Abstract: A method for soft annealing of high carbon steel, characterized by taking objects to be soft annealed directly from a hot forming step and cooling to below Al−20° C.; heating the objects to Al+20° C. or above, and then cooling the objects down to beneath the Al temperature of the steel quickly as in air, which step is performed at least once; heating the objects to Al+20° C. or above, cooling the objects down to about 740° C., and then cooling the objects down to about 690° C. at a cooling rate of 3.5° C./min. or lower; and finally cooling the objects down to ambient temperature.

Abstract: A method of heat-treating a work piece of high-alloy steel by hardening involves relatively briefly annealing the work piece before hardening, followed by cooling the work piece. The brief annealing that is performed before the actual hardening and the ensuing cooling results in homogeneity of the material in the microscopic range. Following the annealing, the work piece is hardened, for instance by quenching in a salt bath, to achieve a super fine distribution of globular carbides in the microscopic structure with considerably reduced size as compared to the outset state. Also, the microscopic structure created by the method of the invention has improved toughness properties as well as increased microscopic structure stability to aging and leads to a longer service life.

Abstract: The invention relates to free-machining steels which do not rely on lead as a means of enhancing machinability. Instead, the steels of the invention employ concentrations of tin at ferrite grain boundaries to replicate a role of lead, which the inventors have discovered, in enhancing machinability. This role is to cause an embrittlement at the localized cutting zone temperatures by changing the fracture mode from transgranular to intergranular at those temperatures. The invention's use of concentrations of tin at the ferrite grain boundaries of the steel permits the machinability-enhancing effect to be obtained while employing bulk tin contents below the levels at which hot tearing becomes problematic. The invention improves over lead-bearing, free-machining steels in that the machinability-enhancing embrittlement produced by concentrating tin at the ferrite grain boundaries is both controllable and reversible.

Abstract: A method of making a heat treated steel casting comprising the steps of taking an "as-cast" steel casting comprising not more than 0.2% carbon, a total alloy content of less than about 4%, a carbon equivalent, as herein defined, lying in the range 0.45-0.7 and cooling the casting after performing the casting operation and then performing a heat treatment operation by re-heating the casting to a temperature above the AC.sub.3 temperature to homogenize the casting, then cooling the casting to an inter-critical temperature lying between the AC.sub.3 and AC.sub.1 temperature and then quenching to room temperature.

Abstract: A bainite forming process for treating a steel material reduces the time required for a complete thermal treatment as well as the cycle time for the thermal treatment device without necessitating any special means for handling the steel material. The steel material is heated to a temperature higher than the austenitic transformation point, and temporarily quenched to an intermediate point temperature higher than the martensitic transformation point. Then, the temperature of the steel material is again raised towards the range corresponding to bainitic transformation to form a bainitic structure. The reheating is discontinued before the temperature corresponding to the austenitic transformation point is reached, and the steel material is then quenched. In the heating steps, only the portion to be treated by the bainite forming process is locally irradiated with a high-density energy beam.