High-temperature tensile deformation and thermal cracking of ferritic spheroidal graphite cast iron

Journal Article · Sat Feb 01 04:00:00 EST 1997 · Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science

DOI:https://doi.org/10.1007/s11661-997-0135-1· OSTI ID:474117

Cheng, C P; Lui, T S; Chen, L H ^[1]; Chen, S M ^[2]

---

1. National Cheng Kung Univ., Tainan (Taiwan, Province of China). Dept. of Materials Science and Engineering
2. National Taiwan Normal Univ., Taipei (Taiwan, Province of China). Dept. of Industrial Education

Ferritic spheroidal graphite (SG) cast irons of different silicon contents were used to study the tensile behavior in the temperature range of 500 C to near Ac{sub 1}. The thermal-cracking behavior under cyclic heating to various temperatures from 650 C to 850 C was also explored. According to the tensile data, the temperature dependence of the flow stress is concave upward, and that of the elongation is concave downward with drastic descent after reaching the maximum. The temperature range of ascending stress and descending elongation is above Ac{sub 1}, in which the eutectic cell-wall region transforms to austenite. Intergranular fracture with serious ductility loss can take place at 500 C, if the silicon content is too high (3.9 wt pct in this test). This brittle phenomenon can be eliminated through microstructure refining. As to the thermal-cycling test, it indicates that the thermal cracking occurs through intergranular fracture. Whereas the susceptibility to thermal cracking increases with increasing silicon content, it can be reduced by refining the microstructure. Unlike the cast irons heated above Ac{sub 1} with phase transformation, the heating temperature of about 750 C leads to the most severe thermal cracking. In addition, the specimens heated in air have lower thermal-cracking resistance than those heated in a neutral salt bath.

• Sponsoring Organization: USDOE
• OSTI ID: 474117
• 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: 2 Vol. 28; ISSN MMTAEB; ISSN 1073-5623
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CAST IRON
CRACKS
ELONGATION
FLOW STRESS
FRACTURE PROPERTIES
PHASE TRANSFORMATIONS
SILICON ALLOYS
TEMPERATURE DEPENDENCE
TENSILE PROPERTIES