30 Cr2ni4mov Steel Blocking Process Of As-cast Organization Evolution Law Research

As the main organization defects of heavy forgings, mixed grains may cause asignificant reduction in the performance, even worse may cause waste. The process of heavyforging is generally divided into two stages of blocking and forming. Due to thethermodynamic factor, deformation and the non-uniformity of the original organization in theblocking process, it necessarily cause the non-uniform of the organization, thus it have adirect impact for the organizational control in the late forming forging. So it is of greatsignificance to study the evolvement mechanism of the as-cast ingot coarse grain structure inthe blocking process for mixed grains’ formation mechanism and regulation research in thehot working process of heavy forgings.Starting from the source of hot working and taking30Cr2Ni4MoV steel of rotor asresearch objects, the organization structure of original as-cast ingot and evolvementmechanism in the processes of heating before forging and heat preservation and upsettingprocesses were studied by means of OM, SEM and EDS and a new evaluation method ofaustenite mixed grains has been put forward. It provide the scientific basis for mixed grainscontrol of heavy forging processing technology.Through the above research, grain shapes and hybrid forms of the ingot, the size anddistribution of the second phase and the influence on nucleation thermodynamics and kineticsof crystal nucleus grow up have been explicit under different heating temperature. The graingrowth law of uneven ingot casting in different heating conditions has been revealed. Thereason of mixed grains appearance is due to un-uniformity in original as-cast composition inthe process of grain growth when30Cr2Ni4MoV steel ingot casting sample is heated. Indifferent deformation temperatures and degrees in the organization transition process fromas-cast state to forging, the grain refinement mechanism, the size of grain, mixed grain degreeand deformation condition have been revealed by upsetting deformation. In addition, it hasbeen confirmed that the evaluation method in this paper is reliable by the experiment testingand data processing in the30Cr2Ni4MoV steel high temperature organization.