Effects of Dynamic Strain Hardening Exponent on Abnormal Cleavage Fracture Occurring During Drop Weight Tear Test of API X70 and X80 Linepipe Steels

被引:23
作者
Kang, Minju [1 ]
Kim, Hyunmin [1 ]
Lee, Sunghak [1 ,2 ]
Shin, Sang Yong [3 ]
机构
[1] Pohang Univ Sci & Technol, Ctr Adv Aerosp Mat, Pohang 790784, South Korea
[2] Pohang Univ Sci & Technol, Pohang 790784, South Korea
[3] Univ Ulsan, Sch Mat Sci & Engn, Ulsan 680749, South Korea
来源
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE | 2014年 / 45A卷 / 02期
关键词
LOW-CARBON; IMPACT PROPERTIES; ACICULAR FERRITE; STRENGTH STEELS; MICROSTRUCTURE; PHASE; BEHAVIOR; TENSILE; RATES; SHAPE;
D O I
10.1007/s11661-013-2046-7
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
In this study, drop weight tear tests (DWTT) were conducted on API X70 and X80 linepipe steels fabricated with various compositions and rolling and cooling conditions in order to correlate the strain hardening with the abnormal cleavage fracture occurring in the hammer-impacted area. Area fractions of fracture modes were measured from fractured DWTT specimens, and the measured data were analyzed in relation to microstructures, Charpy impact energy, and strain hardening. All the steels consisted of fine acicular ferrite, together with some bainitic ferrite, granular bainite, and martensite-austenite constituent. As the volume fraction of acicular ferrite increased, the area fraction of DWTT abnormal cleavage fracture decreased because the toughness of acicular ferrite was higher than other microstructures. The area fraction of abnormal cleavage fracture was weakly related with strain hardening exponents obtained from the quasi-static tensile and compressive tests, but showed better correlation with those obtained from the dynamic compressive test. This tendency could be more clearly observed when steels having similar Charpy impact energy levels were grouped. Since the DWTT was performed under a dynamic loading condition, thus, the abnormal cleavage fracture behavior should be related with the strain hardening analyzed under a dynamic loading condition. (C) The Minerals, Metals & Materials Society and ASM International 2013
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页码:682 / 697
页数:16
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