No abstract

Triple melting (TM) by VIM+ESR+VAR has been highly successful for Alloy 718, large diameter ingots of Alloy 706, and high hardener alloys such as Alloy 720. Frequencies of ultrasonic indications for TM 718 are significantly lower than for VIM+VAR melt 718 because fewer clusters of inclusions are present, The cleanliness associated with TM 718 was verified by microscopy and by electron beam melting of buttons after VIM, VIM+ESR, and TM. Furthermore, white spot frequencies were found to be reduced for TM 718. Ultrasonic defect frequencies of Alloy 706 and Alloy 720 are also low. A major advantage of triple melting Alloy 706 is that ingots up to 36 inches (914mm) in diameter can be melted without freckles or positive segregation problems.

No abstract

An experiment was statistically designed to determine the effects of ten variables on the niicrostructure and mechanical properties of alloy 71 8 bar produced on Allvac's state-of-the-art, continuous, 10-stand rolling mill. A series of 32 rolling trials was conducted in which each \,xiable was set at one of two levels. Microstructures and mechanical properties lvere deteimined on samples taken after the material exited selected stands. Surface temperat~lres of the moving metal urere measured with pyronleters at six locations along the rolling mill.The grain size and mechanical properties after stand 4 are determined largely by the initial billet temperature. As rolling progresses, the speed of the finishing portion of the mill becomes increasingly important until it finally becomes the dominant factor. Correlations exist betm een surface temperature, n~icrostructure, and mechanical properties; these include the influence of delta phase distribution on stress-rupture properties.Experimental results agree m ell mith predictions of both surface and internal temperatures made ~vith a steady state, finite element model. The model is now available for optimizing rolling procedures.