بررسي تاثير سيستم خنك كننده بر شرايط ايجاد ترك در فولاد DIN)55Cr3)

Study Influence of Quenching Environment on Formation of Crack in Steel 55Cr3(DIN)

Spring steels are generally applied in manufacturing of automotives parts specifically for suspension systems. The function of these systems is to maintain the axels under movement or brake torq ues or any other sudden vibrations during movement. Due to their safety functions, to avoid failure and accident for the car, these parts should be free from any kind of cracks. As these steels are used in quench and tempered conditions, the effect of quenching environment on cracking during heat treatment is studied in the present work. For this purpose, several random samples were selected from raw materials, 55Cr3 steel, and prepared similar to normal industrial production which is: austenitising, quench and tempering and shot blasting. Hardness test,metallographic examinations ,tensile test and crack detection were done on the samples and it was found that the conditions of oil and quenching pool are effective in formation of surface cracks in the parts during quenching sequence and the optimum conditions for each is introduced in the present paper