Analysis Of 40Mn2 Ball Forging Defects And The Forging Process Optimization

As the largest and most important part in a ball mill consumption,grinding ball plays an important role in metallurgy, mine, electric power, building materials and other industrial fields.The consumption of steel ball every year in our country is above1.5 million tons,, Most of forging steel balls are produced by forge because of its low cost, good quality, high efficiency。For simple shapes of steel ball manufacturing,loose tooling forging is the most suitable because of its low production cost.This topic mainly aims to solve the problem of 40Mn2 ball appears crack defects in the actual production。Firstly,detect the quality of the finished ball product,then make tensile test and metallographic experiment on the raw materials of steel ball,Finally,analysis the forging process of the steel ball finding the cause of crack of steel ball,and optimize the forging process, to eliminate the internal crack of finished steel ball,then performed in two groups of simulation experiment on the forging process after optimization with the same material in the form of blank,under the premise of the parameter of the model experiment is equal to the actual production a set of experiments using the forging process before, another set of experiments with the improved optimization of forging process,The experiment shows:(1) There is no problem of hardness and the depth of hardening layer of steel ball products.(2) 40Mn2 steel raw materials tensile strength meet the national standards,does not exist any problem.(3) The defect level of banded structure in the raw materials of 40Mn2 steel ball is very high,serious area has reached the level 4,seriously affect the use of steel processing, is the main cause of cracks.(4)Heating before forging frequency is too high, the heating time is too short, will be easy to produce temperature stress,and raw material has the defects of severe banded structure, will also be easy to produce micro cracks when heating before forging.(5)Due to the loading direction forging deformation is distributed in parallel direction and banded structure,will be easy to micro cracks formed in the process of deformation,and then further expand in the quenching process.(6) Through simulation experiment,change the direction of loading, change the original bar along the axial to radial(a parallel with the direction of banded structure distribution),can eliminate steel internal crack, effectively improve and get better performance of steel forgings.The topic pointed at the problem of the stock of banded structure is easy to cause internal defects of steel ball forging product,in the case of without changing the rawmaterials with severe banded structure defects, through the optimization of steel ball forging process, change the loading direction of blank forging deformation, greatly reduces or eliminates the internal crack of forging steel ball, and greatly reduce the losses of enterprises, improve the qualified rate of products greatly, provides a feasible solution to the reuse of existing defects of steel banded structure.