Study On Microstructure Control Of Ferritic - Pearlescent Microalloyed Non - Quenched And Tempered Steel

Micro-alloying non-quenched and tempered steel with ferrite and pearlite rely on the rational use of micro-alloyed technology and controlled forging and cooling technology to regulate the relationship with the various toughening organizational factors, obtain different mechanical properties required. This article explores inheat deformation parameters (deformation temperature, the amount of deformation, etc.) and the effect of Nb-V Mi-croalloyingto the microstructure and properties of the ferrite and pearlite fornon-quenched and tempered steel. It is important for non-quenched and tempered steel acquiringstable performance.In the thermal simulation test machine Gleeble-1500, the recrystalli-zation behavior of V added steel and Nb-V compoundadded non-quenched and tempered steel was studied. Contrast indynamic recrystallization process of V steel and Nb-V microalloying steel, found that with the higher deformation temperature, the lower the strain rate,the occurrence of dy-namic recrystallization more easy in micro-alloy steel. Comparethe static recrystallization of the steel, found the deformation temperature is the most important factor affecting the occurrence of static recrystallization.With the deformation temperature rising, the static recrystallization rate of V added and Nb-V compound added steel increased significantly. Further, the second phase precipitates affect the occurrence of static recrystallization significantly.On the Gleeble-3800thermal simulation testing machine, theexperi-ment steelswith forging test were reserarched.The impact of forging tem-perature, the amount of deformation, strain rate and cooling rate on the microstructure and properties of test steel were studying.It showed thatwith the deformation temperature reduced, the average size of pearlite group reducing, eutectoid ferrite increasing, the ferrite grain size is reduc- ing.Increase the amount of deformation will increase the distortion of the crystal grains, promote the formation of proeutectoid ferrite and improve the toughness of the organization. There are littledifferent between mul-ti-channeldeformation in short time and single-channel deformation on the steel of microstructureand performance. Increasing cooling rate can inhibit grain growing,refine the size of the ferrite improving the strength and toughness of the experimental steels. However, if the cooling rate too fast, it may appear bainite and bring adverse affects. In the temperature range of γ→α, With rapid cooling and then cooled slowly can refine organization and improve strength,obtained better organization than a single directly cools. The actual forging trial as reference the simulation results.In the process of forging, increasing the amount of pre-deformation can improve the tensile strength of V addedsteel.For Nb added steel, it can improve toughness significantly. Forging temperature also has significant effect on the performance of non-quenched and tempered steel. Forging temperature reduced can improve the strength and toughness of V steel. For Nb con-tained steel, it can increase toughness.