Content of FAILURE AND ANALYSIS in our journal

Published in last 1 year |  In last 2 years |  In last 3 years |  All Please wait a minute... For Selected: Download Citations EndNote Ris BibTeX Toggle Thumbnails Select Aging behavior of 60Si2MnA spring steel shims for steam turbine in nuclear power plant Jia Wenqing, Liu Siwei, Yuan Shuai, Xu Yingjun, Jia Kaili, Chen Mingya, Lai Yunting Heat Treatment of Metals    2020, 45 (10): 236-240.   doi:10.13251/j.issn.0254-6051.2020.10.045 Abstract （57）      PDF （551KB）（28）       Knowledge map    The 60Si2MnA spring shims locating at the bottom of the roots of steam turbine blades subject to various aging effects such as potential corrosion, fatigue, and stress relaxation during service.Thus the aging effects caused by corrosion, wear and fatigue during service were comprehensively analyzed for the spring shims at roots of the last blade and the secondary blade in the low-pressure rotors in a nuclear power plant, and the aging behavior and service life of the shims were studied.The results show that the surface of the spring shims after service for 10 years has wearing traces formed by fretting wear, however, no obvious corrosion products or morphology have been found,which implies that the corrosion effect has a limited impact on the service life of the spring shims in the course of long service. Besides,certain differences exist between the disassembled spring shim and the original state because the material shows obvious strengthening and hardening characteristics during the initial cycles.Therefore,it should be explicited by the power plant that the installation instructions for new shims are not applicable for the installed ones.Moreover, the used spring shim after service for 10 years is estimated conservatively to serve for at least another 5 years based on the practical operating state, in consequence, the existing maintenance and replacement cycle can be extended to save the overhaul period and economic cost. Reference | Related Articles | Metrics Select Reason analysis of punctiform and linear defects on GCr15 bearing steel ring after heat treatment Wang Deyong, Zhang Qun, Qi Rui Heat Treatment of Metals    2020, 45 (10): 241-245.   doi:10.13251/j.issn.0254-6051.2020.10.046 Abstract （78）      PDF （553KB）（52）       Knowledge map    Suspected crack punctiform and linear defects in the surface of the finished ring were found in the production of bearing steel inner ring, which was analyzed by using nondestructive detection, optical microscope, scanning electron microscopy, energy spectrum analysis. The results show that a few big size of aluminum oxide and silicate compound inclusions exist. By improving the purity of molten steel by adopting measures such as “high carbon pulling”, “white slag operation”, “soft blowing” and “protective casting”, the recurrence of punctiform and linear defects disappear. Reference | Related Articles | Metrics Select Cracking cause analysis of Cr12MoV steel cutting tool Wang Ning, Ding Beidou, Cui Meng , Feng Zhaoping Heat Treatment of Metals    2020, 45 (10): 246-248.   doi:10.13251/j.issn.0254-6051.2020.10.047 Abstract （89）      PDF （549KB）（26）       Knowledge map    Early cracking of a Cr12MoV steel cutting tool occurred during the period of service. The chemical composition, microstructure, hardness and fracture morphology of the Cr12MoV steel tool were investigated by means of direct reading spectrometer, metallographic microscope, Rockwell hardness tester, stereo microscope and scanning electron microscope (SEM). The results show that the main cause for the early cracking of the tool is the massive eutectic carbides with angled shape existed in the material, and another main cause is the unreasonable design of the screw hole concave platform which causes stress concentration. Reference | Related Articles | Metrics