Technical Memo

Materials for Large Component Design

There wouldn't be an HMC Difference if we didn't offer Advanced Technology Materials for your Critical to Process Replacement Parts!

HMC's Large Mechanical Component Designs are made from Alloy Steels whose carbon contents are modified by our Engineers and Metallurgists based from their many years of experience to decrease the possibility of cracks and other defects and to increase strength and wear resistance, without causing any compromise to the materials mechanical properties or their ability to Deform and Absorb Stress. Our Special Materials Specifications consist of decreased carbon content and modifications to alloy combinations; such as Nickel, Chromium, Vanadium, and Molybdenum. That is why our Gears, Pinions, and other Critical to Process Products always pass the True Test - The Test of Time.

HMC's Special Alloy Steels have tested to 25 foot lb. Impact Values at operating temperatures of - 40 Degrees Fahrenheit..

This is especially achievable through a material we were instrumental in introducing in the early 1980's; 4330 Vanadium Modified. 4330 VM with comparable hardness to 4340 will offer 100% impact values (the ability to deform and absorb stresses).

HMC has over 30 years experience with the Design and Manufacturing of Large Critical to Process Mechanical Components. Our experience has taught us to be very selective with the materials for your hostile shock loading applications.

For example popular alloy materials such as 4140, 4340, and 4350 are very poor selections for large component use because of uncontrolled segregation of the migrating carbon caused by varying solidification, (cooling), rates in large forgings. The below graph illustrates the actual carbon content across a large forging as compared to the nominal carbon content. You will see near the center of the forging, where the carbon level more than doubles due to segregation. Once the local carbon level exceeds approximately 0.7% a condition known as hypereutectoid occurs. This phenomenon causes pockets of brittle carbides to begin forming in the material which leads to microcracking and other defects. Hypereutectoid also invites the producing of poor mechanical properties.

Impact Values - is a methodology developed by metallurgists to measure designate the limits a material has to Deform and Absorb Stress before it Cracks or Breaks.

4330 mod             impact values up to 25 ft-lbs at -40 degrees

4340                     impact values up to 12 ft-lbs at 70 degrees F

4140                     impact values up to 15 ft-lbs at 70 degrees F

Open Gearing and other large critical to process mechanical components intended for heavy loading require design by Experience. HMC has that experience. And our Unsurpassed Warranties speak for themselves.