Cooling Curve Based Estimation of Mechanical Properties in High Strength Steel Welds
The application of high strength steels in welded structures relies on easy to use quality assurance concepts for the welding process. For ferritic steels, one of the most common methods for estimating the mechanical properties of welded joints is the cooling time concept t8/5. Even without experimental determination, the calculation of cooling time with previously introduced formulas based on the welding parameters leads to good results. Because high strength structural steels and weld metals with a yield strength of 960 MPa contain higher quantities of alloying elements, the transformation start temperature Ar3 is found to be outside of the range of 800 °C to 500 °C. This leads to inadequate estimation results, as the thermal arrest caused by the microstructural transformation in this case is not considered. In this work the usage of the well-proven cooling time concept t8/5 is analyzed using high strength fine grained structural steels and suitable welding filler wires during gas metal arc and submerged arc welding processes. The results are discussed taking into account the microstructure and the transformation behavior. Based on the experimental work, an improved concept is presented.
C. Sommitsch, M. Ionescu, B. Mishra, E. Kozeschnik and T. Chandra
R. Sharma and U. Reisgen, "Cooling Curve Based Estimation of Mechanical Properties in High Strength Steel Welds", Materials Science Forum, Vol. 879, pp. 1760-1765, 2017