Workpieces are disposed between a pair of side walls in a heat treatment chamber. A centrifugal fan is disposed to face the workpieces inside the heat treatment chamber, and sucks gas from the workpiece side and generates air current. In regions at the respective side wall sides relative to an intermediate position between the pair of side walls, an air current regulation unit regulates the air current so as to restrict flows of the air current from the centrifugal fan to the respective side wall sides when a rotary blade of the centrifugal fan rotates in regions in which outer circumferential edge portions of the rotating rotary blade separate from the respective side walls, and allows the flows in regions in which the outer circumferential edge portions of the rotating rotary blade approach the respective side walls.

This free-cutting copper alloy includes Cu: more than 61.0% and less than 65.0%, Si: more than 1.0% and less than 1.5%, Pb: 0.003% to less than 0.20%, and P: more than 0.003% and less than 0.19%, with the remainder being Zn and unavoidable impurities, a total content of Fe, Mn, Co, and Cr is less than 0.40%, a total content of Sn and Al is less than 0.40%, a relationship of 56.5≤f1=[Cu]−4.5×[Si]+0.5×[Pb]−[P]≤59.5 is satisfied, constituent phases of a metallographic structure have relationships of 20≤(α)≤80, 15≤(β)≤80, 0≤(γ)<8, 18×(γ)/(β)<9, 20≤(γ).sup.1/2×3+(β)×([Si]).sup.1/2≤88, and 33≤(γ).sup.1/2×3+(β)×([Si]).sup.1/2+([Pb]).sup.1/2×35+([P]).sup.1/2×15, and a compound including P is present in β phase.

Exemplary alloys may be particularly suited for additive manufacturing applications, and may comprise iron and one or more of: chromium (Cr), nickel (Ni), carbon (C), and copper (Cu). Exemplary alloys may have a majority microstructure that is martensite.

A system for manufacturing a part is provided. The system includes a gantry, a first mobile arm and a second mobile arm, at least one conveyor and at least one sensor. The gantry has a first member and a second member disposed opposite the first member so as to define an opening. The first and the second mobile arms are disposed on the first and the second members, respectively. The at least one conveyor is operative to move the part through the opening so as to position the part within access of the first and the second mobile arms. The at least one sensor is operative to guide the first and the second mobile arms to one or more areas of the part. The first and the second mobile arms are operative to perform a manufacturing process on the part at the one or more areas.

A method for manufacturing a trunnion for a constant velocity joint, the trunnion having a plurality of journal units provided outside around a hub unit, the method including a first step of manufacturing the trunnion, a second step of thermally treating a rounded outer circumferential surface of the journal unit, and a third step of thermally treating a connection unit disposed between the journal unit and the hub unit and having a diameter smaller than that of the journal unit.

A method of manufacturing a stainless steel fastener includes following operations. Firstly, a stainless steel blank is prepared and contains from 1 to 3.5 wt % molybdenum, from 10 to 16 wt % chromium, from 0.5 to 3.5 wt % nickel, from 0.05 to 0.3 wt % nitrogen, carbon which is not more than 0.2 wt %, iron, and other inevitable compositions. Initially, a steel crystalline structure of the blank is martensite whose hardness ranges from 230 to 350 HV. Then, the blank is annealed to transform a partial crystalline structure of the steel crystalline structure into ferrite. The annealed blank experiences a cutting operation, a head forming operation, and a thread forming operation sequentially. Thereafter, a heat treating operation is executed to transform the partial crystalline structure from ferrite into martensite to complete a stainless steel fastener whose hardness is increased and is at least 500 HV, which facilitates a direct drilling effect.

A system includes a feeder configured to feed a continuous length of a tube at a predefined rate, a speed sensor configured to determine a feed rate of the continuous length of the tube, a first geometry sensor configured to determine one or more geometric dimensions of a portion of the continuous length of the tube, a first treatment station comprising a first entrance, a first exit, and a first heat treatment zone therebetween, the first heat treatment zone comprising at least one first zone heating element, and a controller configured to power the first zone heating element at a first heat treatment power level based on a first heat treatment target value, the feed rate, one or more of the geometric dimensions, and a first heating element value of the first zone heating element. The system may also include additional heat treatment and cooling stations.

A method and system for recovering a high yield of low carbon ferroalloy, e.g., low carbon ferrochrome, from chromite and low carbon ferrochrome produced by the method. A stoichiometric mixture of feed materials including scrap aluminum granules, lime, silica sand, and chromite ore are provided into a plasma arc furnace. The scrap aluminum granules are produced from used aluminum beverage containers. The feed materials are heated, whereupon the aluminum in the aluminum granules produces an exothermic reaction reducing the chromium oxide and iron oxide in the chromite to produce molten low carbon ferrochrome with molten slag floating thereon. The molten low carbon ferrochrome is extracted, solidified and granulated into granules of low carbon ferrochrome. The molten slag is extracted, solidified and granulated into granules of slag.

An aspect of the present invention relates to a high-strength steel, having excellent fracture initiation resistance and fracture propagation arrestability at low temperature.

The invention makes a steel available, which, in the case of edge-layer hardening without subsequent relaxation annealing, not only has the potential for developing a hardened edge layer having a great surface hardness, in particular a surface hardness that amounts to more than 820 HV1, but rather also possesses a ductile, fine-grained grain structure and, at the same time, can be easily welded. For this purpose, a steel according to the invention consists of (in weight %) C: 0.10-0.19%, Si: ≤0.15%, Mn: ≤1.0%, P: ≤0.015%, S: ≤0.015%, Cr: 0.2-1.0%, Ni: 0.7-2.0%, Mo: 0.5-1.0%, N: ≤0.015%, Al: 0.010-0.060%, Cu: ≤0.20%, B: ≤0.005%, as well as optionally, in each instance, one or more elements from the group “W, Ti, Nb, V, Ta” in content values in accordance with the following stipulations: W: 0.15-0.65%, Ti: 0.01-0.04%, Nb: 0.015-0.05%, Ta: 0.01-0.04%, V: 0.04-0.12%, and, as the remainder, of iron and unavoidable contaminants.