Experimental investigations on the effects of boriding and heating on aisi 1045 steel

Abstract

In this investigation, the effects of boriding and heating on the ductility, strength, and toughness of AISI 1045 steels are studied experimentally by using a shear punch test and the Charpy V-notch impact test. Boriding reduces the ductility, strength, and toughness of AISI 1045 steel samples in both shear punch test and impact test. The microstructures of powder pack borided AISI 1045 steel have three distinct regions namely (i) FeB zone (ii) Fe2B zone and (iii) Transition zone. The FeB, Fe2B, total and transition zone case depth increases with increase in boriding time. Grain coarsening effect is very severe in the case of borided steels as compared to the heated specimens due to poor thermal conductivity of iron borides. Grain size increases with increase in heating time and boriding time. XRD investigation confirms the formation of phases Fe2B and FeB. The nonuniformity of the boride layer increases significantly with an increase in the boriding time. Boriding increases the hardness of AISI 1045 steel by approximately 9 10 times. A peak surface hardness of 2115 ± 33 is observed in the case pack borided steel specimen treated for 3 h. Ferrite content is found to vary from 45% to 61% due to the effects of heating due to pearlite ferrite transformation. This may be due to the decarburization.The shear puch test results indicate that the boriding reduced the ductility by 5 25%, whereas the heating enhances the ductility by 5 12%. On the contrary, heating reduces the strength by 14 30% and the addition of boron compensates the loss significantly, and this further is enhanced by increasing the boriding time. Both boriding and heating enhanced the reduction in toughness by 38 45% and 12 23%, respectively.It has been concluded from the piercing profile that britlleness of AISI 1045 steel increases with increase in boriding time. The impact test results indicate that the fractured borided specimens exhibit brittle fracture. newline