Cryogenic cooling – a new concept of refining grain structure in Ferritic Stainless Steel (FSS) Welds
Excessive grain growth in Ferritic Stainless Steel (FSS) welds causes severe loss in mechanical properties which limit the usage of this low cost stainless steel in many structural applications. The energy input to create the weld pool and the heat dissipation rate upon re-solidification of the melt...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Trans Tech Publications, Switzerland
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| Subjects: | |
| Online Access: | http://irep.iium.edu.my/6069/ http://irep.iium.edu.my/6069/ http://irep.iium.edu.my/6069/1/Grain_refinement_by_Cyogenic_cooling.pdf |
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| Summary: | Excessive grain growth in Ferritic Stainless Steel (FSS) welds causes severe loss in mechanical properties which limit the usage of this low cost stainless steel in many structural applications. The energy input to create the weld pool and the heat dissipation rate upon re-solidification of the melt and beyond is responsible for grain growth in the weld section. Several schemes are available to refine the weld structures but none of them can control the dimensions of the weld zones. Dissipation of weld heat is possible to expedite by controlling the energy input and also by incorporating additional cooling system. In this work a cryogenic cooling system was applied in controlling the weld size and the microstructures. This new scheme produced a refined and equiaxed grain structure. Compared to the conventional weld, the cryogenic cooling reduced the weld size by more than 30% and provided about 45% grain refinement. No changes in phase structures were found by cryogenic cooling except a little more delta ferrite in the microstructure. However, the hardness distribution gave slightly higher profile in the cryo-cooled welds because of smaller grain structures produced by the faster cooling effect |
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