TCI Precision Metals announced the expansion of its precision sawing services to meet the demands of customers wanting more flexibility in materials processing. Customers with needs ranging from precision sawing to six-sided precision machine-ready blanks can now be accommodated. Computerized precision sawing helps TCI to serve more of the customer’s materials needs. TCI sources aluminum, stainless steel, and other alloys mill-direct, which supports customers needing value-added materials, but the Company also works with customer-supplied materials.
This report discusses grain size and its influence on metallurgical properties including its effect on yield strength, ultimate strength, fatigue strength, and fracture toughness. Also discussed are manufacturing issues such as heat treatment, hardenability, and machinability.
The AGMA Aerospace Gearing committee is seeking new committee members to revise AGMA 926-C99, Recommended Practice for Carburized Aerospace Gearing. Specifically, metallurgy and heat-treating experts are needed. This information sheet recommends material case properties, microstructure, processing procedures, and other critical parameters for carburized aerospace gears. Due to the unique requirements of aerospace gearing, such as typically smaller lot sizes, demands for higher precision, and stringent quality requirements, this information sheet aims to provide deeper, aerospace-specific information than other already published metallurgical specifications such as AGMA 923, Metallurgical Specifications for Steel Gearing or AMS2759/7, Carburizing and Heat Treatment of Carburizing Grade Steel Parts.
Tiger stripes on a high-speed pinion made of a carburized SAE 9310 steel were investigated. The morphology of the damage was typical of electric discharge damage. The cause of the stripes and potential damage to the gear tooth were analyzed and are presented in this report.
Understanding the morphology of micropitting is critical in determining the root cause of failure. Examples of micropitting in gears and rolling-element bearings are presented to illustrate morphological variations that can occur in practice.
Gears are designed to be manufactured, processed and used without failure throughout the design life of the gear. One of INFAC's objectives (*see p.24) is to help manufacture of gears to optimize performance and life. One way to achieve this is to identify failure mechanisms and then devise strategies to overcome them by modifying the manufacturing parameters.
Ausforming, the plastic deformation of heat treatment steels in their metastable, austentic condition, was shown several decades ago to lead to quenched and tempered steels that were harder, tougher and more durable under fatigue-type loading than conventionally heat-treated steels. To circumvent the large forces required to ausform entire components such as gears, cams and bearings, the ausforming process imparts added mechanical strength and durability only to those contact surfaces that are critically loaded. The ausrolling process, as utilized for finishing the loaded surfaces of machine elements, imparts high quality surface texture and geometry control. The near-net-shape geometry and surface topography of the machine elements must be controlled to be compatible with the network dimensional finish and the rolling die design requirements (Ref. 1).
Plane strain fracture toughness of twelve high-carbon steels has been evaluated to study the influence of alloying elements, carbon content and retained austenite. The steels were especially designed to simulate the carburized case microstructure of commonly used automotive type gear steels. Results show that a small variation in carbon can influence the K IC significantly. The beneficial effect of retained austenite depends both on its amount and distribution. The alloy effect, particularly nickel, becomes significant only after the alloy content exceeds a minimum amount. Small amounts of boron also appear beneficial.