Alloy Steel 4340 Vac Melt

The alloy steel known as 4340 Vac Melt (meaning vacuum melted) is an ultrahigh-strength steel consisting of several elements such as carbon, manganese, and chromium. It is affiliated with a UNS designation of G43406. As one member in a large family of alloy steels, it like its other counterparts were developed so as to serve a variety of industrial purposes. This version is especially used where there are severe service conditions and where heavy sections require high strength. Thin sections harden by air exposure. 4340 Vac Melt itself displays certain characteristics such as high toughness, ductility, and strength while maintaining high resistance to creep and fatigue. Those kind of properties combined together makes 4340 (Vac Melt) a material highly valued for use in a number of engineer - and especially aerospace - applications. This particular steel alloy therefore presents an favorable combination of high strengths and has great potential for applications in a variety of fields.

Alloys of this nature were not always in high demand, and their start came a little later than other metal developments. It was Julius Baur in 1865 who first patented general alloy steels. He was an American metallurgist and the steels were then produced by the Chrome Steel Co. of Brooklyn, New York. However, it was the French metallurgist Henri-Ami Brustlein who subsequently popularized the metal by further developing it. With time, there were more and more needs for a diverse field of alloyed steels. In previous eras, there were not so many large vehicles or transportation in dense circumstances crossing sophisticated infrastructure nor were there large plants and the mass-production of aviation development and aircrafts. As those eras came into the picture, however, inventions that dabbled in the alloying of various metals became critical parts of the advancement of engineering in these fields as well as the continued advancement of the science - and arguably the art as well - of metallurgy. This alloy steel 4340 Vac Melt comes according to a variety of specifications, each serving different niches of the industries choosing to commonly utilize such types of alloys. For this particular alloy, its specifications generally are codified under AMS 6414, AMS 6409, AMS 6415, AMS 6484, AMS-S-5000, DMS 1555 Gr A, BMS 7-28, BPS 299-947-055, SS 9702, PWA LCS F-17, MIL-S-8844 CL1, and MIL-S-5000, as well as others.

Chemistry of Alloy Steel 4340 Vac Melt

The chemical composition of this particular alloy includes Carbon (C), Manganese (Mn), Silicon (Si), Phosphorus (P), Sulfur (S), Chromium (Cr), Nickel (Ni), Molybdenum (Mo), and Copper (Cu). The specifications outlined for percentage by weight of each of these contained elements typically cites the following ratios: Carbon (0.38 0.43%), Manganese (0.65 to 0.90%), Silicon (0.15 to 0.35%), Phosphorus (0.01%), Sulfur (0.01%), Chromium (0.70 to 0.90%), Nickel (1.65 to 2.00%), Molybdenum (0.20 to 0.30%), and Copper (0.35%). 4340 Vac Melt typically has a density of 7.84 g/cm3 (or 0.283 lb/in3). It has a Brinell rated hardness of 217, a 10% elongation at break, a shear modulus of 80 GPa (or 11.6 ksix10^3), and an elastic modulus of 205 GPa (or 29.7 ksix10^3). In addition, this specific alloy has a yield strength of 470 MPa (or 68.2 ksi) and its ultimate tensile strength is about 745 MPa (or 108 ksi) in the annealed condition. It also has a reduction of area of about 30%.

The specifications for this alloy include AMS 6414, AMS 6409, AMS 6415, AMS 6484, AMS-S-5000, DMS 1555 Gr A, BMS 7-28, BPS 299-947-055, SS 9702, PWA LCS F-17, MIL-S-8844 CL1, and MIL-S-5000. This grade of the alloy should be forged between 1950 and 2250 degrees F (or about 1066 to 1232 degrees C). It is recommended that preheating or even furnace cooling is done in lime or ash. For machining this alloy, it should first be normalized and then subsequently tempered at approximately 1200 degrees F (or about 649 degrees C) for optimum results. It can also be welded using arc fusion or gas methods. If air hardening, the material ought to be normalized or annealed and tempered once it has been welded. This alloy is typically used in applications which require its strengths against failure; however, it should be noted that the steel can have poor resistance to stress-corrosion cracking if has been tempered to between 1500 and 1950 MPa (or 220 to 280 ksi). That being said, its fatigue life can also be improved as t is readily nitrided. Any parts that face exposure to hydrogen should be baked immediately afterwards as well. These circumstances would include plating and pickling processes that may occur depending on how the material is to be prepared and subsequently used. Typically oil quenched, this alloy s not as impacted by temper embrittlement as others might be. It also does not readily soften when temperatures are raised, meaning it retains its strength well. Hydrogen embrittlement, however, can cause the material some difficulties in maintaining its structural integrity.

Our Alloy Steel 4340 (Vac Melt) Products

Here at AMC we sell many kinds of alloys that are used frequently in structural components, machining parts, and a number of engine parts and gear components as well. The Federal Aviation Administration (FAA) often oversees numerous regulations that govern specifications for products used in aviation-related parts. The AMC products we have available fall within the AMS specification numbers of 6409 to 6484. For this particular alloy, we offer it in the form of bars, sheets, and plates.