Up in smoke

Characterisation and modelling of tempering during multi-pass welding

Surface layer modification charts for gear grinding

An aspect of the present disclosure is directed to low-alloy steels exhibiting high hardness and an advantageous level of multi-hit ballistic resistance with low or no crack propagation imparting a level of ballistic performance suitable for military armor applications. Various embodiments of the steels according to the present disclosure have hardness in excess of 550 BHN and demonstrate a high level of ballistic penetration resistance relative to conventional military specifications.

High hardness, high toughness iron-base alloys and methods for making same

An asynchronous dual-frequency induction heating process for bevel gears

The results of the stress relieving and tempering processes are dependent on the temperature and time of the process, which may be correlated using a parameter such as Holloman's (Holloman-Jaffe) parameter or the Larsen-Miller parameter. These parameters are a measure of the thermal effect of the process on the metallurgical transformation of the steel during tempering. The processes that exhibit the same tempering parameter are expected to exhibit the same effect (such as hardness). However, these more traditional numerical expressions assume isothermal tempering processes which seldom exist in production tempering ovens due to the heat-up period prior to soaking

A historical overview of steel tempering parameters

Numerical Investigation of Asynchronous Dual-frequency Induction Hardening of Spur Gear

Vegetable oils are currently used for biodegradable and renewable base stocks for quenchant formulation. However, there are relatively few references relating to their true equivalency, or lack thereof, comparative to the quenching performance of petroleum oil-based quenchant formulations. To obtain an overview of the variability vegetable oil quenching performance, the cooling curves and rewetting properties were determined, and the surface heat flux properties were calculated. The vegetable oils that were studied included canola, coconut, corn, cottonseed, palm, peanut, soybean, and sunflower oils. Cooling curves were obtained using the Tensi multiple-surface thermocouple 15 mm diameter by 45 mm cylindrical Inconel 600 probe (Note: The multiple thermocouple probe was custom manufactured to conform to a drawing provided by: Heattec located at Seglaregatan 1C, 302 90 Halmstad, Sweden). For comparison, similar data was obtained with Houghto-Quench H100, a conventional (slow) petroleum quenchant oil, and Houghto-Quench HKM, an accelerated (fast) petroleum oil quenchant (Houghton International Inc., Valley Forge, PA). The results of this work will be discussed here.

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Quenchant Cooling Curves, Rewetting, and Surface Heat Flux Properties of Vegetable Oils

The heat treating of metals is a very complicated process in which multiple physical variables nonlinearly couple with each other. The heat transfer at gas–solid and liquid–solid interfaces is the most important problem to be solved in the numerical simulation of heat treatment, which is also the basis for the process design and equipment design of heat treatment. The traditional way in which one takes the parts as investigation objects and sets the heat transfer coefficient on the interface directly inevitably brings significant inaccuracy to simulation results. A series of research achievements in fluid mechanics and heat transfer theory have provided effective ways of dealing with this problem in heat treatment modeling. In this paper, a heat treatment model with an expanded solution domain is proposed after a brief summary of related research results for coupled heat transfer. In this model, the solution domain has been expanded to the surroundings of the heat treating parts. Taking the heating process in an industry furnace as an example, not only the parts and fixture but also the furnace body, furnace chamber, heating units, and all other components in the furnace are modeled as a whole. The virtual equipment design for a novel bell-type gas nitriding furnace has been successfully fulfilled based on the heat treatment simulation and demonstrates the giant advantage of this new model. It is necessary to emphasize that as an important step in the numerical simulation of heat treatment, this new model is far from mature, and a series of key problems still remain.

Jianfeng Gu

Papers

A historical overview of steel tempering parameters

Numerical Investigation of Asynchronous Dual-frequency Induction Hardening of Spur Gear

Quenchant Cooling Curves, Rewetting, and Surface Heat Flux Properties of Vegetable Oils

Numerical Simulation of Heat Treatment Based on the Model With Expanded Solution Domain