| Steel ball is a huge consumables used for electric power,coal chemical industry,metallurgical etc.The consumption is tremendous in the internal and the external market.The main production processes have casting,forging,skew rolling etc.The production efficiency of rolling steel ball is five times more than casting and forging.The rolling steel ball has excellent product performance.But the large diameter rolling steel ball making in the internal crack easily.The paper provides important gist for large diameter rolling steel ball by seeking new test and token methods of material quality and steel ball wear resistance.It has important significance for industrial development and application of steel ball.The paper uses infrared spectrometric analyzer to analyz component,hot acid etching method to observe low-magnification defects,metalloscope observing inclusion and microstructure,SEM observing fracture surface pattern for failure steel ball and blank,and analyzes forming and heat treatment of failure steel ball.Test the fatigue life of steel ball in the height of 7.5m.Do impact testing by using 8mm×10mm×55mm non-notched and 10mm×10mm×55mm notched impact specimens,and observed the impact fracture by SEM.The results are as fellows:(1)Big size non-metallic inclusion in steel ball blank,high heating temperature of rolling,too fast quenching speed will reduce the impact fatigue life of steel ball.(2)The microscopic cracks emerge in coarse needle martensite transition process to reduce the steel ball impact fatigue property.Decreasing heating temperature of rolling can make the needle martensite becoming thinner,reduce the influence of microscopic cracks to steel ball,increase the impact fatigue life.(3)Too fast quenching speed will cause big transformation stress,increase the influence of microscopic cracks to steel ball.Quenching by low concentration of water glass can slow sown the speed of martensite transition,reduce the influence of microscopic cracks to steel ball,increase the impact fatigue life.(4)Used high quality blank,reduced heating temperature of rolling,and quenched by low concentration of water glass,the impact fatigue life of steel ball is up to 12897 times,the impact fatigue life is greatly improved.(5)The sample with inclusions less than 15.47μm has high impact toughness,the impact toughness is effected by the quantity and size of the inclusions.Analysis of impact toughness and the inclusions in impact fracture,combined the inclusion rating and porosity distribution can increase the reliability of choosing material.(6)When the grinding condition changed,the abrasion mechanism of the steel ball in the ball mill will change.By simulating the actual working conditions,in the premise of ensuring the ball has a certain impact,reducing ball charge,reducing the test input,and studying on wear resistance of steel balls in different milling conditions,has good development prospect. |
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