ANSI/AGMA C08 includes updated and extensively revised information from ANSI/AGMA B89 along with additional information needed to achieve . Download ANSI-AGMA B Gear Materials and Heat Treatment Manual. Index of AGMA Standards and Information Sheets by Number. 1 ANSI/AGMA B89 Gear Materials and Heat. Treatment Manual.
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Nitrided case depth is defined as the depth at which the hardness is equivalent to percent of the measured core hardness. Table presents chemical analyses of common wrought bronze alloys, while Table presents typical mechanical properties of these wrought bronze alloys in rod and bar form. Good machinability if annealed, or normalized and tempered to approximately HB or quenched and tempered to approximately HB.
Metallurgical aspects of gearing as related to rating allowable sac and sat values are not included, but, are covered in AGMA rating standards. Surface decarburization as defined for carburized gearing is a reduction in the surface carbon in the outer 0.
Size limitations and mechanical properties are listed in Table HBand steels are steels which are produced and purchased to a specified Jominy hardenability range. Normalizing results in higher hardness than annealing, with hardness being a function of agmma of steel and the part section thickness.
A test coupon is an appropriately sized sample often a bar used generally for surface hardening treatments.
ANSI/AGMA B89 (R) – Gear Materials and Heat Treatment Manual
Secondary operations such as repressing or sizing may be used to obtain precise control of shape and size or to improve mechanical properties. Microstructure will vary with the core hardness as related to steel hardenability, section size and quench severity.
There are two basic methods of flame or induction hardening gears, spin hardening and tooth to tooth hardening. Flame and induction hardened gearing generally distort less than carburized gearing because only the teeth are heated and subsequently quenched. Forging stock is always fully killed steel to minimize the occurrence of fissures due to dissolved gases during the forging process. Parts which are to be nitrided should have the following specified: The tempered hardness varies inversely with tempering temperature.
Surface hardness is limited by the concentration of hard nitride forming elements in the alloy and the core hardness of the gear. Usually an interval of 0. Wide faced gearing is heated by scanning type equipment while more limited areas can be heated by stationary inductors. The induction coil method is generally limited to gears of approximately 5 DP and finer.
Variables in the nitriding process are the combined effects of surface condition, degree of ammonia dissociation, temperature, and time of nitriding. Carburized case depth terms are defined as follows: Standards Subscriptions from ANSI provides a money-saving, multi-user solution for accessing standards.
However, normalized is preferred. Carbon content over 0. Jominy hardenability is expressed in HRC obtained at each interval starting at the water quenched end face.
[PDF] ANSI-AGMA B Gear Materials and Heat Treatment Manual – Free Download PDF
An inductor or flame head which encompasses only top lands of teeth and adjacent flanks followed by quenching provide wear resistance to the flanks, but endurance or bending strength in the roots is not enhanced.
Pockets which trap va- por bubbles and restrict the flow of quenchant should be avoided. The load in kilograms force listed in Table should be used. Carbon gradient can also be determined on the bar by machining chips at 0.
Repeatabiltiy becomes more difficult with flame hardening. If this bar meets the tensile requirements, the lot should be accepted. The quenching process is one of the major operations that influences the microstructure, hardness, mechanical properties and residual stress distribution, assuming the gear has been properly heated before the quench.
These processes are not available from commercial heat treaters. Hardness after tempering varies inversely with the tempering temperature used. Quenching, distortion, and shot peening are discussed. Tensile test bars for sand castings may be attached to casting or cast separately.
Effective case depth at roots are typically percent of mid tooth height case depths, and tips may be percent of mid tooth height case depths. This type of inspection may be necessary for accurate microhardness readings near the surface. Nitrided gears should not be specified if shock loading is present, due to inherent brittleness of the case. Weld repair in the tooth portion may require notification of the purchaser. Gearing may also be heat treated by other means, including laser heat treating and electron beam heat treating.
The quench needs to be fast enough to avoid secondary transformation products, but slow enough to reduce distortion and avoid cracking. Land width should be calculated before a case is specified. Spin flame and spin induction hardening generally produce the following distortion characteristics: Therefore, hardness determines the rating of the gear. The test coupon should be heat treated along with the gear s it represents.
ANSI-AGMA 2004-B89-1995 Gear Materials and Heat Treatment Manual
It is best to specify a hardness range and allow the heat treater to select the tempering temperature to obtain the specified hardness. Gearing may be subsequently given a refrigeration treatment to transform retained austenite and retempered. Mechanical properties of separate cast test specimens are shown in Table Wrought copper base materials is a general term used to describe a group of mechanically shaped gear materials in which copper is the major chemical component.
The ion nitride process uses ionized nitrogen gas to effect nitrogen penetration of the surface by ion bombardment.
Distortion is due to mechanical and thermal stresses and phase transformation.