STUDIES ON THE HOT-WORKING STRENGTH OF STEEL (I)

The High Temperature-High Speed Tension Testing Machine

Abstract

In order to obtain the value 0f deforming strength of steels at high speed-high-temperatures corresponding to such hot-working processes as hot-rolling, forging, extrusion etc., the author specially manufactured a tension-testing machine. Main parts of this machine were as follows:
(1) Deformation speed of specimens at gage length conld be converted into 77/sec, 7/sec & 0.8/sec respectively.
(2) As for the direct resistance heating of specimens using direct current, rapid heating was possible within the range of 700°-1400°C. Actual measurements were done standardized by 800°, 1000°° & 1200°C.
(3) Tension stresss was measured by the use of a capacity-change pick-up and elongation was measured using inductance change. Recording was made by the use of an electromagnetic oscillograph (H-Vibrator).
Using this tension-testing machine, both nominal stress-strain curve and true stress natural strain curve in all deforming conditions of all types of steels were to be obtained, the latter being data of deforming the strength.
In this article, the design and construction of this testing machine, together with a suitable experimental technique were described in details.