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Welder’s Handbook
Globular Transfer – Mode of metal transfer across the arc where a molten ball larger than the electrode diameter forms at the tip of the electrode. On detachment, it takes on an irregular shape and tumbles towards the weld puddle sometimes shorting between the electrode and work at irregular intervals. Occurs when using shielding gases other than those consisting of at least 80% argon and at medium current settings. Gray Iron – A cast iron with 2%-4% carbon, in which the carbon is mostly in the form of graphite. Groove Angle – The total included angle of the groove between workpieces. H Hadfield Steel – The name sometimes used for austenitic manganese steel derived from its inventor. Hafnium – The metal used most commonly for the electrode emitter for air or oxygen plasma gases. Hardenable Steel – An alloy of iron that is subject to hardening when rapidly cooled. Hardening – Operation of quenching steels from the austenitic temperature range so as to produce martensite or a hard structure.
High Frequency – (as applied to gas-tungsten arc welding) An alternating current consisting of over 50,000 cycles per second at high voltage, low amperage that is superimposed on the welding circuit in GTAW power sources. It ionizes a path for non-touch arc starting and stabilizes the arc when welding with alternating current. High Frequency Discharge – High voltage power supplied to the plasma torch, which breaks down the air gap between the nozzle and electrode in order to initiate the plasma stream. High Speed Nozzle Design – Operates between 60-110 psig depending upon brand. Uses high pressure and divergency to produce 10-15% faster cutting speeds. High Sulphur Steel – Steel which has a sulphur content ranging from 0.12-0.33% and which then exhibits free cutting properties. Made for screw machine products High Speed Steel – Special alloy steel used for high-speed cutting and turning tools, as lathe bits; so named because any tools made of it are able to remove metal much faster than tools of ordinary steel.
High Strength Cast Iron – Cast grey iron with a tensile strength in excess of 30,000psi (206,900kN/M²).
Harsh – References the weld arc as being noisy, spattery or erratic.
Horizontal Welding Position – The welding position in which the weld face lies in an approximately vertical plane and the weld axis at the point of welding is approximately horizontal. Hot Crack – Also known as “auto crack,” resulting from stress concentration in relatively thin weld metal that is last to freeze. Both root cracks and crater cracks are forms of hot cracking. Hot Quenching – Cooling of heated metals or alloys in a bath of molten metal or salt, instead of using water or oil cooling medium. Hot Short – Metal that is brittle and unworkable above room temperature. Sulfur in steel causes a hot short condition. I Inclusion – Entrapped foreign solid material, such as slag, flux, tungsten, or oxide.
Heat Affected Zone – The portion of the base metal, adjacent to a weld, the structure or properties of which have been altered by the heat of welding. Heat Shield – A device which is located on the very front of a mechanized torch. Its purpose is to provide electrical isolation from the nozzle during piercing and cutting operations. In addition, it provides the path in which the shield gas impinges the arc at the exit orifice of the heat shield.
Heat Treatment – Any operation involving the heating and cooling of metals or alloys.
Helix of Continuous Welding Electrodes – The tendency of a length of the electrode to form a spiral when lying free on a smooth surface. Hertz – Hertz (Hz) is the symbol which has replaced the term “cycles per second.” Today, rather than saying 60 cycles per second or simply 60 cycles, we say 60 Hertz or 60 Hz. High Alloy Steels – Steels containing in excess of 10% alloy content. Stainless steel is considered a high alloy because it contains in excess of 10% chromium.
Impact Test – Measurement of the amount of energy required to rupture metals with sudden or shock loads.
Incomplete Fusion – A weld discontinuity in which fusion did not occur between weld metal and fusion faces or adjoining weld beads. Incomplete Joint Penetration – A joint root condition in a groove weld in which weld metal does not extend through the joint thickness.
High Carbon Steel – Steel with carbon content usually below 1.3% carbon, but may range from 1.0-2.0%.
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