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Atlas Steam TreatmentAnswer: Steam treatment is a thermal process that creates a thin controlled oxide layer on the surface of an iron based metal component.  Steam treatment can provide a component with increased corrosion resistance, hardness, density and magnetic properties.  It can also be used to seal the porosity and improve its wear characteristic. 

Steam treatment is a batch process with minimal inputs and has been proven to be a cost effective solution for many applications.  Components transferred to steam treat must be kept clean and dry as it is necessary to avoid contaminants or residue on or in the structure prior to processing because it will impact of how well the oxide layer forms on the surface.

As in most thermal treatments, time, temperature and atmosphere are controlled to provide the optimal conditions for the expected finish.  The desired properties of the component will dictate what time and process parameters are used for a given part. During a typical steam treatment process, parts are placed in a steam treat unit and heated to approximately 1000° F.  Once the component is at temperature, steam is introduced and the water vapor reacts with the iron to form the oxide layer (magnetite - Fe3O4).  After a designated period of time the component is removed from the unit and allowed to cool. The oxide appears on the component surface as a blue/black finish.

For several years, employees of Atlas Pressed Metals and their family members participate in the annual March of Dimes, Clearfield County chapter, walk. Throughout the year, the team raises funds to support the cause, this year raising over $2200, enough for second place for funds raised. Atlas Pressed Metals provides a contribution to March of Dimes for each employee who participates. Employees also designed their own t-shirts this year.

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Front Row: Samuel Walburn, infant grandson of Teri Walburn. First row: Corey Walburn, Carrie Dunworth, Debra Walburn, Jordon Walburn, Laura Bergman.
Back Row: Erica Jackson, Teri Walburn, Laken Walburn, Trish Davis, Billy Davis.

Answer: Yes

Since powdered metal components are porous, the absorption of contaminants into PM parts poses a difficulty as well as a flame hazard for welding. Preventing contaminants from being absorbed into the part is critical in weld applications.

Simple Test to Identify the Presence of Porosity Contaminants in PM Parts

  • Atlas uses a hot plate test that is also commonly used by our platers, which will show if there are contaminants in the part. This test consists of heating the hot plate to between 150°-350°F and placing the part on the hot plate. A "smoking" part is a tell-tale sign. The temperature at which the contaminant vaporizes varies based on the substance. Further, if a beaker is placed over the part during the hot plate test, the vapor will condensate on the inside of the beaker, allowing for further testing of the substance.

Answer: Yes

Best Practices for Welding Sintered Metals

  • Keep parts free of contaminants 
    • Residual lubricants, coolants or cleaning solutions reduce the weld integrity.
  • Select a material with a lower carbon content 
    • The materials with a 0.0 - 0.5% perform better than the higher carbon blends.
  • Use a higher density 
    • Parts with densities above 6.8 g/cc provide improved weld contact areas.

PM Welding

Answer:

At lower densities, part porosity is more skeletal in nature, and would enable liquids, such as oil, to pass through the part. However, as part density increases, those “pathways” are reduced or eliminated.

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