Induction Annealing of Austenitic Spring Steels for Nuclear Reactors

This paper describes designing and experimental trials of an induction annealing method for AISI 321H austenitic steel wires. Specifically, it explores the feasibility of incorporating an existing frequency controller into a wire drawing line to provide induction heating of the wire stock to annealing temperatures. In-process annealing is necessary to make cold wire drawing possible by restoring the ductility of the wire stock. The reason is that the wire products are required to have strengths in excess of 1600 MPa in some cases. Hence, the only way to meet this requirement is to apply severe deformation combined with sufficiently effective polygonization.

Real time optimization of temperature field in induction heating

Many induction heating processes must be controlled in accordance with the prescribed time evolution of temperature of the heated body (bodies). This requires a correct setting of field currents (amplitudes and frequencies) in the heating inductors that can vary either continuously or by steps. The paper presents a novel model of induction annealing of cylindrical aluminum billets based on solution of nonstationary forward and inverse tasks. The methodology is described in detail and illustrated with a typical example. Some of the results were verified experimentally.

Properties of Induction Reversion-Refined Microstructures of AISI 301LN under Monotonic, Cyclic and Rolling Deformation

In recent years, the efficient grain size refinement in austenitic stainless steels by the martensitic reversion process and the mechanical properties achieved in a laboratory-scale have been investigated extensively. In order to demonstrate the feasibility of this processing in an industrial-scale, a commercial 18Cr-7Ni-0.15N Type 301LN steel was cold rolled to various relative low thickness reductions (32–56%) to obtain 70–95% deformation induced martensite and subsequently annealed in an industrial-scale pilot induction line at the peak temperatures of 660–820 °C. Some sheets were subsequently cold rolled 10–20% to compare the mechanical properties with those of the commercial strengthened grades. Results showed that the induction annealing at around 700 °C can produce reversed structures with much enhanced tensile and fatigue strengths compared to those of the commercial steel. The stability of the grain-refined austenite is lower than that in the commercial steel, but still cold rolling strengthening remains ineffective.

Study of the Effect of in-Line Induction Annealing on a Set of Mechanical Properties of TP2 Copper Tube

Four specifications TP2 copper tubes experienced in-line induction annealing test was studied, mechanical properties of the tubes and the influencing factors were analyzed. The results show that mechanical properties and microstructure of different positions are stable and homogeneous after in-line induction annealing. Mechanical properties of the specimens are not only related to internal factors, but also related to external factors such as environmental temperature.