Using NDT Methods for Inspection Rolls of Cold （使用无损检测的方法检测卷冷）.pdf

18th World Conference on Non-destructive Testing, 16-20 April 2012, Durban, South Africa Using NDT Methods for Inspection Work Rolls 1 1 Pi-Kuan CHEN ,Kun-Yi Tsai 1 NDE Group, China Steel Corporation; 1 Chung Kang Road Hsiao Kang, Kaohsiung 81233 Taiwan, ROC Phone: +886(7) 8021111 ext3004; e-mail :043281@.tw Abstract The rolls used in Rolling Mill included different material and size, such as high alloy forged rolls, muti-casted iron rolls etc. The sizes are fromΦ360 mm toΦ1960mm, hardness layer in difference depth by heat-treatment. New rolls and used rolls are inspected by different NDT methods to make sure its in good condition for next rolling turn. In general, longitudinal UT used for internal defects and Rayleigh (Surface) wave UT or MPT/PT used for surface cracks. We also used ECT to measure the surface cracks during grinding roll process. Finally, we will measure the hardness, hardness layers and the residual stress in rolls. Keywords: Cold Roll Mill (CRM), Ultrasonic Testing (UT), Magnetic Particle Testing (MPT), Penetrant Testing (PT), Eddy Current Testing (ECT) 1. Introduction Rolls are important consumption items in rolling mill, new purchased rolls are needed to confirm the quality to a certain level before it can be used on the rolling line. Roll of CRM is directly rolling on steel strip, requiring high hardness and high toughness material characteristics. Therefore most of the work rolls are forged steel and common injuries are collisions, fatigue and stress concentrations, which caused surface cracks. The NDT inspection methods includ e detection of surface defects and internal de