Study On The Production Process And Fatigue Property Of The Powder Forging Connecting Rod (3.8L)

The connecting rod is the key mechanical part for the automobile engine,and its quality affects the overall performance of the engine.With the increasingly requirement of the car engine power,fuel,vibration and noise performance,it is become a trend to reduce the quality but guaranteed the performance of connecting rod at the meanwhile.New technology of powder forging two rode gradually applied to the automobile industry.Due to the stress of connecting rod in the engine cycle,it determines the connecting rod’s performance is the fatigue strength.there are many factors which can influence on the fatigue strength performance,and raw material proportioning,setting of process parameters,the density of powder forging are most important.This paper research the above three factors affecting the performance of powder forging connecting rod fatigue as well as the interaction relations.It takes the 3.8L connecting rod for example,from the production technology of powder forging process,the surface compressive stress test and fatigue test,and it provides the basis for the powder forging connecting rod research and development,verity whether the powder forging connecting rod fatigue strength meet the design requirement.The production of powder forging:The test of powder forging connection rod fatigue always adopts the single point method and groups of conventional test method,it preliminary determine the fatigue strength,then draw the S-N curve according to the fatigue test results.In this paper,the analysis of the factors which affect the powder forging connecting rod fatigue performance shows in macroscopic and microscopic of connecting rod fatigue fracture.A number of factors which can affect the fatigue performance of a connecting rod,there are three fatigue tests in order to get more accurate test results of powder forging connecting rod fatigue,in the previous two,according to the fatigue fracture macropicture,determine the cause of low fatigue test result,change the parameter setting,so that the third tie test go smoothly.Finally,it is 269.1Mpa under 1×10~7 conditions.In the factor of influence the performance of the powder forging connecting rod fatigue,it use the metallographic picture,scanning electron microscope and energy spectrometer to analysis both in macroscopic and microscopic.In the macro picture,it found the fatigue fracture crack source,crack spreading area and transient breaking area;in the micro analysis,it compares and analyzes the and surface and internal structure,the organizational structure picture and Fe,Cu,S,Mn,C distribution to determine the factor of influence on the performance of the powder forging connecting rod fatigue.