Effect of TiN particles and microstructure on fracture toughness in simulated heat-affected zones of a structural steel

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

DOI:https://doi.org/10.1007/s11661-999-0019-7· OSTI ID:691381

Zhang, L P; Davis, C L; Strangwood, M ^[1]

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1. Univ. of Birmingham (United Kingdom). School of Metallurgy and Materials

Thermally stable TiN particles can effectively pin austenite grain boundaries in weld heat-affected zones (HAZs), thereby improving toughness, but can also act as cleavage initiators. The HAZs simulated in a GLEEBLE 1500 TCS using two peak temperatures (T{sub p}) and three cooling times ({Delta}t{sub 8/5}) have determined the effects of matrix microstructure and TiN particle distribution on the fracture toughness (crack tip opening displacement (CTOD)) of three steels microalloyed with 0.006, 0.045, and 0.1 wt pct Ti. Coarse TiN (0.5 to 6 {micro}m) particles are identified in steels with the two higher levels of Ti, and fine Ti(C, N) (35 to 500 nm) particles were present in all three steels. Large prior austenite grain size caused by higher T{sub p} decreased fracture toughness considerably in steels containing coarse TiN particles but had little effect in their absence. Fracture toughness was largely independent of matrix microstructure in the presence of coarse particles. Cleavage fracture initiation was observed to occur at coarse TiN particles in the samples with a large prior austenite grain size. Alloy thermodynamics have been used to rationalize the influence of Ti content on TiN formation and its size.

• Sponsoring Organization: USDOE
• OSTI ID: 691381
• 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: 8 Vol. 30; ISSN 1073-5623; ISSN MMTAEB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
FRACTURE PROPERTIES
HEAT AFFECTED ZONE
MICROSTRUCTURE
PARTICULATES
SIMULATION
STEELS
TITANIUM NITRIDES
WELDED JOINTS