A.I.S.I.-S.A.E. Tool Steel Type-None

Composite Forgings Ltd. SUPER HARDTEM analysis was the balanced chemical composition selected when the need arose for a strong shock resisting steel for use as insert holder dies for very large presses for the fabrication of large airframe structures. It is also recommended for use as large press dies where the severity of the application precludes the use of Hardtem.

GENERAL CHARACTERISTICS

SUPER HARDTEM possesses greater resistance to heat in forging operations without softening or washing, and greater resistance to mechanical and thermal shock from alternate heating and cooling than those normally found in the Hardtem Grade.

Numerous other applications have been found for this material such as those listed below.

ANNEALING

Heat slowly to 1550°F hold at temperature until heated through, then air cool to 400°F then heat to 1220°F, hold at temperature 1 1/2 hrs. per inch of cross section and air cool.

HARDENING

It is recommended that, in order to minimize scaling or decarburization, the finish-machined surfaces of dies and tools be protected against oxidizing atmospheres by heating the steel in a controlled atmosphere furnace. If this is not available, the steel may be heated in a neutral salt bath or in a conventional furnace with the steel completely packed in spent pitch coke, or similar material.

When only the impression-machined face of a die is to be protected, a convenient and inexpensive method is to immerse the die, impression face down, sufficiently deep into a packing material such as wood charcoal or spent pitch coke conveniently supported on a steel plate. The assembly may then be heated in an open-fired furnace. Charge the steel into a furnace at not over 500°F. When the steel is packed, charge into a furnace at not over IOOO°F. When a salt bath is used, charge the steel directly into the salt at the recommended hardening temperature. (It is recommended that a thermocouple be inserted in the box when pack heating.) When the steel is to be oil quenched, heat slowly and evenly to 1550°F at a rate not exceeding 200°F per hour. Hold at this temperature for approximately ½ hour per inch of cross section

QUENCHING

Cool small, thin and intricately shaped sections in still air to 350°F Cool heavier sections of deep impression and intricate design, under uniformly applied dry air blast, to 350°F.

Cool heavy sections with simple impressions and regular design to 350°F by complete immersion in a good quality of circulated quenching oil. Hold the die, impression face down, beneath the surface of the oil until the shank has chilled below the fire point of the oil. Partially withdraw the die to a level about ½ inch below the shank line, and maintain in this position until the impression face has cooled to approximately 350°F. Low melting temperature salt crayons may be advantageously used to determine this quench point.

TEMPERING

Immediately after air cooling or quenching to 350°F, place the steel into a tempering furnace maintained at 400F. to 500F. and thoroughly equalize at 500°F temperature. Then heat slowly and evenly to the necessary tempering temperature to give the desired hardness as shown in the following tables.

Hold at tempering temperature two hours per inch of greatest thickness up to and including a 3-inch section, increasing one hour for each one inch of increase over 3 inches. Air cool to room temperature.

Double tempering of SUPER HARDTEM is recommended. Hold at temperature one half the required single temper time and air cool to room temperature. Preheat to same temperature, hold same period of time and air cool to room temperature. Also differentially temper shanks to soften and toughen.

TYPICAL APPLICATIONS

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