Examinations of casting cracks in a high alloy steel valve

Abstract

High alloy steels are widely used for high temperature and corrosion resistance applications in power plants, e. g., in chemical and petroleum industries. Mechanical properties of these alloys (e. g., hardness and tensile strength) can be altered by suitable heat treatment. This paper deals with failure investigations of a cast valve made of high alloy steel. The samples were taken from valve body and prepared by metallographic techniques. Microstructural defects causing cracking were investigated using light microscopy and scanning electron microscopy/energy dispersive X-ray spectrometry. Segregation areas at the grain boundaries in the microstructure of the material were observed. Casting was repeated by taking necessary measures during the production in order to eliminate these heterogeneous regions and then suitable heat treatment was applied to the part. The samples taken from the last part were also examined. As a result, a homogeneous microstructure was obtained and no macro or micro cracks were observed.

Automatic Cutting System Design of Robot Hand Based on Stereo Vision

“…e pouring riser which is inevitable in the cast process should be cut out as "excess" for subsequent machining. At present, the pouring riser is cut with a hand-held abrasive cutting machine basically which has high labor intensity and low efciency [5][6][7]. Large amounts of metal dust and smoke from cutting process oat in the air and cause environmental pollution.…”