Analysis of Quenching Crack Generation in Low Alloy Cast Steel by Using Heat Treatment Simulation

Accession number;05A0645824
Title;Analysis of Quenching Crack Generation in Low Alloy Cast Steel by Using Heat Treatment Simulation
Author; UCHIDA FUJIO (Akita Prefect.Inst. Industrial Technol, JPN) GOTO SHOJI (Akita Univ., Facutity of Engineering and Resource Sci, JPN) SHINDO RYOETSU (Akita Prefect.Inst. Industrial Technol, JPN) NAGATA SHIN (Akita Prefect.Inst. Industrial Technol, JPN)
Journal Title;Journal of Japan Foundry Engineering Society
Journal Code:G0096A
ISSN:1342-0429
VOL.77;NO.7;PAGE.437-444(2005)
Figure&Table&Reference;FIG.17, TBL.2, REF.14
Pub. Country;Japan
Language;Japanese
Abstract;In order to clarify the quenching crack phenomenon in cast steel, a disk shaped low alloy cast steep specimen with an opening was quenched in water at 1123 K. The generation of quench crack was studied by microstructure observation and analyzed by heat treatment simulation. The results obtained were as follows. (1) Quenching cracks form easily as the specimen volume increases. Quenching cracks occur due to time lag in martensitic transformation at the surface side and inner side of the quenched specimen. (2) Minute quenching cracks occur first at the boundary, alter which each microerack joined together and grew into a maincrack. (3) Moreover, the quenching crack showed a very sharp grain boundary fracture, and since the grain boundary strength was lower than that in transgranular, quenching cracks of low alloy steel casting materials are considered due to martensitic transformation stress in that mid and high temperature regions. (4) Heat treatment simulation showed quenching occurs at maximum principal stress concentration positions. The stress concentration location and quenching crack position are influenced by specimen shape. (5) Quenching crack generation was demonstrated by the heat treatment simulation, clarifying that the crack is generated not by heat stress but by martensite transformation stress. (author abst.)
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