental protection andsustainable development. Based on the alloying elements of quenching andtempering steel(40CrNiMo), the steel for TBM disc cutter ring was designed byadding appropriate Ni and V. The results show that the designed steel has brokenthrough the traditional thinking restraint which usually improving the steelmechanical properties by adding alloying elements, and the experimental steelcan perform well properties with high hardness and high toughness. (2) The high temperature flow behavior of experimental steel was studiessystematically with the MMS-300thermo-mechanical simulator machine. Basedon the true stress-true strain curves, a hyperbolic sine function constitutivemodel which include flow stress、strain rate、and deformation temperature wasestablished, the deformation heating was modified and the strain was introducedin the constitutive model. The results show that the relative error and thecorrelation coefficient is7.29%and0.978respectively, the model can predictthe high temperature flow behavior of experimental steel accurately.(3)The behavior of austenitic coarsening and undercooled austeniticcontinuous phase transition of the experimental steel were studied respectively,and the continuous cooling transformation curve(CCT) were plotted. The resultsshow that when the temperature rises to1030℃, the austenitic tend to becoarsening，when the temperature rises to1070℃, the austenitic grain have beencoarsened severely; In addition, the experimental steel showed well in thehardenability, when the cooling rate is0.2℃/s, the microstructure is bainite, andwhen the cooling rate reach to1℃/S, the microstructure is martensite.(4) The quenching technology and tempering technology of experimentalsteel were studied, and the influences of QT technology and heat deformation onmicrostructure and mechanical properties were then considered. The resultsshow that heat deformation can improve the toughness of experimental steelafter heat treatment markedly, the hardness is611HV and the0℃impactabsorption reaches33J at the heat treatment parameter:90%heat deformation+970℃×30min Quenching+200℃×1h Tempering. The hardness and0℃impact absorption of experimental steel meet the requirements of high hardnessand high toughness for TBM disc cutter ring.