Chemical effects on the weldability and fracture of molybdenum
Removal of oxygen and carbon from commercial-purity by hydrogen purification was studied. Low bulk-carbon levels were achieved and the removal of oxygen was found to be limited by other impurities, such as calcium, present in the starting materials. The purification treatments were nevertheless successful in removing uncombined oxygen, and the grain-boundary impurity contents for the purified materials were below detectable limits. Studies of the fracture behavior of the purified Mo indicated that segregation of interstitial impurities to grain boundaries was not inherently responsible for brittle intergranular fracture in Mo. Evaluation of the role of tensile test orientation showed that many of the conflicting results in the literature, with respect to fracture mode, can be explained by texture effects. The fabrication and service weldability of commercial-purity Mo denum were also studied. Dissolution of oxygen-bearing inclusions was found to be the dominant cause for porosity and centerline cracking in powder-metallurgy Mo welds. Doping with strong oxide-forming elements during welding was found to significantly improve the fabrication weldability of powder-metallurgy Mo.
- Research Organization:
- Lehigh Univ., Bethlehem, PA (USA)
- OSTI ID:
- 5306658
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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