Hadfield Manganese Steel
A specialty steel which is austenitic and usually contains approximately 12% Manganese. It is used in mining, earth- moving equipment and in railroad track work.
Hand Ladle Or Shank
A small ladle carried by one man. See Ladle.
Hard Sand Match (Match Plate)
A body of sand shaped to conform to the parting line upon which a pattern is laid in starting to make a mold. Sand is made hard by addition of linseed oil and litharge, Portland cement, etc. See Match.
Hardenability
In a ferrous alloy, the property that determines the depth and distribution of hardness induced by quenching.
Hardness
Resistance of a material to indentation as measured by such methods as Brinell, Rockwell, and Vickers. The term hardness also refers to stiffness of a material, or its resistance to scratching, abrasion, or cutting. See BHN, Brinell Hardness, Vickers Diamond.
Hardness/Brinell
Relative term referring to the resistance of a metal to plastic deformation from a given standard load applied on a standard penetration head. See BHN, Brinell Hardness, Vickers Diamond.
Head
The pressure exerted by a column of fluid, such as molten metal, water, etc.
Head Metal
The reservoir of metal in the feeder or riser of a mold. See Mold, Riser.
Heap Sand
Sand in piles on the foundry floor.
Hearth
That portion of a reverberatory furnace on which the molten metal or bath rests.
Heat
A single furnace charge of metal to be used for pouring directly into mold cavities; a heat may be all of part of a master heat. See Mold Cavity.
Heat Transfer
Transmission of heat from one body to another by radiation, convection, or conduction.
Heat Treatment
A combination of heating and cooling operations timed and applied to a metal or alloy in the solid state in a manner which will produce desired properties.
Heel
Metal left in a ladle after pouring, or in a furnace after or between tapping.
Heterogeneous Nucleation
The formation of nuclei within its own melt with the help of foreign substances or substrates is known as heterogeneous nucleation. The phase transformation takes place with the help of impurities, which lower the free energy.
High Pressure Mold
A strong high-density mold, made by air, hydraulic, or other squeeze process.
High Stress Grinding Abrasion
Abrasion that occurs when the abrasive is crushed between two opposing surfaces.
High-Alloy Steel
Ferrous alloy with more than 12 weight percent of noncarbon additions.
Hindered Contraction
Casting contraction during solidification and cooling which is hindered by mold or core restraints.
Holding Furnace
Usually a small furnace for maintaining molten metal at the proper pouring temperature, and which is supplied from a large melting unit.
Holding Ladle
Heavily lined and insulated ladle in which molten metal is placed until it can be used. See Holding Furnace.
Hollow Drill Test (Trepanning)
Removing a cylindrical sample from a metal section or structure to determine soundness of the section.
Homogenous Nucleation
The formation of nuclei within its own melt without the aid of impurity or foreign particles is called homogeneous or self-nucleation. This nucleation occurs in perfectly homogeneous materials such as pure (aluminium, copper, etc.) molten metals.
Homogenizing
A process of heat treatment at high temperature intended to eliminate or decrease chemical segregation by diffusion.
Horizontal Axis Casting Machine
A centrifugal casting machine in which the axis of rotation of the mold is horizontal.
Horn Gate
Curved gate in the shape of a horn arranged to permit entry of molten metal at the bottom of the casting cavity. See Casting, Cavity, Gate.
Hot Box Process
Method of making and curing cores within a heated corebox. To form and cure the core, the corebox is heated to approximately 500 degrees F. The sand used in this process contains a catalyst which hardens the binders in the core upon contact with the hot corebox. Complete curing while the core is still in the box results from the residual heat in the core, eliminating the need for conventional dryers or ovens. Frequently, cores created with the Hot Box process are shell cores. See Core.
Hot Deformation (Sand)
Change of form of a sand specimen which accompanies the determination of hot strength.
Hot Shortness
Brittleness in metal at elevated temperature.
Hot Spots
Areas of extra mass usually found at the junction of sections.
Hot Strength (Sand)
Tenacity (compressive, shear or transverse) of a sand mixture determined at any temperature above room temperature.
Hot Tear
Irregularly shaped fracture in a casting formed prior to completion of metal solidification resulting from stresses set up by steep thermal gradients within the casting during solidification and too much rigidity of the core or mold material. See Core, Solidification.
Hot Tears
Cracks in metal castings formed at elevated temperatures by contraction stresses. See Casting.
Hotbox Process
A furan resin based process which uses heated metal coreboxes to produce cores. See Core Box, Furans.
HSLA
Abbreviation for high strength low alloy steel. Steel with relatively high strength and impact properties. The carbon level is low and the alloying additions are significantly less than 5 weight percent.
Hunter Molding
Hunter molding is a sand molding process used to make sand molds. Hunter molding is yet another sand molding process named after the company that makes the machine, Hunter Automated Machinery Corporation. Hunter molding machines are horizontally parted matchplate molding machines, as opposed to the Disamatic vertically parted machines. See Disamatic Molding.
Hydrogen Embrittlement
A condition of low ductility resulting from the absorption of hydrogen. A time dependent fracture process which results in a loss of ductility. See Ductility.
Hypereutectic Alloy
An alloy containing more than the eutectic amounts of the solutes. Analogous to hypereutectiod. See Alloy.
Hypereutectoid
An alloy containing more than the eutectic composition. See Alloy, Eutectic.
Hypereutectoid Steel
A steel containing more than the eutectoid percentage of carbon (0.83 wt. %). See Eutectic.
Hysteresis (Cooling Lag)
Difference between the critical points on heating and cooling due to tendency of physical changes to lag behind temperature changes.
