Research Information System
Thesis Type: Doctorate
Institution Of The Thesis: Gazi Üniversitesi, Fen Bilimleri Enstitüsü, Turkey
Approval Date: 2014
Student: YUSUF ARSLAN
Supervisor: AHMET ÖZDEMİR
Open Archive Collection: AVESIS Open Access Collection
Abstract:The performance change of the DIN 9861 standard punches which were made of AISI D3 tool steel and were subjected to the cryogenic treatment were studied and the effects of treatment were examined. At the beginning of study, the D3 tool steel punches were treated in three different groups such as I: cryogenic process at -145 oC for 24h (24HTC), II: cryogenic process 36h (36HTC) and III: cryogenic process 36h and then tempering process at 150 °C for 2h (36HTCT). The macro hardness values and the dimensions of punches were measured before and after the cryogenic treatment. Cryogenic treated (24HTC, 36HTC, 36HTCT) and non-treated (HT) puches perforated on the AISI 304 stainless steel sheet metal which has 1.5 mm thickness. Punched holes were carried out by 5, 6, 7, 8, 9 and 10 mm diameter punches under the dry conditions. The cutting feed of the sheet metal and the punch stroke were constent during the experiments. The weight lose of each punch was measured at the end of 6000th, 12000th, 18000th, 24000th, 30000th , 40000th piercing, the face and flank wears of punches, the SEM micro structure images were obtained by the microscope images. Also, the hole diameter, the hole circularty, the burr height, the burnished depth, the rollover depth and length and angle parameters were measured and evaulated. When taking into consideration the obtained values of these parameter, it is observed that the wear behavior and the sharpness of the punch tip of 36HTC and 36HTCT tools showed most positive effect than 24HTC tools. SEM, EDX, XRD analyses were made in order to determine the changes in the microstructure caused by criyogenic treatment and tempering with respect to tools. Microstructure examinations exhibited that criyogenical and tempering treatments reduced the carbide sizes, provided homogeneous carbide distribution, converted the retained austenite to martensite after the conventional heat treatment. These changes in the microstructure played a significant role in the increase of wear resistance of D3 tools. At the 40000 number perforation, it was decided that the cryogenic treatment had positive effects on the D3 tool steel punches aproximately 79% increased wear resistance.