Effects of High Temperature to Improve Hot Forging Process of SACM 645 Nitriding Steel

Abstract

SACM 645 nitriding steel is a commercial Cr-M0-Al medium carbon low alloy steel. Due to its good balance of strength, toughness and wear resistance the steel has been widely used for several general-purpose parts. Hot forging is a heat treatment method commonly used to increase the hardness of steel. The temperature and strain rate used in hot forging of steel results in changes in grain shape and size through a mechanism known as recovery, recrystallization and grain growth. There are common problems such as defect, net shape and cracked. The designer lacked of knowledge and understanding of the behavior of materials in hot forging process. This research aimed to study material properties under Hot forging at high temperature and effect of times annealing. Experiment, it was found that at 5 temperature levels, which were 850, 950, 1,050, 1,150 and 1,200 °C and annealing test in furnace temperature constant 800°C, holding time in furnace for 6 different times (1-6 hour). Therefore hot forging and the annealing test after hot forging concluded low temperatures, annealing time less result in small grain sizes and high hardness values. On the other hand, the higher temperature, annealing time long the larger the grain size and the lower the hardness. Consequently, the designer can use the information to improve the hot forging process, annealing determines the material properties of the finished products to the design of the part fabrication process.