CNC Machining: Stainless Steel and Titanium Difference?
Dec 08, 2022
What is Stainless Steel?
In metallurgy, stainless steel is a category of highly alloyed steel designed to provide high corrosion resistance with at least 10.5% chromium by mass, with or without additional alloying elements, and a maximum of 1.2% carbon by mass. It is steel mixed with one or more elements to modify its properties. Alloying is the process of combining more than one metal.
Stainless steels, commonly known as inox steels or inox from the French inoxydable (inoxidizable), are steel alloys that are very well known for their corrosion resistance that rises with rising chromium content. The chromium in the alloy forms a thin, impervious oxide film in an oxidizing atmosphere, which protects the surface from corrosion. Nickel is another alloying ingredient in certain stainless steel to increase corrosion protection. Carbon is used to strengthen and harden the metal.
In metallurgy, stainless steel is a steel alloy with at least 10.5% chromium with or without other alloying elements and a maximum of 1.2% carbon by mass. Stainless steels, also known as inox steels or inox from French inoxydable (inoxidizable), are steel alloys, which are very well known for their corrosion resistance, which increases with increasing chromium content. Corrosion resistance may also be enhanced by nickel and molybdenum additions. The resistance of these metallic alloys to the chemical effects of corrosive agents is based on passivation. For passivation to occur and remain stable, the Fe-Cr alloy must have a minimum chromium content of about 10.5% by weight, above which passivity can occur and below which it is impossible. Chromium can be used as a hardening element and is frequently used with a toughening element such as nickel to produce superior mechanical properties.
5 Types of Stainless Steel
Stainless Steel can be divided into five different types. These include:
-
Ferritic stainless Steels
-
Austenitic Stainless Steels
-
Martensitic Stainless Steels
-
Duplex Stainless Steels
-
PH Stainless Steels
Ferritic Stainless Steels
Ferritic stainless steels have around 10.5 to 30% chromium, low carbon (C<0.08%), and no nickel. They are referred to as ferritic alloys because they have principally ferritic microstructures at all temperatures and cannot be hardened by heat treatment and quenching. While certain ferritic grades include molybdenum (up to 4.00%), chromium is the major metallic alloying ingredient. Furthermore, they have relatively low high-temperature strength. Ferritic steels are selected for their resistance to stress corrosion cracking, making them an appealing option to substitute austenitic stainless steels in applications of chloride-induced SCC. The AISI 400-series of stainless steels includes a significant number of ferritic steels. Some varieties, like the 430 stainless steel, have great resistance to corrosion and high heat tolerance.
430 Stainless Steel
430 stainless steel is a versatile steel with excellent corrosion resistance. It possesses higher thermal conductivity than austenite, a lower thermal expansion coefficient than austenite, heat fatigue resistance, the inclusion of the stabilizing element titanium, and strong weld mechanical properties. 430 stainless steel is utilized in building ornamentation, fuel burner components, household appliances, and home appliance parts.
430F is a steel grade that adds free-cutting performance to 430 steel. It is primarily used to manufacture automated lathes, bolts, and nuts. 430LX is an alloy in which Ti or Nb is added to 430 steel to reduce C content and improve processing and welding performance and primarily used for hot water tanks, hot water supply systems, sanitary appliances, home appliances, durable appliances, bicycle flywheels, and other applications.
Austenitic Stainless Steels
Austenitic stainless steels have a Cr content ranging from 16 to 25% and can also include nitrogen in the solution, both of which contribute to their relatively strong corrosion resistance. Austenitic stainless steels offer the highest corrosion resistance of any stainless steel, as well as exceptional cryogenic characteristics and high-temperature strength. They have a nonmagnetic face-centered cubic (fcc) microstructure and are readily welded. This austenite crystalline structure is obtained with adequate amounts of the austenite stabilizing elements: nickel, manganese, and nitrogen.
Although austenitic stainless steel cannot be hardened by heat treatment, it can be hardened to high strength levels while preserving desirable ductility and toughness. The most well-known grades of austenitic stainless steel are 304 stainless steel and 316 stainless steel, which offer exceptional resistance to various ambient conditions and numerous corrosive media.
304 Stainless Steel
In austenitic stainless steel, 304 stainless steel is particularly prevalent. It has a high nickel level that ranges between 8 and 10.5% by weight and a high chromium content of between 18 and 20% by weight. Manganese, silicon, and carbon are other important alloying ingredients. The rest of the chemical makeup is mostly iron. Because of the high levels of chromium and nickel, 304 stainless steel has good corrosion resistance. Common uses for 304 stainless steel include refrigerators and dishwashers, commercial food processing equipment, fasteners, piping, heat exchangers, and construction in situations that would corrode conventional carbon steel.
316 Stainless Steel
316 stainless steel, like 304, contains a high concentration of chromium and nickel. 316 also includes silicon, manganese, and carbon, with iron accounting for the bulk of the composition. The chemical makeup of 304 and 316 stainless steels differs significantly, with 316 containing a large quantity of molybdenum; often 2 to 3% by weight vs. merely negligible levels in 304. Because of the higher molybdenum concentration, grade 316 has greater corrosion resistance. Regarding austenitic stainless steel for maritime applications, 316 stainless steel is frequently regarded as one of the best options. 316 stainless steel is also often used in equipment for processing and storing chemicals, refineries, medical devices, and maritime environments, especially those with chlorides.
Martensitic Stainless Steels
Martensitic stainless steels, like ferritic steels, are based on chromium but have a greater carbon content of up to 1%. They have a chromium content of 12 to 14%, a molybdenum content of 0.2 to 1%, and usually no nickel. Because they contain more carbon, they can be hardened and tempered like carbon and low-alloy steels. They have moderate corrosion resistance and are robust, strong, and slightly brittle. In contrast to austenitic stainless steel, they are magnetic, and a non-destructive test utilizing the magnetic particle inspection method can be performed on them. Typical products include cutlery and surgical instruments.
Duplex Stainless Steels
As their name implies, Duplex stainless steels are a mixture of two of the most common alloy kinds. They feature a mixed microstructure of austenite and ferrite to produce a 50/50 blend, while the ratio may be 40/60 in commercial alloys. Their corrosion resistance is comparable to that of austenitic stainless steel. Still, their stress-corrosion resistance (particularly to chloride stress corrosion cracking), tensile strength, and yield strength (about twice that of austenitic stainless steels) are typically greater. Carbon is preserved to a very low level (C<0.03%) in duplex stainless steel. Their chromium level varies from 21.00 to 26.00%. Their nickel content ranges from 3.50 to 8.00%, and molybdenum may be included in these alloys (up to 4.50% ). Toughness and ductility are often intermediate between those of austenitic and ferritic grades.
Based on their ability to resist corrosion, duplex grades are classified into three sub-groups: standard duplex, super-duplex, and lean duplex. Compared to conventional austenitic steels, super-duplex steels offer greater strength and resistance to all types of corrosion. Marine applications, petrochemical plants, desalination plants, heat exchangers, and papermaking are all common usages. The oil and gas sector is the major customer today, and it has pushed for more corrosion-resistant grades, resulting in the wide use of super-duplex steels.
PH Stainless Steels
PH stainless steels (precipitation-hardening stainless steels) contain around 17% chromium and 4% nickel, providing an optimal combination of martensitic and austenitic properties. They are noted for their capacity to develop high strength with heat treatment, similar to martensitic grades, and they also have the corrosion resistance of austenitic stainless steels. Even at high temperatures, these alloys maintain their strength and corrosion resistance, making them good for use in aerospace.
Precipitation-hardening stainless steels have high tensile strengths due to a heat treatment technique that results in precipitation hardening of a martensitic or austenitic matrix. Hardening is accomplished by incorporating one or more elements: copper, aluminum, titanium, niobium, and molybdenum. They typically are the best combination of high strength, toughness, and corrosion resistance of all the available stainless steel grades.
To learn more about Stainless steel technical properties, please check the Stainless Steel Grade Chart – Technical Properties.pdf
What is Titanium?
Titanium is a silver-colored, shiny transition metal with a low density of 4.506 g/cm3 and a melting point of 1,668 ℃. The two most useful properties of titanium are corrosion resistance and the highest strength-to-density ratio against any metal. Titanium is 30 % stronger than steel but nearly 43 % lighter, and 60 % heavier than aluminum but twice as strong.
Titanium has a relatively low thermal expansion coefficient and fairly hardness, although not as hard as some heat-treated steel, is nonmagnetic, does not exhibit a ductile-brittle transition, and has good biocompatibility and a poor conductor of heat and electricity. However, oxygen and nitrogen are absorbed by titanium rapidly at temperatures above 500 ℃, which leads to potential embrittlement problems.
Stainless Steel vs. Titanium: What Are Their Differences?
Titanium and stainless steel are widely employed in various consumer and industrial applications. What is the difference between stainless steel and titanium? Titanium and stainless steel have distinct properties that set them apart from one another. We shall compare titanium and stainless steel, utilizing different properties for ease of comprehension.
Titanium vs Stainless Steel: Color
When it comes to color, titanium and stainless steel may look similar. Titanium and stainless steel in the natural state are silvery metals. The difference is that titanium is somewhat darker. In another dimension, both titanium and stainless steel may look grey, however, titanium will be darker than stainless.
TITANIUM vs STAINLESS STEEL
Lathe - Machining multiple materials on the Doosan SMX3100 Mill Turn. Tyson shows you exactly how to Face, OD Turn and ID Bore in both 316 Stainless and 6AL-4V Titanium. He also shows all parameters and the differences in time.
HYDRAULIC PRESS VS TITANIUM AND STEEL BOLT, WHICH IS STRONGER
We will test the strength of titanium bolts from a spaceship with a hydraulic press. Which bolt is stronger titanium or steel
Comparing the Differences in Roughing
Element Composition
The composition of the elements can be utilized to distinguish titanium from stainless steel. Commercially pure titanium, generally speaking, comprises a range of elements such as nitrogen, hydrogen, oxygen, carbon, iron, and nickel. Titanium is the primary element, with other elements ranging in percentage from 0.013% to 0.5%.
Stainless steel, on the other hand, is made up of various elements, including at least 10.5% chromium and additional elements, with percentage compositions ranging from 0.03% to more than 1.00%. The chromium component in stainless steel aids in corrosion prevention and offers heat resistance. These elements are aluminum, silicon, sulfur, nickel, selenium, molybdenum, nitrogen, titanium, copper, and niobium.
Hardness
A material’s hardness is a comparative measure that defines the material’s response to etching, deformation, scratching, or denting over its surface. This measurement is generally done with indenter machines, which come in multiple types based on the material’s strength. The Brinell hardness test is used by makers and consumers of high-strength materials.
While stainless steel’s Brinell hardness varies widely depending on alloy composition and heat treatment, it is generally tougher than titanium. Titanium, on the other hand, deforms quickly when indented or scraped. To circumvent this, titanium generates an oxide layer known as the titanium oxide layer, which forms an extremely hard surface that resists the most penetrating pressures.
Durability
The capacity of a material to continue to function without requiring excessive repair or maintenance during its half-life is an indicator of the material’s durability. Because of their superior characteristics, titanium and stainless steel are both long-lasting. Titanium is about 3 to 4 times stronger than stainless steel. This allows titanium to have a lifespan that is increased by several generations.
Elasticity
Elasticity is a measure of a material’s flexibility. In other words, it evaluates how easily a material can be bent or warped without distortion. The normal elasticity of stainless steel is 200 GPa, whereas titanium’s is 115 GPa. Because most of its alloys are more elastic, stainless steel often beats titanium in this area. Again, more flexibility makes it easier to mill stainless steel and make different parts. This is an important quality because it directly affects the cost of processing.
Tensile Strength
A material’s ultimate tensile strength is the maximum on the engineering stress-strain curve. It is the greatest stress that a material in tension can withstand. Most of the time, ultimate tensile strength is abbreviated as tensile “strength” or “the ultimate.” Stainless steel has a greater ultimate tensile strength than titanium.
The important point to remember here is that while stainless steel has greater overall strength, titanium has greater strength per unit mass. As a result, stainless steel is often the best choice if overall strength is the major driver of an application selection. If weight is of primary importance, titanium may be a better alternative.
Yield Strength
A material’s yield stress or yield strength is the stress at which it distorts. The yield strength of stainless steel 304L is 210 MPa, compared to 1100 MPa for Ti-6AI-4V (Titanium grade). As seen by the elasticity differential, titanium is harder to produce yet has a higher strength per unit of mass.
Also, titanium is biocompatible, while stainless steel is not. Because of this, titanium is a great choice for a wide range of medical uses.
Weight
One notable distinction between titanium and stainless steel is their weight. Titanium has a high strength-to-weight ratio, allowing it to deliver about the same level of strength as stainless steel at 40% of the weight.
As a result, titanium is essential for applications requiring minimal weight and maximum strength. This is why titanium is useful in airplane components and other weight-sensitive applications. On the other hand, steel is useful for car frames and other things, but it is often hard to make things lighter.
Price
Titanium is more costly than stainless steel in terms of pricing. As a result, titanium becomes more expensive for some industries, like buildings, where huge volumes are required. If cost is a big factor, stainless steel may be better than titanium if both are good enough.
Stainless steel is a reasonably priced option. It is easier to manufacture since there is no scarcity of iron or carbon on earth. Furthermore, there are no sophisticated processing requirements for stainless steel. Stainless steel prices, on the other hand, vary greatly due to the sheer number of options. A carbon and iron alloy would be the least costly. Those constructed from chromium, zinc, or titanium would be more expensive.
Stainless Steel Price vs. Titanium Price
Applications
Stainless steel and titanium have different applications. Stainless steel is ideal for architecture, paper, pulp and biomass conversion, chemical and petrochemical processing, food and beverage, energy, firearms, automobiles, the medical industry, and 3D printing. On the other hand, titanium is perfect for aerospace, consumer applications, jewelry, the medical industry, and nuclear waste storage.
Stainless Steel vs. Titanium: Which One to Choose?
Both stainless steel and titanium have distinct properties that make one or the other more appropriate for your specific needs. Knowing the pros and cons of both metals will assist you in making your decision. Below are their advantages and disadvantages.
Advantages of Stainless Steel
-
Low price and is readily available.
-
High strength and durability.
-
Excellent corrosion resistance.
-
Excellent mechanical properties.
-
Sustainability and environmentally friendly.
-
High strength and superior durability.
-
Stainless steel is recyclable.
-
Easy to customize.
-
Stainless steel equipment is easy to clean.
Disadvantages of Stainless Steel
-
The strength gets lower at high temperatures.
-
Difficult to weld or fabricate.
-
Stainless steel equipment is very heavy.
Advantages of Titanium
-
Amazing corrosion resistance.
-
High-melting point and withstand high temperatures.
-
High strength and lightweight.
-
Non-toxic, widely used in the medical industry.
-
Good biocompatibility.
-
Recyclable.
Disadvantages of Titanium
-
Expensive cost.
-
Low elasticity and is readily deformed.
-
Difficult in extracting, casting, and processing.
In summary
The main distinction between the two materials is that titanium is an element while stainless steel is an alloy. Titanium’s properties occur naturally in the metal. On the other hand, stainless steel is a metal alloy of chromium, iron, nickel, and other things.
Because of these differences, the properties of both metals may differ from each other, making them both viable possibilities. We recommend that you select the one that suits your application best.
Thank you for reading our article. We hope it can help you better understand the differences between titanium and stainless steel so that you can pick the right material for your project.
If you are looking for a component manufacturing supplier, please do not hesitate to contact me!We'd be happy to make you an offer. Thank you
FAQs
Does Titanium Corrode?
No, titanium does not corrode easily.
Does Stainless Steel Rust?
Yes, stainless steel can rust in harsh conditions.
Can Titanium be Machined?
Yes, titanium can be machined. But it is not as easy to work with.
Can Stainless Steel Be Welded?
Yes, stainless steel can be welded. It is a more common choice for cookware because it is easy to weld.
Can Titanium be Tempered
Yes, titanium can be tempered. It has a higher tensile strength than stainless steel.
Is Stainless Steel A Good Conductor of Electricity and Heat?
Yes, stainless steel is a good conductor of electricity and heat. This is why it is often used in cookware. Titanium is not a good conductor of heat, so stainless steel would be a better choice for cookware that needs to heat up quickly.
What Are Some Applications Where Titanium Would Be A Better Choice Than Stainless Steel?
Titanium is often used in medical implants and other applications where welding is not feasible.
If you are looking for a component manufacturing supplier, please do not hesitate to contact me!We'd be happy to make you an offer. Thank you
Reference article:
https://material-properties.org/stainless-steel-vs-titanium-alloy-comparison-pros-and-cons/
