One Minute Mentor: Distortion in Tool Steels

Some of the main interactions  that occur during the heat treatment of steel alloys including temperature, microstructure, and stress/strain. Especially for tool steels these interactions are mainly influenced by the carbon content in the steel matrix, the types and relative amounts of the alloying elements, and the carbide formation/transformation/precipitation characteristics of the alloy system.

Heat treatment involves changes of temperature with time, which determine changes in microstructure. The rate of temperature change results in a change of microstructure which is described by phase transformation kinetics, as in e.g. TTT (time-temperature-transformation) diagrams; every phase transformation releases/absorbs latent heat, which influences the temperature field. An inhomogeneous temperature distribution, i.e. temperature gradients, within the tool during heat treatment can generate thermal stresses that lead to plastic deformation, if the yield strength of the material at that temperature is exceeded. Every mechanical deformation generates heat which, in turn, influences the temperature field. Furthermore, there is an interaction between the stress state and the microstructure. Phase transformations can result in micro-plastic deformation, which can be globally described using transformation plasticity models.

For more information, click on the link below (subscription required). Then scroll to Figure 2. R Schneider; R. Mesquita; W Schützenhöfer, Distortion in Tool Steels, ASM International, 2014  https://doi.org/10.31399/asm.hb.v04d.a0005980

 

Researchers overcome manufacturing challenges in aluminum alloys with nano-treatment

Researchers at the University of California, Los Angeles, have achieved a significant breakthrough in the field of metal additive manufacturing (AM), specifically with Al–Cu alloys like AA2024, which are prevalent in the aerospace and automotive industries. 

These alloys are known for their high strength and good fatigue resistance but have been notoriously difficult to work with in additive manufacturing due to issues like hot cracking and other solidification defects.

The UCLA team has successfully developed a nano-treated AA2024 deposition that incorporates TiC nanoparticles, leading to a groundbreaking enhancement in the manufacturing process. This new method allows for the additive manufacturing of AA2024 without the occurrence of cracks, a common issue that has hindered broader adoption of these materials in high-precision sectors.

Microstructural analysis conducted by the researchers reveals that the TiC nanoparticles not only reduce the susceptibility to hot cracking but also refine and homogenize the grain structure of the alloy. The grains were significantly refined to an average size of 23.2 ± 0.4 μm. This refinement contributes to the material’s enhanced properties, including its mechanical performance.

These findings highlight the potential of nano-treatment techniques in overcoming the longstanding challenges associated with high-strength aluminum in additive manufacturing. This advancement not only paves the way for more reliable production of critical components in aerospace and automotive applications but also promises to expand the capabilities and applications of metal additive manufacturing technology.

Read further here. 

Lindberg/MPH ships rod overbend box furnace to the manufacturing industry

Lindberg/MPH, Mich., has announced the shipment of a rod overbend box furnace with powered load/unload table to the manufacturing industry. This heat-treating furnace has a maximum temperature rating of 2000°F and a load capacity of 900 lbs. 

The workspace dimensions of the furnace are 24” W x 36” D x 18” H and it is designed for air atmosphere applications. The box furnace features an automated actuator to flip the push/pull mechanism on the load table to eliminate the operators need to manually flip it into push position. This option allows the push/pull head to retract from the furnace once the work grid is in the furnace chamber and increase operator safety by removing the need to reach into the hot furnace with a hook to flip the push/pull head and.

The furnace chamber is heated with a radiant heating system the utilizes heavy gauge alloy rod over-bend heating elements mounted along the side-walls and the floor. The furnace temperature is controlled by an Allen Bradley ControlLogix Programmable Logic Controller that includes digital setpoint and display. A Honeywell DC2500 high limit controller disconnects the power to the heating elements and sounds an audible alarm if the temperature exceeds desired set-point. 

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EndoFlex generator chosen for fastener heat treatment

UPC-Marathon, Quebec,, a Nitrex company, has commissioned a 100 M3H EndoFlex endothermic gas generator for a South American manufacturer of industrial fasteners.

This is a repeat customer that has UPC-Marathon‘s gas panels, flowmeters, oxygen probes, and Protherm plant automation software installed in their heat treatment operations. With the addition of the EndoFlex generator, they will now be able to supply gas to a new continuous mesh belt neutral hardening furnace for the treatment of metal fasteners used in automotive applications.

The customer had the option to choose between a nitrogen-methanol system or an endothermic gas generator for their neutral hardening furnace. After careful consideration, they selected UPC-Marathon’s EndoFlex generator in order to achieve better control and consistency of the process atmosphere. The result is an improved hardening process and higher-quality hardened fasteners, along with reduced operating costs. The EndoFlex mixes ratios more accurately and efficiently, ensuring a constant furnace atmosphere and consistent gas quality, leading to immediate cost savings through reduced electricity and gas consumption and zero waste.

The system was started in March 2023, and its consistent performance has exceeded the customer’s expectations.

Read further here.