In order to develop new high manganese non-magnetic steels that can be employed to extensive applications ranging from cryogenic to elevated temperature uses, the effects of C and Mn on their magnetic permeability, thermal expansion coefficient and mechanical properties are investigated.
It is found that the relation between thermal expansion coefficient, β, and both C and Mn contents can be expressed by the following linear regression equation: β(×10^-6/°C)=17.66+3.82C(%)-0.22Mn(%). Good mechanical properties are exhibited in the wide range of Mn contents between 18% and 30% at room temperature, while there is a tendency that this optimum range of Mn content is narrowed at cryogenic temperature.
Then, H-shapes, round bars and deformed bars are manufactured at the workshops using 5t vacuum melted ingots, aiming to establish the conditions for practical processes for final products and to study such various characteristics of the products as their physical and mechanical properties, machinability and weldability. As a result, it is shown that all of those products have excellent properties as non-magnetic steels.
In addition, the manufacturing of non-magnetic pinch rolls attached to the electro-magnetic stirring equipment on the continuous casting machine is described in detail as one of the practical applications of the high Mn non-magnetic steels.