Stainless steel was first recognized as a commercial proposition in 1913, by Harry Brearley, a metallurgist in Sheffield, England, after he noticed that certain gun barrels containing around 13% chromium didn’t rust when they were left outside. What he’d discovered was a steel that approximates to what we know today as type 420 stainless, a grade used to make table knives. Commercial production of this material didn’t start until after the first world war, by which time Doctors Strauss and Maurer at Krupp in Germany were busy discovering what we know as the 18-8 stainless steels. Britain started production of these steels in 1923, under license from the Krupp patent.

This represented the beginnings of stainless steel production and the first steps in a long fight against the many corrosive media which were lurking around to eat up anything that was a piece of steel.

The corrosion resistance of stainless steels is due to the presence of an extremely thin protective oxide film, the so-called “passive film” which forms spontaneously on the steel surface when it’s exposed to air or some other gas or liquid which can supply oxygen to the steel surface. In fact, stainless steel is like humans, in that it needs oxygen to survive. This film is transparent and tightly adherent to the steel, and is so thin, probably less than 0.000001” thick, that it is absolutely invisible while in contact with the surface it’s formed on. The film is insoluble in water and in many other liquids, and impermeable to these and to many gasses.  While it remains intact and tightly adherent to the steel surface, there will be protection from corrosive attack. It seems strange that a huge, heavy weight stainless steel forging owes its corrosion durability to a microscopically thin film, but that’s the way it is. And even if the film is broken locally, serious corrosion will not result providing oxygen is present because the film spontaneously repairs.  If the ruptured film is prevented from repairing itself, corrosion of the steel will continue and will result in either pitting or general attack over the steel’s surface. The protective value of the oxide film on stainless steel will increase with its chromium content. If the steel contains significant amounts of other metals such as nickel or molybdenum, the oxides of these metals will also be present in the film and will improve its resistance to certain types of corrosive attack.

Look for additional blogs on this subject within steelforge.com.  All Metals & Forge Group is a manufacturer of stainless steel forgings and seamless rolled rings for industrial uses, including the PH grades.  This allows AMFG to manufacture the widest range of forged shapes for use in the Industries Served listed on steelforge.com.

We live with metals. Everywhere we turn we see metals. Perhaps we wonder at times where these metals come from. Well, originally, they came out of the ground, on occasion quite deep in the ground, as ores. In other words they were mined. Mining is not a simple process.  It takes large, powerful equipment with boring heads, shovels, blades, or buckets with control arms and shafts made of special alloys, many of which are forged.

Corrosion abrasion, also known as abrasive corrosion, corrosion wear, or slurry erosion, is a significant problem in the mining industry. It is a combined process where both corrosion and abrasion occur simultaneously, often leading to more severe damage to metal parts than either process alone. Thus the need for strong, resistant steels to stand up to these conditions, and for fine-grained forgings, made from closely controlled feedstock, to ensure the required mechanical properties, wear resistance, and corrosion resistance. 

Mining equipment is in constant need of repair, maintenance, replacement parts, or upgrades. Metal surfaces coming in contact with rock or earth include buckets on backhoes, excavators, cable shovels, continuous miners, dippers, and bulldozer blades.  Other equipment includes draglines, dredging machines, hard rock mining machines, drillers, earthmovers, and loaders.  Depending on the mining operation, equipment may include tunnel boring machines, micro-tunneling, power shovels, steam shovels, trenchers, and various loaders.

Road or rail tunnel boring uses metal parts that are exposed to severe abrasion. Some tunnel boring equipment uses rings on the cutting face, while others use bits. The surface condition of metal parts and internal properties are critical in meeting the abrasion conditions of the work site geology.

For the many applications in the mining industry, All Metals & Forge Group supplies forgings for rings, gear blanks, step shafts, hybrid shovels, and crushers. AMFG has the know-how to meet the exacting requirements of the mining industry with forgings made from carbon steel and alloy steel. The company delivers parts to OEMS and aftermarket companies to suit their production schedules or repair demands.

Different forging techniques are used to achieve the final form for a metal part. Closed die forging or stamping is used for parts that are exact duplicates and high volume.  Casting can be used for volume production, but is often used for final shapes with various angles or curvatures. However, open die forging can be used for many cast parts to achieve the same end shape but with far superior mechanical properties, often at a similar cost.

Castings may be used for intricate shapes, providing the stresses on the finished casting will not involve too much load bearing. When the molten metal is poured into a mold, three crystalline shapes will form. The area in contact with the mold will form a chill zone of randomly oriented grains. Next there will be columnar grains, oriented perpendicular to the mold walls, and in the center of the casting will be found an equiaxed zone. Cast parts can be produced from a few ounces to several tons.

The origin of a forging is a casting, in this case as an ingot or billet from a steel mill. Ingots are cast in various shapes, square, rectangular, round or polygonal, as required. This is where the similarity ends in terms of chemistry and mechanical properties. Forgings are crafted quite differently to produce parts with more durable properties for their end use.

Castings of whatever shape will be subject to shrinkage upon solidification. There are methods of reducing the amount of shrinkage but the phenomenon will always occur. Shrinkage in low carbon steel, for example, will run to about 4%, that in aluminum to around 7%. Porosity is a common solidification defect in castings, and its presence will cause problems in load-bearing, corrosion, or abrasion applications. 

The grain structure of castings is non-uniform, hence heat treatment will not bring about the predetermined changes in properties noted in material that has been through a hot working process. But casting, in the hands of those who are steeped in it, might produce part shapes unattainable by any other method of production unless extensive finish machining is employed.

Open die forging picks up where casting leaves off, and will refine the different grain structures present in the cast ingot or billet through heating and then pressing of the material.  Open die forging brings about an inherent superior reliability, improved tolerance capabilities and better machinability. There is greater metallurgical soundness and improved mechanical properties imparted into the material. For the most part, forging stock has been preworked to refine the cast structure and remove defects or porosity from the casting process. This produces what is known as directional alignment, or grain flow, giving important directional properties in strength, ductility, toughness, and fatigue strength. Properly developed grain flow in forgings closely follows the outline of the final part. In contrast, bar stock and plate have unidirectional grain flow, and castings have no grain flow or directional strength.

The degree of structural reliability that is achieved in a forging is as good as, if not better than, that obtained from any other metalworking process. Chemical uniformity is achieved by dispersion of alloys that may have a tendency to segregate, as well as dispersion of nonmetallic inclusions (impurities) that might adversely affect performance of a part under load.

All metals can effectively be forged, and subsequently heat treated. The range of properties that may be obtained in forged products covers the entire range of ferrous and nonferrous metals. A forged part may undergo subsequent manufacturing processes, such as heat treating and specialized cooling, carburizing, or finish machining.

Forgings, with their uniform structures, will respond well to any chosen form of heat treatment. As such, a uniform range of required properties may be obtained from this combination of forging and subsequent heat treatment. Machinability itself will benefit from these carefully controlled processes. Forged parts are suitable for welding, machining of course, and for surface conditioning by plating, polishing or painting.

In many cases, the cost difference between casting and open die forgings can be modest with forgings sources from All Metals & Forge Group, an ISO 9001:2015 and AS9100D manufacturer of open die forgins and seamless rolled rings. Forgings generally cost more while presenting greater long-term durability that reduces replacement cost and total cost of manufacturing in machinery that requires replacement parts during maintenance cycles.

Time was when forging was just forging, beating heated metals into shape with the aid of a hammer. The principle is still the same, the methods infinitely more sophisticated. Today we have methods that have evolved to the point where forging can be controlled to produce complex shapes, large forgings, and seamless rolled rings. But the two major forging methods are called closed die and open die. The basic differences between these two methods control the sizes and shapes that they produce.

Typically, closed die forging is used when hundreds or thousands of identical parts are required with lower mechanical properties.  Closed die forging has size limitations because the parts are produced within a mold.  Open die forging is used when part volumes are just one to several hundred, and when significant structural integrity is required.

Forging techniques, although evolved, are still somewhat of an art, and benefit from an expert operator. This applies particularly to open die forging, where there is no complete enclosure of the metal, and repeated hammering and pressing can lead to the production of any desired shape. Open die forging involves two dies, an upper and a lower, that come into contact with the workpiece. As mentioned, the metal is free to flow where it may, and is effectively under the command of the operator. There are really no limits to the dimensions that can be produced by this process.

Grain flow in open die forging follows the shape of the part being forged. Working of the material leads to a final product that is consolidated, in that it has no porosity, has a uniform grain size, and good mechanical properties. 

The open die technique is best used for relatively small quantities, and is good for discs, forged and rolled rings, cylinders, and shafts, although more complex shapes can be achieved through forging expertis. It is also good for the production of oversize parts.

Closed die forging is not a free forging process, rather it is restricted to the shape of the dies. In fact, the process is often referred to as impression die forging, whereby the metal is forced into the die to give the final part its shape. There are repeated hammer blows and the dies, made normally from hot-work tool steels, will serve to produce the required components.

By the very nature of the closed die process, and the significant costs involved in manufacturing the part dies, the process is best used for long production runs.  The work that is put into die manufacture results in an overall ability to create tighter tolerances, and complex parts, hence less machining required. 

Both methods have inherent advantages. Open die forging can produce very large parts that would not be possible from the closed die process. Theoretically the closed die process can produce parts whose dimensional tolerances will surpass those from the open die process. Both processes produce a grain flow and a lack of internal porosity that result in required mechanical properties. 

As a manufacturer of open die forgings and seamless rolled rings, All Metals & Forge Group can produce a wide range of shapes and part sizes in various metals and heat-treated conditions.  Many industries rely on both open die forged parts and closed die forgings for construction of machinery, turbines, drive shafts, fluid ends, xmas tree flanges, rollers, and hundreds of other finish machined components.

by Royce Lowe

In the world of steel manufacturing, precision and quality are paramount. From mining equipment to food processing machines, forged steel parts serve as the backbone of modern infrastructure and industry. However, ensuring that this vital material meets rigorous standards requires more than just raw materials and machinery—it demands a commitment to certification and quality assurance processes.

Certification standards, such as those set forth by the American Society for Testing and Materials (ASTM) and the International Organization for Standardization (ISO), play a pivotal role in guaranteeing the integrity and reliability of steel products. These standards establish criteria for composition, mechanical properties, and performance, providing a blueprint for manufacturers to follow in their production processes.

At the heart of these standards lies the assurance of quality. By adhering to established certification protocols, steel manufacturers can mitigate the risk of defects, inconsistencies, and structural weaknesses in their products. This not only safeguards the reputation of the manufacturer but also ensures the safety and reliability of end-users who rely on steel for critical applications.

ASTM, a globally recognized authority in materials testing and standards development, offers a comprehensive framework for evaluating and certifying steel products. Its rigorous testing procedures assess various properties, including tensile strength, hardness, and ductility, to ascertain compliance with industry benchmarks. Likewise, ISO provides a standardized approach to quality management, facilitating consistency and accountability across the manufacturing process. All Metals & Forge Group has been ISO-registered since 1994.

Beyond regulatory compliance, the pursuit of certification reflects a commitment to excellence and continuous improvement. By subjecting their operations to external scrutiny and validation, steel manufacturers demonstrate a dedication to delivering superior products that meet or exceed customer expectations. This not only fosters trust and confidence in the marketplace but also drives innovation and advancement within the industry.

Furthermore, adherence to certification standards enhances market competitiveness and opens doors to global opportunities. In an increasingly interconnected world, where supply chains span continents and customer demands transcend borders, maintaining internationally recognized quality certifications is essential for accessing new markets and forging strategic partnerships.

However, the importance of certification and quality assurance extends beyond mere compliance with standards—it is a fundamental aspect of corporate responsibility. By prioritizing the safety and reliability of their products, steel manufacturers uphold their duty to society and the environment. They contribute to sustainable development by minimizing waste, reducing emissions, and conserving resources, thereby leaving a positive legacy for future generations.

At All Metals & Forge Group, we understand the role of steel certification and quality assurance in manufacturing cannot be overstated. From ensuring product integrity to fostering innovation and sustainability, certification standards serve as the cornerstone of excellence in the steel industry. By embracing these standards and investing in quality management systems, All Metals & Forge Group not only safeguards our success but also contributes to the resilience and prosperity of our customers around the world.

Let us quote your next forged part. To submit your Request For Quote, CLICK HERE

Not that long after the end of WWII, an American named W. Edwards Deming tried to talk his fellow countrymen into putting quality into their products. This was at a time when the term quality control meant a bunch of inspectors sifting through finished products, large and small, and throwing out the ones that didn’t meet basic requirements. Deming was met with a “Thanks but no thanks” reply, which he neither liked nor understood.

Mr. Deming was the man who developed systems for Total Quality Management and was ultimately responsible for much-improved methods of quality control that could be applied to any company of any size. Having been turned away by his fellow countrymen, he took his idea off to Japan. He worked with Japanese companies for some years, knowing that his systems might not bear fruit in the short term, and it did, in fact, take a decade or more before he decided he’d succeeded in his mission. The man’s name is still revered in Japan’s manufacturing establishment.

Quality is not just about inspecting a finished product; it’s rather about educating the workforce and getting them to take pride in ownership, one unit with another, to produce goods that meet the customer’s requirements. Of course, it’s really all about the customer, and the motivation to supply a quality product or service must be customer-driven. Hence, we must make sure we know exactly what the customer requires. If we’re supplying steel or other alloys to an end-user, for example, we should ask all the right questions. We need to know what sizes and size tolerances, surface finish, hardness, and other mechanical properties, and what industry or company specification standards are required. In fact, we need to know just about everything that will help our customers on their way to their best possible finished product.

Time was when quality was the responsibility of a Quality Control Department, whose mandate was to ensure that sub-standard stuff didn’t reach the customer’s floor. Material rejected against an order could either be scrapped or reapplied against other, less demanding orders. But there were always attendant dollar losses and the necessity for large areas of a plant to be used for rework.

A true quality program requires the participation of every person who “touches” the product, from the salesperson who takes the order, to the forging team, heat treatment team, machining team, and testing team to the loading dock worker who loads the material on a truck. All forging processes within a company, including times, temperatures, reductions, etc., should be standardized according to each customer’s requirements and end use.

Quality pays. It pays the supplier with lower rejects, thus increasing yield and productivity. It pays the customer because they receive material they can use with confidence.  With open die forging and seamless rolled rings, rejects or part failures can lead to expensive machine failures, downhole breakdowns, or even life-threatening disaster.

All Metals & Forge Group takes great pride in maintaining one of the most stringent ISO9001, AS9100 quality systems in the open die forging and seamless rolled ring industry.  It begins with learning the customer’s end use, required forging surface condition, mechanical properties of the specified material and alloy, forged shape, heat treatment, delivery need, and competitive price, coupled with forging soundness proven by ultrasonic testing, and care in packing goods to arrive in pristine condition at the customer’s desired location.  Every step is monitored by the quality system at AMFG and continuously improved.

AMFG performs rough machining to within 3mm of finish dimensions to reduce the CNC cost at the customer’s machine shop for all the forged shapes the company produces.  The rough machine surface condition is 250 RMS so that proper quality testing can be performed on each part – the AMFG standard.  

The company can perform finish machining to within .001 of an inch for final tolerance and 64 or 32 RMS surface finish.  This level of quality and precision is unique in an industry where other company’s parts are often delivered black, as forged, or with a rough machined surface of 500 RMS without the internal or external steps and dimensions to reduce machining costs.

From inquiry to invoice, All Metals & Forge Group quality is managed and not assumed. Whether the need is for one part, an entire project, or a production run, AMFG delivers.

by Royce Lowe

In 2022, wind energy increased by some 265 TWh, or 14%, to reach over 2100 TWh. This represented the second highest growth among renewable power technologies, behind solar PV.  

But to make serious progress towards the Net Zero Emissions by 2050, which is looking to approximately 7,400 TWh of wind electricity generation in 2030, the average annual generation growth rate needs to increase to about 17%. Thus wind capacity will continue to grow, along with all the hardware that goes along with it.

Most wind farms, some 90 percent, are situated onshore. Unlike offshore farms, they are not susceptible to the effects of seawater spray, but they may be attacked by pollution, rain, dust particles, or other environmental or operational stresses. It has been so far proven that for certain components of a wind turbine the use of stainless steel is advantageous. In addition to its corrosion resistance, the alloy can be easily formed and welded, and in most cases easily machined. It is available as forged parts, and as sheet and plate and rounds. It has excellent toughness at ambient and sub-zero temperatures.

Offshore wind farms are surrounded by seawater, thus subject to constant exposure to salt spray. This means that stainless steel is relied upon in many applications, such as fasteners, safety cables, davit cranes, and fittings. The use of stainless steel in both onshore and offshore wind farms greatly extends the lifetime of wind turbines, and minimizes required maintenance. Stainless steel is relatively easy to clean.

Type 304/304L stainless steel might be described as the workhorse of this group of versatile alloys. 

Type 304L, to which most 304 grades are currently manufactured, is made to 0.03% carbon, and if extra strength is required then nitrogen is added. Type 304L is not susceptible to carbide precipitation during service or welding, hence requires no special precautions, as does type 304. Its basic chemistry is 18.0 to 20.0% chromium and 8.0 to 12.0% nickel. Type 304L has good corrosion resistance in moderately reducing or moderately oxidizing environments. As such, this alloy will be resistant to the elements of rain and all the “foreign bodies” that might be floating around in its environment, hence, its suitability for onshore wind turbine parts. Type 304 cannot be hardened by heat treatment, solely by cold working the material.

Stainless grades 15-5PH and 17-4PH are stainless precipitation-hardening steels that show corrosion resistance similar to that of type 304L. The steels show good forgeability, and unlike the austenitic 304 type, these steels may be hardened by solution treatment followed by a low-temperature hardening. Machinability is good, providing the correct hardening temperature is chosen.

Here are the  chemical analyses of these two steels: 

These two precipitation hardening alloys show good strength and machinability. They may be heat treated to a whole range of mechanical properties by control of the hardening temperature following solution annealing.

When operating in more corrosive areas, as in offshore, it requires a material that will better withstand attack from salt water. Although salt water might be said to be nature’s most corrosive medium, in the case of wind turbines it happens mostly in the form of spray. Immersion of steel, any steel, in salt water, will result in destruction. Exposure to spray is less serious, particularly if the steel can be periodically cleaned. It is likely that the turbine components in stainless steel will be hidden, thus partly protected.

Type 316 stainless steel has much better corrosion resistance than the three grades previously mentioned. Its chemical analysis is: carbon – 0.08% max; chromium – 16.0/18.0%; nickel – 10.0/14.0%; molybdenum – 2.0/3.0%. The alloy is often melted to 0.03% carbon, as with 304L, to prevent carbide precipitation during welding or service. It is the molybdenum in type 316 that gives it the added corrosion resistance, as it reduces pitting of the surface during exposure to the chloride ion in seawater. Frequent cleaning during service, where possible, will help to reduce attack.

 On both land and sea, stainless steels, well-chosen and well fabricated, treated and maintained, will give years of service in the generation of electricity.

by Royce Lowe

The United States has always been one of the world leaders in the oil and natural gas business. Still, with the intensity of fracking a couple of decades ago, it became the world’s number one producer of crude oil and natural gas. Fracking, or hydraulic fracturing, is a technique for recovering gas and natural oil from shale rock. Put simply, it involves drilling into the earth and directing a high-pressure mixture of water, sand, and chemicals at a rock layer to release the natural gas inside. A few years ago, it was estimated that of a million or so oil and natural gas wells in the United States, around 70% were drilled and fracked. 

Another business that goes along with fracking is that of making, shaping, and treating the steel and other metals used to fabricate the drill collars, gears, valve bodies, and fracture pumps. There’s an awful lot of liquid involved in a fracking operation, with millions of gallons of water as the major constituent of the liquid feed, topped up by fracking chemicals and what are called proppants, a sand constituent that is there to keep open the fracking cracks formed from initial drilling.  The oil and gas industry is one of the largest consumers of specialty pipe and tube products. These products are used in various applications, such as drilling, production, and oil and gas transportation. 

The steel components used in the overall fracking infrastructure must be strong and resistant to the numerous thuds and shocks they’ll undergo during the drilling, extraction, and storage operations, as well as the abrasion from all the sand floating around. So, which grades of steel are recommended for use in the oil and gas industry?

Grades 4130, 4140, and 4340 are up to the task or performing well in this harsh environment. These are low alloy steels that may be heat treated to the required mechanical properties for their operating environment. They may be easily machined, particularly if heat treated to the spheroidized annealed condition. They are easily welded but should be treated with care. The three grades complement each other as applied to the oil and gas industry. This is the basic chemistry of the respective alloy steels: 

We will note from the carbon contents that type 4140, for a given heat treatment procedure, will 

produce a harder, stronger material than type 4130. Type 4340, a nickel-bearing steel, will produce the strongest material of the three. It will also hold its strength to around 600 degrees Fahrenheit. It is tough and will hold its toughness to sub-zero temperatures. The hardenability of type 4340 – the ability to be hardened to depth within the steel – is far greater than that of both 4140 and 4130.

Forged components are indispensable in the oil and gas industry thanks to their ability to withstand high pressure, low temperature, and corrosive environments. Key applications include forged flanges that provide secure and leak-proof connections in pipelines, valves, and pressure vessels. Pipelines for transportation would typically be made from 4130 grade, a somewhat less expensive material than 4340 but suitable for the application.

Forged components in the grades listed above will require heat treatment to specified strength and toughness levels. This requires detailed knowledge, garnered over years of experience, of the specific treatments required to obtain desired properties. The treatments may be annealing for optimum machinability or hardening and tempering to give the required strength and toughness levels. 

In the event that the forged parts may exhibit non-uniform deformation throughout a part – because of a complicated shape – a normalizing treatment will be called for prior to undertaking hardening and tempering. It should be noted that the knowledge and experience of the people responsible for heat treatment are a very important part of this operation, as are those responsible for the forging, where forging temperatures and proper reductions come largely from past experience.

The three grades noted above, 4130, 4140 and 4340, will combine to form the necessary infrastructure for a fracking well. The cost of 4340 material will be significantly higher than that of the other two grades. These three steels, forged, heat treated, machined and welded, will all do their part in bringing oil and natural gas to industry and homes.

All Metals & Forge Group stocks raw material in these grades, so it can provide rough machined forgings in 8 to 10 weeks to fulfill your order. Contact one of our Forging Specialists at (973) 276-5000 or sales@steelforge.com.