Abstract
The distribution of boron and the microstructure of grain boundary (GB) precipitates (M23(C, B)6 and M2B) have been analyzed with their effects on the susceptibility of ductility-dip-cracking (DDC) and tensile properties for NiCrFe-7 weld metal, using optical microscopy (OM), secondary ion mass spectroscopy (SIMS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results show that boron segregates at GBs in NiCrFe-7 weld metal during the welding process. The segregation of boron at GBs promotes the formation of continuous M23(C, B)6 carbide chains and M2B borides along GBs. The addition of boron aggravates GB embrittlement and causes more DDC in the weld metal, by its segregation at GBs presenting as an impurity, and promoting the formation of larger and continuous M23(C, B)6 carbides, and M2B borides along GBs. DDC in the weld metal deteriorates the ductility and tensile strength of the weld metal simultaneously.
Original language | English (US) |
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Pages (from-to) | 1258-1267 |
Number of pages | 10 |
Journal | Journal of Materials Science and Technology |
Volume | 31 |
Issue number | 12 |
DOIs | |
State | Published - Dec 1 2015 |
Funding
The authors are grateful for financial support by the National Natural Science Foundation of China (No. 51474203 ) and Key Research Program of the Chinese Academy of Sciences (No. KGZD-EW-XXX-2 ). The authors also wish to recognize the assistance provided by China First Heavy Machinery Co. Ltd. in the welding process.
Keywords
- Boron
- Ductility-dip-cracking
- MB
- MC
- Tensile properties
ASJC Scopus subject areas
- Ceramics and Composites
- Mechanics of Materials
- Mechanical Engineering
- Polymers and Plastics
- Metals and Alloys
- Materials Chemistry