All Metals & Forge Group produces the kind of steel components that go into fighter jets and nuclear power plants, and now every single open-die forged part gets an internal scan before it can ship.
Every Steel Part This Fairfield Company Forges Gets an Ultrasound Before It Ever Leaves the Building
All Metals & Forge Group produces the kind of steel components that go into fighter jets and nuclear power plants, and now every single open-die forged part gets an internal scan before it can ship.
AMFG’s open-die forgings and seamless rolled rings made from carbon, stainless, alloy, aluminum, titanium, copper, and nickel are performed in-house in its 50+ year operation in Fairfield, NJ. The company specializes in heavy industrial steel, the kind that needs to withstand decades of extreme physical stresses before seeing retirement.
The kinds of parts that actually get made are things like seamless rolled rings, produced to diameters of up to 50 feet and custom-contoured rings, plus shafts, blocks and discs, and other forged elements machined to near-net-shape before shipping.
As standard practice, every single part that leaves the facility is at minimum rough-machined to near-net shape and can also get heat-treated and finish-machined to exact mechanical tolerances upon request. For the kinds of industries that AMFG’s parts typically cater to, having this level of flexibility is an absolute necessity. When it comes to aerospace and defense, oil and gas refining, power generation, and wind energy, among others, the ability to finish-machine a part to exact specifications is a baseline requirement to get in the door.
ASTM A388 is an ultrasound test for forgings. By directing high-frequency sound waves at the metal, certified inspectors listen for how they reflect off any internal imperfections. Since steel that is forged under pressure is most likely to crack along a void or pocket of improperly consolidated material, these flaws are a showstopper for any part that is to be used in the harshest environments.
By now, AMFG made this non-destructive testing method standard practice for every open-die forging it produces, with qualified personnel conducting the required pulse-echo examinations as specified in the ASTM A388 standard, rather than relying on a third-party inspection vendor.
Voids and Porosity
Pockets of gas that failed to escape the metal during casting or forging.
Internal Cracks
Typically located where stress from thermal gradients failed the metal surface.
Inclusions
Particles or other foreign matter present within the metal volume.
The way an ultrasonic test works, per the standard, is by using a contact pulse-echo setup to send sound waves through the material and listen for imperfections based on the way they bounce back.
Looks for flaws perpendicular to the surface being inspected. As the sound waves go straight down into the metal, their reflections reveal information about the interior structure.
Directs sound waves at around 45 degrees at the flaw location, and is standard whenever the geometry of the part being tested prevents straight access to its surface. This is the case for seamless rolled rings, whose internal flaws are best accessed at an angle.
A forging that passed the ultrasonic test still needs to comply with the requirements set out in the individual contract specifications for the part. The equipment needed for the standard has specific frequency ranges, between 1 and 5 MHz, with 0.4 MHz specified for specialized austenitic stainless steels. The reason behind this is that these steels typically have large grain structures that need lower frequencies to properly transmit sound.
What few people know about the standard that AMFG now applies to every part is that there is no inherent pass or fail criteria for the tests it specifies. A void or inconsistency found in a forging could be well within tolerance for some applications but unacceptable for others. Rather than dictating a universal set of allowable flaws, the standard focuses on describing the exact test procedures for identifying issues. It is up to the manufacturer, in consultation with the buyer, to establish what does and does not constitute an acceptable flaw for a given part or application.
This nuance in the standard is actually what makes it such an important requirement for AMFG’s forging operations. By applying ASTM A388 to every part, rather than on an ad hoc basis for specific buyers, the company signals its commitment to producing parts that meet the demands of the most exacting industries. When it comes to its defense industry, aerospace, and energy clients, such requirements are frequently necessary to meet regulatory requirements, but they also represent a baseline level of quality that makes a part fit for purpose. In essence, the standard itself establishes a common set of definitions, allowing buyers from different industries to interpret test results in the context of their particular application.
