The effects of double austenitization on the mechanical properties of a 0. 34C containing low-alloy Ni-Cr-Mo-V steel

Journal Article · Tue Mar 01 00:00:00 EST 1994 · Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States)

OSTI ID:7072952

Chang, E; Chang, C Y ^[1]; Liu, C D ^[2]

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1. National Cheng-Kung Univ., Tainan (Taiwan, Province of China). Dept. of Materials Science and Engineering
2. Taiwan Machinery and Manufacturing Corp., Kaohsiung (Taiwan, Province of China)

This article considers five different microstructures of a tempered martensitic 0.34C, 3Ni-1.3Cr-0.4Mo-0.1V steel through various heat treatments, including double austenitization (DA) treatments, and how the impact toughnesses are influenced by microstructure. Of the four mechanisms considered to explain the beneficial effect of DA treatment, the roles of retained austenite, grain-boundary embrittlement by impurity segregation, and matrix flow stress are discounted. The 50 pct fracture appearance transition temperature (FATT) of this steel is found to be dependent on both the grain size and the carbide dissolution. The conventionally treated steel contains mainly platelike M[sub 3]C carbides. The DA treatment helps to dissolve VC carbides and coarsen and spheroidize M[sub 3]C carbides in favor of the precipitation of short rodlike M7C3 carbides with a lower aspect ratio. The improvement of impact toughness (upper shelf energy, ductile-to-brittle transition temperature (DBTT), and lower shelf energy) by DA treatment, explained in detail, is attributed to a change of this material's tensile and work-hardening behavior affected by a variation of carbide morphology.

• OSTI ID: 7072952
• Journal Information: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States), Vol. 25:3; ISSN 0360-2133
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
LOW ALLOY STEELS
MECHANICAL PROPERTIES
MICROSTRUCTURE
CARBON ADDITIONS
CHROMIUM ALLOYS
CRACK PROPAGATION
FRACTURE PROPERTIES
MOLYBDENUM ADDITIONS
NICKEL ALLOYS
PHASE TRANSFORMATIONS
TEMPERING
VANADIUM ADDITIONS
ALLOYS
HEAT TREATMENTS
IRON ALLOYS
IRON BASE ALLOYS
MOLYBDENUM ALLOYS
STEELS
VANADIUM ALLOYS
360102* - Metals & Alloys- Structure & Phase Studies
360103 - Metals & Alloys- Mechanical Properties