Pq600 High-strength Engineering Machinery Steel Hot Rolling Process Research

In this article, the physical metallurgy process-the niobium steel austenite static state recrystallization behavior, the niobium carbon nitrogen compound in the austenite and ferrite physical metallurgy processes And so on-has conducted the research, depended on the PQ600 high strength engineering machinery structure steel which produces by Panzhihua Iron and Steel Company as the research object。Through the thermal simulation experiment, has studied the different hot rolling technological parameter how to influence the PQ600 high strength engineering machinery steel's organization, obtains the preliminary rolling parameter, unifies the scene the equipment condition, the rolling craft which Suited for the scene has Formulated.1.Determined the PQ600 high strength engineering machinery steel's static CCT curve, analyzed Nb how to influence the static CCT curve, studied different Cooling rate how to 'influence the organization of the PQ600 high strength engineering machinery structure steel. Nb joined expanded the ferrite formation region obviously, when the cooling rate from 0.14℃/S increased 10.00℃/S, the ferrite percentage increased, the pearlyte percentage reduced. When achieves 16.67℃/s, does not present the transformation of pearlyte, the austenite transforms directly into the bainite, the ferrite transforms the region to further increase. The bainite transforms initial temperature in 600℃about, so long as the Curl temperature to be higher than 600℃, may avoid the bainite organization forming.2.Carried on thermal simulation experiment, with the aid of the different technological parameters of single while going along and the multi-while going along, on the GLEEBIE-3500 thermal simulation testing machine, obtained PQ600 the high strength engineering machinery structure steel's basic hot rolling technological parameters. Through the research heating temperature to the austenite crystal grain size's influence, unifies PQ600 the strengthened characteristic, the heating temperature 1240±15℃is quite reasonable; Studied the different amount of deformity how to influence the organization: When 1010℃distortion, only then the amount of deformity is bigger than 30%, the austenite only then has the complete recrystallization, continues to increase the amount of deformity, the austenite crystal grain continues the refinement; But when 950℃distortion, the amount of deformity achieves 50%, will present certain mixed crystal phenomenon; Studied the finishing temperature and the Curl temperature how to influence the PQ600 high strength engineering machinery structure steel's organization:When 580℃the volume takes, in the organization has the massive bainite organization, but when 600℃-720℃the volume takes, organization is the ferrite & pearlyte. The PQ600 finishing temperature uses 870±20℃, the Curl temperature to use 660±20℃is quite reasonable.3.According to laboratory findings, unifies equipment's capacity of hot rolling Lumber yard of the Panzhihua Iron and Steel Co, carried on the industry trial manufacturing, analyzed the different finishing temperature how to Influence PQ600 high strength engineering machinery structure steel. When uses the high temperature termination rolling, the yield strength and the tensile strength are high,the low temperature impact value is low. Along with finishing temperature's reduction, the yield strength and the tensile strength reduce, low temperature impact value large scale enhancement. Nb separates out in the austenite in low temperature termination rolled steel volume, reduced in the ferrite the NbC separation quantity, the separation invigoration effect has weakened, the intensity reduced.