Effect of residual magnesium content on thermal fatigue cracking behavior of high-silicon spheroidal graphite cast iron

Journal Article · Tue Jun 01 04:00:00 EDT 1999 · Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science

DOI:https://doi.org/10.1007/s11661-999-0092-y· OSTI ID:677967

Cheng, C P; Lui, T S; Chen, L H ^[1]

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1. National Cheng Kung Univ., Tainan (Taiwan, Province of China). Dept. of Materials Science and Engineering

This study investigates the thermal fatigue cracking behavior of high-silicon spheroidal graphite (SG) cast iron. Irons with different residual magnesium contents ranging from 0.038 to 0.066 wt pct are obtained by controlling the amount of spheroidizer. The repeated heating/cooling test is performed under cyclic heating in various temperatures ranging from 650 C to 800 C. Experimental results indicate that the thermal fatigue cracking resistance of high-silicon SG cast iron decreases with increasing residual magnesium content. The shortest period for crack initiation and the largest crack propagation rate of the specimens containing 0.054 and 0.060 wt pct residual magnesium contents are associated with heating temperatures of 700 C and 750 C. Heating temperatures outside this range can enhance the resistance to thermal fatigue crack initiation and propagation. When thermal fatigue cracking occurs, the cracks always initiate at the surface of the specimen. The major path of crack propagation is generally along the eutectic cell-wall region among the ferrite grain boundaries, which the location of MgO inclusions agglomerating together. On the other hand, dynamic recrystallization of ferrite grains occurs when the thermal cycle exceeds a certain number after testing at 800 C. Besides, dynamic recrystallization of the ferrite matrix suppresses the initiation and propagation of thermal fatigue cracking.

• Sponsoring Organization: USDOE
• OSTI ID: 677967
• Journal Information: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Journal Name: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science Journal Issue: 6 Vol. 30; ISSN 1073-5623; ISSN MMTAEB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CAST IRON
CRACK PROPAGATION
CRACKS
MAGNESIUM ADDITIONS
METALLURGICAL EFFECTS
SILICON ADDITIONS
TEMPERATURE RANGE 0400-1000 K
THERMAL FATIGUE