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October 7, 2015

THE JOURNEY OF REMELTED ALLOYS

 

First stages

When an alloy is heated above its melting point using magnetic or electrical heat sources, a highly pure, reliable, more stable alloy is the result.  These ingots are then hot worked to produce bar, plate, and block. Any of these forms may be heat treated.

Once treated, they may be used where it is essential that the final product’s properties are essential.  Aerospace and defense industries rely on the performance, homogeneity, fracture toughness, and cleanliness of these steels and super alloys. 

Advantages

Improvement of oxide cleanliness is one of the primary advantages of remelted alloys.  The three types of furnaces that make high-performance specialty alloys are: vacuum-induction melting (VIM), electroslag remelting (ESR), and vacuum-arc remelting (VAR)

Double-vacuum melting combines VIM and VAR, to produce high-purity alloys. Aerospace and high-strength steels are usually double-vacuum melted.

Spotting defects

Occasionally, defects do occur in remelted ingots.  “Tree ring patterns” look like light etched rings and usually are indicative of crystal segregation.  These don’t have an effect on the properties of the resulting alloy.

White spots and freckles, however, can be an important factor in the failure of turbine disks for the aerospace industry.  Freckles are dark spots that are typically high in carbide forming elements and “grow” in a downward direction.  White spots are more likely to occur at lower melting rates. They indicate lower alloying elements.  Dirty white spots can reduce LCF life because they lead to crack initiation

Some of these defects can be detected through several, highly accurate testing methods available.  These include metallography, macroscopic inspection, mechanical testing, EB-button testing, and ultrasonic inspection.  Most, if not all, bar is ultrasonically tested.  In this test, nearly the entire volume is inspected. 

Today’s VAR

Closely controlling every part of the remelting process is imperative for clean ingots. There are computer systems for data management and consumable electrodes are continuously weighed. Today, VAR furnaces include control process parameters of remelting rate, arc voltage, etc. and logic control functions. VAR’s high temperatures and low pressure segregate undesirable elements producing a clean alloy with low gas content.  

At Progressive Alloy

Progressive Alloy is a leading supplier of remelted stainless and alloy products to the Aerospace Industry.  Some of the Remelted Alloys we stock include:  15-5PH VAR, 15-5PH ESR, 13-8MO, Cronidur 30®, 13-8 Supertough®, 17-4 ESR, 440c VAR, 4340 VAR, 4330M, 300M, 9310 VAR, 52100 VAR Just to name a few.   We specialize in Round Bar, Plate and Block products which are complemented with Value Added Processing for small incremental needs or LTA Programs. 

CLICK HERE to see our full range of alloys or talk to one of our sales representatives at 800-798-5619 to find out more.

About Progressive Alloy Steels Unlimited, Inc.
Progressive Alloy Steels Unlimited, Inc. located in Hartsville, SC and Las Vegas, NV is a specialty metals service center stocking various hard to find grades of Stainless Steels, Nickel Alloys and Vacuum Melted Alloy Products. The Company's products are used in various industries such as Aerospace, Power Generation, Medical, and Military Applications. Established in 1999, The Company maintains a high focus on Customer Service, On-Time Deliver and Exceptional Quality.

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