Air hardening

Other martensitic grades are Types 501 and 502. The former has >0.10% and the latter <0.10% carbon. Both contain 4—6% chromium. These grades are also air-hardened, but do not have the corrosion resistance of the 12% chromium grades. Types 501 and 502 have wide appHcation in the petroleum industry for hot lines, bubble towers, valves, and plates. 

Luft-erhartung, /. air hardening, -erhltzer, m. air heater, -emeuerung,/. ventilation, -er-scheimmg, /. atmospheric phenomenon, -er-scheinungslehre, /. meteorology, -fahrt, /. 

Luft-hkrten, n., -hSrtung, /. air hardening, lufth rtend. a. air-hardening. 

A-2 3 4 4 4 3 2 4 1 Good abrasion resisiance. potishabtliiy Air hardening heat treat stable. 

Sampling time Slump Plastic air Hardened air Spacing Chord Specific... 

Sampling time (h) Stump (mm) Plastic air (%) Hardened air (%) Spacing factor (mm) Chord length (mm) Specific surface (mm1)... 

Medium Alloy Air Hardening Cold Work Steel A2 T30102 XI00 CrMoV5-l 1.2363... 

To obtain sap, a plant must be wounded by piercing the stem or by peeling off a thin layer of the bark. Most tree saps thicken and harden when exposed to the air, but some trees produce liquid resins. Air-hardened resins can be stored indefinitely in air-tight containers. 

Mortar masses on a purely inorganic basis consist of hydraulically setting components such as cement or gypsum that harden with water. In contrast to these products, there is nonhydraulically, that is, air-hardening mortar. 

Many steels are susceptible to cracking during or after welding. Examples include high-strength carbon steels and low-alloy steels such as the air-hardenable Cr-Mo steels. Preheating the base metal or substrate reduces the risks. Engineering codes [4] usually contain preheat temperatures and procedures. 

The austenitic stainless steels do not require PWHT as a hardness control measure. They are sometimes stress relieved or postweld heat treated to reduce residual stresses, thereby improving their resistance to stress corrosion cracking. The austenitic stainless steels are sometimes chosen in preference to the Cr-Mo low-alloy steels because PWHT can be avoided (the fusion zones of welds of the Cr-Mo low-alloy steels may be air hardenable). 

Welding Problems With Cr-Mo Pipe. Do not use low-chromium steel pipe unless you are willing to pay for more careful welding and post-weld heat treatments. At a given hardness, low-alloy chromium-molybdenum steels have somewhat more ductility than carbon steels. However, because they air harden so much, they usually require post-weld heat treatments to toughen the weld metal and heat-affected zone. This heat treatment complicates field welding. 

Moulds must resist high pressures without distortion, and resist wear over 10 cycles or more they are usually made from forged blocks of low-alloy steel, air-hardened after machining. Moulds act as thick-walled pressure vessels, with high tensile stresses in the walls. For a melt pressure of 50 MPa and a cavity diameter that is four times the wall thickness, the average hoop stress in the wall is 100 MPa from Eq. (C.21). Concave corners in the mould cavity act as stress concentrating features, so to... 

Carbides Steel, nitriding Steel, carburizing Steel, water-hardening Steel, oil-hardening Steel, air-hardening Nickel, cobalt alloy Steel, prehardened 44 Rc Beryllium, copper Steel, prehardened 28 Rc Aluminum bronze Steel, low alloy 6t carbon Kirksite (zinc alloy) Aluminum, alloy Brass... 

In alloyed air-hardened steels (13 CrMo44), thorough tempering at 750°C is needed after welding to eliminate the hardness structure. Only when the hardness is below 220V are these steels resistant to stress corrosion cracking. 

Low-molar-mass poly(butadiene) oils with 80%-97% cw-1,4 contents are produced with other Ziegler catalysts (for example, cobalt compounds with alkyl aluminum chlorides or nickel compounds with trialkyl aluminum and boron trifluoride-etherate). The products have few cross-links and dry as fast as wood oil and faster than linseed oil. Conversion of the poly (butadiene) oils with 20% maleic anhydride gives air-drying (air-hardening) alkyd resins. Modified poly (butadiene) oils stabilize erosion-endangered soils. Because of its low viscosity, the aqueous emulsion penetrates the surface soil layers. The surface crust is reinforced by an oxidative bonding process. Since no skin is formed on the soil crust, the aqueous absorption characteristics of the soil are retained. 

Laterite hardens on exposure to air. Hardening may be due to a change in the hydration of iron and aluminium oxides. 

Air Hardening A process used in steels that contain sufficient quantity of carbon or other alloys that will harden during air cooling. 

Air-hardening, medium-alloy, cold-worked steels... 

Nonhardenable grade for assemblies where air-hardening types such as 410 or 403 are objectionable. Aimealing boxes, quenching racks, oxidation-resistant partitions. 

Air-hardening medium-alloy tool steels (cold worked) A Air-hardening medium-alloy tool steels are best suited for applications such as machine ways, brick mold liners, and fuel-injector nozzles. The airhardening types are specified for thin parts or parts with severe changes in cross section, i.e., parts that are prone to crack or distort during hardening. Hardened parts from these steels have a high surface hardness however, these steels should not be specified for service at elevated temperatures. 

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