Weld microstructure development and properties of precipitation-strengthened martensitic stainless steels
Precipitation-strengthened martensitic stainless steels provide excellent strength (170--220 ksi Y.S.) with high corrosion resistance. However, upon aging, a large reduction in toughness may also occur. The gas tungsten arc (GTA) cold wire feed process was used to weld half inch thick plates of PH 13-8 Mo and Custom 450 from which both tensile and Charpy specimens were machined. A fundamental understanding of the details of weld microstructural evolution was developed by liquid tin quenching GTA welds in which the solidification behavior, primary phase of solidification, microsegregation, and solid-state transformations could be followed. For both alloys studied, the as-welded yield strengths were similar to those of the unaged base material, 130 ksi. Weld properties were very similar to those of the base materials for both alloy systems. Weld strength increases significantly upon aging and achieves a maximum at intermediate aging temperatures. The increase in strength is accompanied by a large decrease in Charpy impact energy; however, the minimum in toughness occurs at aging temperatures slightly less than those resulting in peak strengths. The evolution of the weld microstructure was found to support predictions of microstructural modeling. Although a high degree of alloying partitioning occurs during solidification, a large degree of homogenization occurs upon further solidification and cooling as a result of solid-state diffusion.
- OSTI ID:
- 115473
- Report Number(s):
- CONF-9404233--
- Country of Publication:
- United States
- Language:
- English
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