การศึกษาวิธีการทวนสอบเครื่องทดสอบตีกระแทกแบบชาร์ปี้โดยวิธีทางตรงและทางอ้อมตามมาตรฐาน ISO 148:2008 ศุภชัย ทรงศักดิ์นาคิน 1*, และ สมนึก วัฒนศรียกุล, ภาควิชาวิศวกรรมการผลิต, คณะวิศวกรรมศาสตร์, มหาวิทยาลัยเทคโนโลยีพระจอมเกล้าพระนครเหนือ

The impact testing is the method to investigate for the material toughness. The impact testing machine needs an annual verification. The most favorite method to verify the impact testing machine is the direct method. Besides, the indirect method using reference material is also one of the favorite methods. At present, the reference material for impact testing has not been produced in Thailand. It is necessary to import from abroad. This research study aimed to investigate the verification of the impact testing machine. The verification was divided into two methods in conformity to the standard ISO148:2008: direct and indirect methods. The direct method studied the standard rules and methods in testing. The indirect method studied the production of the reference material for impact testing, especially the selection of material, heat treatment process, and the proper dimension of the reference material in conformity with the standard ISO 148:2008. The results of the study found that the steel that could be used to produce the reference material should be the steel of grade JIS SNCM439 or equivalent hardening at 860ºC x 90 minutes, quenching in 60ºC quenching oil, and tempered at 400ºC x 2 hours, for the range of low energy which gets the average hardness at 47 HRC and average impact energy at 20 J at 0ºC; then tempered at 650ºC x 2 hours, for the range of high energy which gets average hardness at 29 HRC and average impact energy at 130 J at 0ºC. The results from the impact energy testing of the reference material in both low energy and high energy have standard deviation conforming to the ISO148:2008, that could apply for reference material.