Study On Compaction And Forming Process Of 508-3 Steel Large Shaped Parts

Large-sized special-shaped parts are the main components of large-scale equipment.The comprehensive mechanical properties of the special-shaped forgings produced by the traditional forged welded flanges have been difficult to meet the requirements,and the overall forging forming process of large-sized shaped forgings is proposed.However,the overall forging process of large-sized shaped forgings doubles the weight and volume of the ingot,which will lead to a large increase in the probability of void defects inside the ingot,and it is more difficult to compact the internal cavity defects;In terms of the overall large-scale forging forming process,it is a great challenge for the forming equipment,and the profiled feature increases the difficulty of forming.In this paper,the difficulties of compacting the internal cavity of large ingots and the difficulty of forming large-scale shaped forgings in the production process of large-sized shaped forgings are carried out,which provides theoretical guidance for the actual production process.The main findings of the paper are as follows:(1)Study on the standard and critical value of hole closure inside the ingot.Through the finite element analysis method,the hole closing process of different sizes inside the ingot was studied.Three kinds of hole closure evaluation criteria such as equivalent strain,stress triaxiality and hydrostatic pressure integral value were selected,and the actual case was optimized by static water.The pressure integral value is used as the hole closure criterion to obtain the hole closure threshold and the void closure threshold.The hole closure critical value(Qcd)increases with the increase of the internal hole diameter ratio Rv.In the range of 1%?Rv?4%,the Qcd value increases from 0.313 to 0.529;in the range of 4%?Rv?8% The Qcd value is 0.529;in the range of 8% ? Rv ? 10%,the Qcd value is increased from 0.529 to 0.754.The void closure critical value(Qcd)increases with the increase of the internal initial void density,and finally reaches a certain value of 0.752.(2)Research on compaction effect of compaction process on large ingots.Based on the evaluation criteria of void closure and the critical value of void closure,the effect of compaction process on the internal compaction effect of ingot was studied.The research shows that the "WHF lengthening-upsetting-secondary WHF method lengthening" process is more effective than the "axial upset-WHF method lengthening" to achieve internal void compaction and void pressure of 508-3 steel large ingots.real.When the hole diameter ratio Rv?8%,the effective length ratio of the ingot is 100%;when the Rv is increased from 8% to 10%,the effective length ratio of the ingot is 87.5%;when the initial void density g?50 When % is used,the effective length ratio of the ingot is 88%.(3)Research on forming process of profiled forgings.The outer ring flange diameter(300mm,350 mm,400mm),mold temperature(20°C,100°C,150°C,200°C,300°C)and forging speed(10mm/s,15mm/s,20 mm,25mm/s)were studied by numerical simulation technology.the influence of the lubrication conditions(corresponding friction factors of 0.1,0.2,0.3,0.4,0.5,0.6,0.7)on the forming quality.The results show that when the outer ring flange diameter is 350 mm,a higher boss can be obtained under the rated forming force;the increase of the mold temperature cannot effectively reduce the forming load to obtain a higher boss,but can improve The lowest temperature of the boss portion;when the mold temperature is increased to 200 ° C,the mold has a tendency to deform.The reduction of the forming speed is advantageous for obtaining a higher boss,but the reduction of the forming speed causes the temperature of the boss portion to drop faster,which is disadvantageous for the formation of the boss.The reduction of the friction factor facilitates the formation of the boss and reduces the forming load,but when the friction factor is less than 0.5,the center of the boss is recessed,reducing the forming height.In summary,the flange diameter,friction factor and forming speed of the outer ring have a significant influence on the forming height of the boss of the shaped flange forging,and the influence of the forming height of the boss of the mold temperature shaped flange forging is small,the forging boss The optimized forming process is: the outer ring flange is 350 mm,the mold temperature is 150 ° C,the forging speed is 10 mm/s,and the friction factor is 0.5.