Effect of titanium on multiple pass high strength steel weld metal microstructures and properties
- Colorado School of Mines, Golden, CO (United States)
The use of high strength low alloy (HSLA) steel with yield strength greater than 100 ksi (690 MPa) is increasing. The two factors that strongly influence weld metal mechanical properties are heat input and chemical composition. This study investigated the effect of heat input and titanium additions on the microstructure and properties of high strength (>100 ksi), multiple pass 1.5Mn-3Ni-0.5Mo steel weld metal. Heat inputs of 1.0 kJ/mm and 2.2 kJ/mm were used to product weldments with three beads and two beads per layer following ISO-2560 [4] and Awas A5.1-69 [5] specifications, respectively. Six levels of titanium additions ranging from 5 ppm to 340 ppm were made to the low carbon 1.5Mn-3Ni-0.5Mo weld metals. The microstructure of the as-deposited weld metal within the top bead ws strongly dependent upon titanium content, with acicular ferrite (AF) replacing Widmanstaetten ferrite (FS(A)) in weld metals containing less than 60 ppm titanium for the 1.0 kJ/mm heat input welds and less than 104 ppm titanium for the 2.0 kJ/mm heat input welds. Weld metal yield strengths ranged from 96 ksi (660 MPa) at low titanium concentrations to 117 ksi (812 MPa) at high titanium concentrations. In conclusion, this study is unique because microstructures in the weld metal from which Charpy and tensile specimens were extracted were compared to as-deposited microstructures, thus revealing those compositions which produced microstructures resistant to the effects of multiple thermal cycles. Additionally, weld metals containing low titanium concentrations were found to be more sensitive to changes in heat input than the high titanium weld metals.
- OSTI ID:
- 115486
- Report Number(s):
- CONF-9404233--
- Country of Publication:
- United States
- Language:
- English
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