Influence of Nitrogen on the Structure and Low Temperature Impact Properties of 304 Type Austenitic Stainless Steel Weld Metals by SMAW Process(Materials, Metallurgy & Weldability)
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Experimental covered electrodes (lime-titanic type) were made by selective additions of Mn-nitride or Cr-nitride to the electrode covering. 304LN stainless steel base plates (t=12mm) whose edge preparation was machined to single sided V, 60°included angle were clamped in a jig and were welded together by multi-pass shielded metal arc welding process. Nitrogen content of weld metals was adjusted by changing the content of Mn-nitride or Cr-nitride in the electrode covering. Effect of nitrogen on the microstructure of weld metal, δ-ferrite content, mean grain width, hardness and δ-ferrite secondary arm spacing were studied. Impact test for as welded specimen and solution treated specimen have been carried out at temperature range from 77K to room temperature. Influence of nitrogen on the impact value of weld metals was mainly discussed. Results obtained are summarized as follows: (1) δ-ferrite content in the weld metals in influenced largely by the nitrogen content. (2) Impact value of weld metals increases with increasing of the nitrogen content of the weld metals up to about 1700〜1800ppm after then the impact value falls as the nitrogen further increased. (3) The strengthening mechanism of weld metals due to addition of nitrogen is estimated that the effect of austenitic structure stabilized and interstitial solution hardening. Micro fissuring and precipitation of cluster (nitride) in excess of nitrogen containing weld metals decrease the impact value of weld metals. (4) Nitrogen content up to about 1700-1800ppm of weld metal which is introduced by SMAW process gives a good influence on the impact properties at low test temperature under condition of this study.
- 大阪大学の論文
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関連論文
- Influence of Nitrogen on the Structure and Low Temperature Impact Properties of 304 Type Austenitic Stainless Steel Weld Metals by SMAW Process(Materials, Metallurgy & Weldability)
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