Moly-Telastic is a medium carbon, chromium-molybdenum type cast steel which is similar to an AISI 4135 specification, except with reduced chromium content. It can be heat treated by annealing or normalizing and tempering to an approximate hardness of 180 HB for all section sizes.
	No. 1 Gearalloy is a medium carbon, chromium-nickel-molybdenum type cast steel used for applications requiring higher harden ability than Falk Moly-Telastic. It is similar to an AISI 8630 steel, but higher in alloy content.
	No. 2 Gearalloy is a low carbon (0.20% nominal), chromium-nickel-molybdenum type cast steel containing 0.04-0.06% vanadium for grain refinement in gear castings. Chemistry is similar to an AISI 8620 steel, but higher in alloy content. This is our standard cast steel for carburized and hardened gears and has comparable harden ability to an AISI 4320 H steel. It is also used in the through-hardened, quenched, and tempered heat treat condition to a maximum hardness range of 245-285 HB for impact applications (this condition is not intended for gearing or wear applications).
	No. 3 Gearalloy has higher carbon and molybdenum content than No. I Gearalloy This results in higher harden ability for increased section size or higher hardness ranges for quench and temper heat treatment. It is similar to an "8633" steel (not a standard AISI designation) but higher in alloy content.
	No. 4 Gearalloy has higher carbon content than No. 3 Gearalloy. This results in the highest harden ability alloy cast steel (maximum section size or maximum hardness) intended for hardening by quench and temper The harden ability is equivalent to an AISI 4340. Chemistry is similar to an AISI 8640 steel but higher in alloy content.
	No. 6 Gearalloy has the same carbon content as No. 4 Gearalloy but has increased alloy content. This enables hardening by normalize and temper heat treatment to higher hardness ranges (325-365 HB maximum) than can be achieved with No. 4 Gearalloy normalized and tempered. No. 6 Gearalloy is not intended to be quench hardened because of quench cracking susceptibility.

Moly-Telastic and No. I through No. 4 and No. 6 Gearalloy grades of alloy cast steel do not, by intent, conform to specific standard SAE or AISI steel designations regarding carbon and alloy content, but contain modified carbon and generally higher alloy content for improved depth of hardening (harden ability).

The chemical analyses for our Moly-Telastic and Gearalloy grades of alloy cast steels are shown in Table 1.

Our alloy cast steels can be heat treated to meet the strength requirements of ASTM A148 (High Strength Steel Castings for Structural Purposes) up to grade 165-150. Minimum tensile ductility values (elongation and reduction of area) for corresponding strength levels are shown in Table 2.

Other alloy cast steels which meet your specifications can be furnished for special pressure, low temperature and high temperature applications.

The selection of the appropriate alloy cast steel depends upon specified chemistry, hardness, strength and design considerations.

We will assist you in the proper selection of the appropriate grade to meet your design requirements.

Machinability and Processing
Alloy grades of cast steels (Moly-Telastic and Gearalloy grades) are readily machinable and ductile, due to our ladle deoxidation practice which uses primarily calcium and not aluminum. This, in itself, can easily result in lowering machining costs by as much as 15%.

A well equipped sand laboratory monitors sand molding and core making practices. A sodium silicate sand binder is exclusively used in our core making process. This high grade material requires no oven curing, is environmentally safe, and drastically reduces potential metal solidification defects.

Pattern molding can accommodate items up to 150" in diameter or diagonal. Beyond 150'*. We utilize sweep or pit molding. The largest pits measure 24' x 50' x 7.5' and 36' x 36'x 10'.

The use of aluminum is limited to castings less than 8T finish weight, as it develops aluminum oxides and decreases machinability. Aluminum content used is less than 0.020%. The index of machinability, shown in Table 10, is based on hardness and is related to machinability of B1112 steel (100%).

Although microstructure considerations, as well as hardness, determine machinability, our machinability rating system is based on tool life as a function of cutting speed (surface feet per minute).

Mechanical Properties
Mechanical properties of steel castings are generally determined from test bars machined from standard ASTM A781 test coupons. These test coupons may be attached to the casting or cast separately.

Minimum tensile properties, obtained from standard cast test coupons, for our alloy cast steels are shown in Table 2.

Test bar results for tensile ductility (per cent elongation and reduction of area) and impact strength may not be representative of actual castings due to harden ability and section size considerations. Strength properties such as tensile, yield, and to a lesser degree, endurance or fatigue strength, show better correlation between test bars and actual castings, provided hardnesses are equivalent. For further information regarding the limitations of test bar data, please contact our Materials Technology Department through your local Rexnord account executive.

Impact Properties
Typical Charpy V-Notch impact strengths for Moly-Telastic and No. I through No. 4 Gearalloys are shown in Tables 3 through 6. These values were obtained from separate cast keel blocks and 5.0 & 10.0 inch test sections. Impact strength is also a function of heat treatment, hardness and test temperature. Impact properties were evaluated at T/3 depth for test sections.

Table 3 is the typical Charpy V-Notch impact strength for Moly-Telastic cast steel in a 5.0 test section in the normalized and tempered (N&T) condition at 160-200 HB.

Impact strength in the quenched and tempered condition is higher than for the normalized and tempered condition. Specific data may be obtained upon request.

For applications requiring higher impact strength, due to shock loading and/or low ambient temperatures, No. I or No. 2 Gearalloy is recommended depending on the specified hardness.

Table 4 shows the typical Charpy V-Notch impact strength (ft-lbs.) for keel blocks of No. I Gearalloy cast steel, as a function of heat treatment and specified hardness.

Table 5 shows the typical Charpy V-Notch impact strength for No. 2 Gearalloy cast steel at 70*F in the water quenched and tempered condition at 207-223HB.

Table 6 shows the typical Charpy V-Notch impact strength for No. 4 Gearalloy cast steel (5" and 10" section thickness) according to hardness in the oil quenched and tempered condition.

Metallurgical Considerations
Harden Ability
Control of melting is accomplished through computer-aided harden ability (Di) calculations, coupled with statistical process control in order to ensure uniform response to heat treatment.

The ideal critical diameter (Di) is defined as the diameter of a round that can be quenched under ideal conditions (ice brine) in order to obtain a 50% martensitic microstructure at the center of the section. The multiplication factors for calculating (Di) harden ability, which vary according to ASTM grain size, carbon, and individual alloy content, are available in literature and from the Materials Technology Department.

Cast (Di) harden ability ranges, established in our Melt Shop as acceptance criteria for our heats, are shown in Table 7.

The harden ability ranges are presented for reference purposes only and should not be considered as part of a material specification. They are intended to illustrate the degree of control used during manufacturing to assist in the production and heat treatment of castings, and may be subject to slight modification.

Jominy End Quench
Jominy end quench harden ability ranges from testing alloy cast steels per ASTM A255 are shown in Figures I through 4. For the same reason cited above for (Di), these Jominy end quench curves should not be part of a material specification. harden ability ranges in Figures I through 4 are narrower than those for wrought AISI designations, as illustrated in Figure 4 for No. 4 Gearalloy. Jominy end quench curves were not developed for No. 6 Gearalloy as the curves were expected to be nearly horizontal and No. 6 Gearalloy is not quench hardened.

Weldability
Moly-Telastic and Gearalloy grades can be welded satisfactorily, providing that necessary preheating and post-heating precautions are followed. Minimum preheating temperatures are shown in Table 9.

The maximum preheat temperature should not be greater than 200 F above the minimum required. Minimum preheat temperature should be maintained during welding by torch heating and monitored by temperature indicating pencils or a surface pyrometer.

The stress relieving temperature should be 1000-1250°F for annealed castings and 50-1 00°F below the final tempering temperature for normalized and tempered or quenched and tempered castings of all grades.

Whenever possible, furnace preheating and post-heating are preferred to local heating with large torches. The choice of electrodes and welding techniques is normally governed by the nature and position of the weld and the mechanical properties required. Low hydrogen type manual arc weld rods, or CO2 shielded flux core process wire, selected on the basis of the required strength, are recommended. When the deposited weld metal is designed to meet the tensile properties of the casting, welding before heat treating, using heat treatable electrodes, e.g., 4340, is recommended.