Which is stronger stainless steel or carbon steel?
Stainless Steel is stronger, but not as strong as TMT Steel. … Carbon steel makes up the largest part of steel production and is used in a vast range of applications. Typically carbon steels are stiff and strong. Steel is less malleable and harder than mild steel.
Steel pipes are used as construction piling, to support the weight of heavy buildings when the soil is too weak. It’s also used on the building itself and even its architectural design. Steel pipes are also used to construct ships, the ship yard where they’re kept, oil refineries and even space stations.Steel pipes are used as construction piling, to support the weight of heavy buildings when the soil is too weak. It’s also used on the building itself and even its architectural design. Steel pipes are also used to construct ships, the ship yard where they’re kept, oil refineries and even space stations.
It is an alloy made from Iron and Carbon. There are over 3,500 different types of steel,which can be separated into four groups depending on its chemical content or metal alloy contents.
Steel is an alloy but it is the level of impurities and elements such as nickel, magnesium, molybdenum, silicon, copper, vanadium that helps to determine the grade of each steel.
1. Carbon Steel
- Carbon steels contain Iron, Carbon, and other alloying elements such as Manganese, Silicon, and Copper.
- Carbon is, however, the main alloying constituent of carbon steels, which account for approximately 90 percent of all steel productions.
- Carbon is the hardest element, which is why carbon steel products are also very hard. Varying the percentage of carbon produces steel with different qualities. However, higher carbon content often translates to stronger yet more brittle steel.
- Depending on the level of carbon content, carbon steels can be classified into the following groups:
- Mild or Low Carbon Steels, contain up to 0.32 %C
- Medium Carbon Steels, containing 0.30-0.59 %C
High Carbon Steels, known to contain over 0.6-0.99 %C - Ultra-high Carbon Steels that usually contain about 1.0–2.0 %C
- Also known as Wrought Iron, low carbon steel is the commonest and most cost effective form. It is easy to work, making it suitable for decorative products like lamp posts and fencing.
- As one of the stronger variants, medium carbon steel is often used to forge large structural applications and automotive components while high-carbon steel is mostly used for high-strength wires and springs.
- Also known as Cast Iron, ultra-high carbon steel is the hardest form of them all and often used for knives, axles, punches and other special purposes. Since carbon steels do not contain chromium, they tend to corrode faster than almost every other type of steels.
2. Alloy Steels
- Alloy steels contain common alloy metals in varying proportions, which makes this type of steel suitable for specific applications.
- These alloy metals include aluminum, manganese, nickel, titanium, silicon, copper, and chromium, the addition of which produces properties that are different from those found in regular carbon steels.
- When added, alloying elements can change properties like strength, ductility, formability, hardenability, and ability to resist corrosion.
- For instance, stainless steel is produced by adding chromium and nickel whereas the addition of aluminum results in a more uniform appearance.
- On the other hand, the addition of manganese is known to make steel extremely hard and strong.
- Alloy steels can have diverse mechanical properties due to the broad range of compositions possible.Because of these properties, alloys steels serve a broad range of applications including the manufacture of pipelines, transformers, auto parts, electric motors and power generators.
3. Tool Steels
- This type of steel is alloyed at very high temperatures and often contains hard metals like tungsten, cobalt, molybdenum and vanadium. Since they are not only heat resistant but also durable, tool steels are often used for cutting and drilling equipment.
- Even so, there are various types of tools steels, each containing varying quantities of different alloy metals. As a result, each type of tool steel offers a different level of heat resistance and durability.
4. Stainless Steels
Although stainless steels comprise of several metal alloys, they usually contain 10-20 percent chromium, making it the primary alloying element. Compared to the other forms of steel, stainless steels are approximately 200 times more resistant to rusting, especially the types that contain at least 11 percent chromium. As a result, stainless steel is highly valued for its ability to resist corrosion. Based on their crystalline structure, stainless steels fall into one of the following categories:
Austenitic steels
- Although austenitic steels contain trace amounts of nickel (eight percent) and carbon (0.08 percent), they are high in chromium. In general, austenitic steels have a chromium content of about 18 percent.
- With applications like the manufacture of pipes, kitchen utensils, and food processing equipment, austenitic steels are the most commonly used type of stainless steel. Even though austenitic steels are not responsive to heat treatments, they are valued for their non-magnetic properties.
Ferritic steels
- Apart from containing trace amounts of nickel, less than 0.1 percent carbon, and about 12-17 percent chromium, ferritic steels usually contain alloy metals like molybdenum, aluminum or titanium in small quantities.
- Ferritic steels are magnetic, tough, and very strong. However, cold working can be used to strengthen them further. Unfortunately, they are not responsive to heat treatment, meaning no heating technique can be used to harden them.
Martensitic steels
- In addition to containing moderate amounts of carbon (about 1.2 percent) and nickel (less than 0.4 percent), martensitic steels contain 11-17 percent chromium.
- Aside from having magnetic properties, martensitic steels are also responsive to heat treatments. This type is mainly used to make dental and surgical equipment, blades, knives, and several other cutting tools.
Stainless Steels have the ability to withstand most of the wear and tear caused by everyday use, making them highly durable. Additionally, an invisible layer of chromium serves to prevent oxidation, making stainless steels resistant to scratches and corrosion.
Steel grades standards by country
- For alloys in general (including steel), unified numbering system (UNS) of ASTM International and the Society of Automotive Engineers (SAE).
- American steel grades : AISI/SAE steel grades standard
- British Standards
- International Organization for Standardization ISO/TS 4949:2003
- European standards – EN 10027
- Japanese steel grades : Japanese Industrial Standards (JIS) standard and NK standard
- Germany steel grades : DIN standard
- China steel grades : GB standard
- Czech steel grades : ČSN standard
- Russia steel grades : GOST standard
- Spain steel grades : UNE standard
- France steel grades : AFNOR standard
- Italy steel grades : UNI standard
- Sweden steel grades : SIS standard
- Norway steel grades : DNV standard
Note that an increasing number of national European standards (DIN, AFNOR, UNE, UNI, etc.) and UK standards are being withdrawn and replaced by European Standards (EN). This task is carried out by the Comité Européen de Normalisation (CEN) (European Committee for Standardization).
European standard steel grades
European standard steel grade names fall into two categories:
Steel specified by purpose of use and mechanical properties.
Steel specified by chemical composition.
The inclusion of a letter ‘G’ before the code indicates the steel is specified in the form of a casting.
Category 1
Basic grade designations for category 1 steels consist of a single letter (designating application) then a number signifying the mechanical property (often yield strength) dictated in the standard for that application designation. For some application designations another letter is included before the property value, this number is used to indicate any special requirements or conditions. These additional letters and values depend entirely on the application of the steel and are specified in the standard and far too numerous to mention here.
The next set of 3 digits gives the steel’s minimum yield strength. So S355 has a minimum yield strength of 355 MPa for the smallest thickness range covered by the relevant standard – i.e. EN10025.
Below is a table indicating the most common application codes.
| Application symbol | Meaning | Mechanical Property | Details |
|---|---|---|---|
| S | Structural steel | Minimum Yield Strength | |
| P | Steel for pressure lines and vessels | Minimum Yield Strength | |
| L | Steel for pipe and tube | Minimum Yield Strength | |
| E | Engineering steels | Minimum Yield Strength | |
| B | Steel for reinforced concrete | Characteristic Yield Case | |
| R | Steel for rail use | Minimum Yield Case | |
| H | High Tensile Strength Flat products | Minimum Yield Case | If followed by T then the given mechanical property is minimum tensile strength |
| D | Flat Products for Cold Forming | Followed by C, D or X and two numbers characterising steel | |
| T | Tinmill Products | Nominal Yield Case | |
| M | Electrical Steel | Number = 100 × specific loss in W/kg Number = 100 × nom thick in mm Letter for type of product (A, K, P or S[3]) |
Additional symbols
In addition to the above category codes there are symbols that can be added to the grade code to identify any additional compositional requirements, delivery conditions, mechanical properties, &c. These values depend solely on the type/application code given in the first part of the code and are so numerous as to be impossible to indicate here. Additional symbols are separated from the main code by the plus sign (+).
The most common additional symbols are the impact and temperature codes for structural steels, category 1 – Sxxx.
| Impact Resistance | Temperature | ||
|---|---|---|---|
| Impact code | Testing strength | Temperature code | Testing temperature |
| J | 27 J | R | Room temperature |
| K | 40 J | O | 0 °C |
| L | 60 J | 2 | -20 °C |
| 3 | -30 °C | ||
| 4 | -40 °C | ||
| 5 | -50 °C | ||
| 6 | -60 °C | ||
Delivery condition codes are also relatively common, the most common being:
| Code | Condition |
|---|---|
| A | Annealed |
| QT | Quenched and tempered |
| N | Normalised |
| SR | Stress relieved |
| C | Cold worked |
| U | Untreated |
Electrical steel type of product letters (bold are most recent version 2016):
| Code | Maximum specific loss expressed for magnetic induction | Type of product |
|---|---|---|
| A | 1.5T @50Hz | non oriented |
| D (formerly B) | “ | non-alloy semi-finished (not finally annealed) |
| E | “ | alloy semi-finished (not finally annealed) |
| K (=D+E) | “ | non-alloy and alloy electrical steel sheet/strip in the semi-processed state |
| N | “ | for normal grain oriented products |
| P | 1.7T @50Hz | high permeability grain oriented |
| S | “ | conventional grain oriented |
European standard steel number
In addition to the descriptive steel grade naming system indicated above, within EN 10027-2 is defined a system for creating unique steel grade numbers. While less descriptive and intuitive than the grand names they are easier to tabulate and use in data processing applications.
The number is in the following format: x.yyzz(zz)
Where x is the material type (only 1 is specified so far), yy is the steel group number (specified in EN10027-2) and zz(zz) is a sequential number designated by the certifying body, the number in brackets being unused but reserved for later use.
The steel groups are indicated below:
The steel groups are indicated below:
| Code | Type |
|---|---|
| Non-alloy steels | |
| 00 & 90 | Basic steels |
| 0x & 9x | Quality steels |
| 1x | Special steels |
| Alloy steels | |
| 2x | Tool steels |
| 3x | Miscellaneous steels |
| 4x | Stainless and heat resistant steels |
| 5x – 8x | Structural, pressure vessel and engineering steels |
| 08 & 98 | Special physical properties |
| 09 & 99 | Other purpose steels |
The current certification body is the VDEh in Düsseldorf, Germany.
Comparisons
Below is a table comparing steel grades from different grading systems.
Comparison of steel grades by chemistry
| EN steel number (Europe) | EN steel name (Europe) | ASTM grade (USA) | AISI/SAE grade (USA) | UNS (USA) | DIN (Germany) | BS (UK) | UNI (Italy) | JIS (Japan) |
|---|---|---|---|---|---|---|---|---|
| Carbon steels | ||||||||
| 1.1141 1.0401 1.0453 | C15D C18D | 1010 1018 | CK15 C15 C16.8 | 040A15 080M15 080A15 EN3B | C15 C16 1C15 | S12C S15 S15CK S15C | ||
| 1.0503 1.1191 1.1193 1.1194 | C45 | 1045 | C45 CK45 CF45 CQ45 | 060A47 080A46 080M46 | C45 1C45 C46 C43 | S45C S48C | ||
| 1.0726 1.0727 | 35S20 45S20 | 1140/1146 | 35S20 45S20 | 212M40 En8M | ||||
| 1.0715 1.0736 | 11SMn37 | 1215 | 9SMn28 9SMn36 | 230M07 En1A | CF9SMn28 CF9SMn36 | SUM 25 SUM 22 | ||
| 1.0718 1.0737 | 11SMnPb30 11SMnPb37 | 12L14 | 9SMnPb28 9SMnPb36 | 230M07 Leaded En1B Leaded | CF9SMnPb29 CF9SMnPb36 | SUM 22 SUM 23 SUM 24 | ||
| Alloy steels | ||||||||
| 1.7218 | 4130 | 25CrMo4 GS-25CrMo4 | 708A30 CDS110 | 25CrMo4 (KB) 30CrMo4 | SCM 420 SCM 430 SCCrM1 | |||
| 1.7223 1.7225 1.7227 1.3563 | 42CrMo4 | 4140/4142 | 41CrMo4 42CrMo4 42CrMoS4 43CrMo4 | 708M40 708A42 709M40 En19 En19C | 41CrMo4 38CrMo4 (KB) G40 CrMo4 42CrMo4 | SCM 440 SCM 440H SNB 7 SCM 4M SCM 4 | ||
| 1.6582 1.6562 | 34CrNiMo6 | 4340 | 34CrNiMo6 40NiCrMo8-4 | 817M40 En24 | 35NiCrMo6 (KB) 40NiCrMo7 (KB) | SNCM 447 SNB24-1-5 | ||
| 1.6543 1.6523 | 20NiCrMo2-2 | 8620 | 21NiCrMo22 21NiCrMo2 | 805A20 805M20 | 20NiCrMo2 | SNCM 200 (H) | ||
| 1.5415 | 16Mo3 | A240 A/B/C | K12822 K12320 K12020 K11820 | 15Mo3 | 1503-243B 240 243 | 15Mo3 16Mo3 | STBA12 | |
| Stainless steels | ||||||||
| 1.4310 | X10CrNi18-8 | 301 | S30100 | |||||
| 1.4318 | X2CrNiN18-7 | 301LN | ||||||
| 1.4305 | X8CrNiS18-9 | 303 | S30300 | X10CrNiS18-9 | 303S 31 En58M | X10CrNiS18-09 | SUS 303 | |
| 1.4301 | X2CrNi19-11 X2CrNi18-10 | 304 | S30400 | X5CrNi18-9 X5CrNi18-10 XCrNi19-9 | 304S 15 304S 16 304S 18 304S 25 En58E | X5CrNi18-10 | SUS 304 SUS 304-CSP | |
| 1.4306 | X2CrNi19-11 | 304L | S30403 | 304S 11 | SUS304L | |||
| 1.4311 | X2CrNiN18-10 | 304LN | S30453 | |||||
| 1.4948[citation needed] | X6CrNi18-11 | 304H | S30409 | |||||
| 1.4303[citation needed] | X5CrNi18-12 | 305 | S30500 | |||||
| 1.4401 1.4436 | X5CrNiMo17-12-2 X5CrNiMo18-14-3 | 316 | S31600 | X5CrNiMo17 12 2 X5CrNiMo17 13 3 X5CrNiMo 19 11 X5CrNiMo 18 11 | 316S 29 316S 31 316S 33 En58J | X5CrNiMo17 12 X5CrNiMo17 13 X8CrNiMo17 13 | SUS 316 SUS316TP | |
| 1.4404 | X2CrNiMo17-12-2 | 316L | S31603 | 316S 11 | SUS316L | |||
| 1.4406 1.4429 | X2CrNiMoN17-12-2 X2CrNiMoN17-13-3 | 316LN | S31653 | |||||
| 1.4571 | 316Ti | S31635 | X6CrNiMoTi17-12 | 320S 33 | ||||
| 1.4438 | X2CrNiMo18-15-4 | 317L | S31703 | |||||
| 1.4541 | 321 | S32100 | X6CrNiTi18-10 | 321S 31 | SUS321 | |||
| 1.4848 | GX40CrNiSi25-20 | A351 HK40 | J94204 | SEW 595 GX40CrNiSi25-20 | 310C40 | SCH22 | ||
| 1.4859 | GX10NiCrSiNb32-20 | N08151 | GX10NiCrSiNb32-20 | |||||
| 1.4878,[citation needed] | X12CrNiTi18-9 X8CrNiTi18-10 | 321H | S32109 | |||||
| 1.4906 | X7CrNiNb18-10 | 347H | S34709 | |||||
| 1.4512[citation needed] | X6CrTi12 | 409 | S40900 | SUH409 | ||||
| 410 | S41000 | |||||||
| 1.4016 | 430 | S43000 | X6Cr17 | 430S 17 | SUS430 | |||
| 440A | S44002 | |||||||
| 1.4112[citation needed] | 440B | S44003 | ||||||
| 1.4125[citation needed] | 440C | S44004 | X105CrMo17 | SUS440C | ||||
| 1.4104 | 430F | S44020 | X14CrMoS17 | SUS430F | ||||
| 1.4057 | X17CrNi16-2 | 431 X | S43100 | X16CrNi16 | 431S 29 | SUS431 | ||
| 1.5423 | 16Mo5 | A335 P1 | 4520 4419H 4419 | K11522 | 16Mo5 | STPA12 | ||
| 1.7715 | 14MoV6-3 | A335 P2 | K11547 | 14MoV6-3 | 660 | STPA20 | ||
| 1.7335 1.7338 | 13CrMo4-5 10CrMo5-5 | A335 P11 | K11597 | STPA23 | ||||
| 1.7375 1.7380 1.7383 | 10CrMo9-10 11CrMo9-10 12CrMo9-10 | A335 P22 | K21590 | 17175 10CrMo910 | STPA24 | |||
| 1.7362 1.7366 | X11CrMo5 X12CrMo5 12CrMo19-5 | A335 P5 | 501 502 | K41545 S50100 S50200 | STPA25 | |||
| 1.7386 | X11CrMo9-1 X12CrMo9-1 | A335 P9 | 503 | S50400 S50488 K90941 | STPA26 | |||
| 1.4903 | X10CrMoVNbN9-1 | A335 P91 | K91560 | X10CrMoVNbN9-1 | ||||
| 1.4905 1.4906 | X11CrMoWVNb9-1-1 X12CrMoWVNbN10-1-1 | A335 P92 | K92460 | X11CrMoWVNb9-1-1 X12CrMoWVNbN10-1-1 | ||||
| 1.4539 | X1NiCrMoCu25-20-5 | 904L | N08904 | |||||
| 1.4547 | X1CrNiMoCuN20-18-7 | S31254 | ||||||
| 1.4565 | NIT50 | S20910 | ||||||
| NIT60 | S21800 | |||||||
| Tool steels | ||||||||
| 1.2363 | X100CrMoV5 | A-2 | T30102 | X100CrMoV51 | BA 2 | X100CrMoV5-1 KU | SKD 12 | |
| A-3 | T30103 | |||||||
| A-4 | T30104 | |||||||
| A-6 | T30106 | |||||||
| A-7 | T30107 | |||||||
| A-8 | T3010 | |||||||
| A-9 | T30109 | |||||||
| 1.2365 | X32CrMoV3-3 32CrMoV12-28 | H10 | T20810 | X32CrMoV3-3 32CrMoV12-28 | SKD 7 | |||
| 1.2379 | X153CrMoV12 | D-2 | X153CrMoV12-1 | BD 2 | X155CrVMo12-1 | SKD 11 | ||
| 1.2510 | O-1 | 100MnCrW4 | Bo 1 | 95MnWCr-5 KU | ||||
American Petroleum Institute (API) steel grades
Color coding
In order to clearly distinguish the steel grade, tubing, casing and its coupling should be painted with color codes respectively. Color bands should be painted on tubing and casing body longer than 600mm to either end. The whole outer-body of the coupling needs to be painted color and then color codes
| Steel Grade | Coupling | Tubular Body | |
|---|---|---|---|
| API Tubing and Casing | H40 | None | None or black band at the manufacturer’s option |
| J55 | all green. | one green band | |
| K55 | all green | two green bands | |
| N80-1 | all red | one red band | |
| N80-Q | all red + one green band | one red band + one green band | |
| L80-1 | all red + one brown band | one red band + one brown band | |
| L80-9Cr | colorless + two yellow bands | one red band + one brown band + two yellow bands | |
| L80-13Cr | colorless + one yellow band | one red band + one brown band + one yellow band | |
| C90-1 | all purple | one purple band | |
| T95-1 | all silver | one silver band | |
| C110 | all white + two brown bands | one white band + two brown bands | |
| P110 | all white | one white band | |
| Q125 | all orange | one orange band |
API 5B and 5CT provide various steel grades and color codes of each grade, offering detailed and overall information of casing and tubing, which help you clearly pick out the most suitable products for different well application.
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