How to weld mild steel to stainless steel?

Welding mild steel to stainless steel can be a challenge for new welders who are unsure of their ability to create a high-quality joint between these two dissimilar metals. The properties and compositions of these metals are different, making the welding process more difficult than welding pure stainless steel. In this article, we will discuss the challenges of welding mild steel to stainless steel and provide some tips to ensure a successful weld.

Note: Mild steel (iron containing a small percentage of carbon, strong and tough but not readily tempered), also known as plain-carbon steel and low-carbon steel, is now the most common form of steel because its price is relatively low while it provides material properties that are acceptable for many applications.

One of the most critical aspects of welding mild steel to stainless steel is to avoid over-welding and deep penetration. This is because these metals have different melting points and thermal expansion rates, which can cause cracking, distortion, and brittleness in the joint. To prevent these issues, it's important to focus the arc more on the stainless steel portion and maintain low heat.

Related post:

Reasons You Want to Avoid Welding Stainless Steel to Carbon Steel

Maintaining low heat is essential to prevent deep penetration, preserve corrosion resistance, and prevent carbon contamination. To achieve this, you can set the lowest amperage that will melt the filler metal, travel at a fast speed, use stringer beads instead of weaving, use chill bars under or on the metals, and create a symmetrical joint that requires the least amount of weld metal. Despite the uneven angle, pointing the arc towards the stainless steel portion will result in a symmetrical bead with good toe fusion.

Differences between mild and austenitic steel for welding

Property	Mild steel	Austenitic (304) steel
Thermal expansion	65	100
Thermal conductivity	100	33
Electrical resistance	12.5	72
High-temperature strength	900 °F (480 °C)	1300 °F (700 °C )
Tensile strength	60-70ksi	85ksi
Ductility	25	55
Melting point	2800 °F (1540 °C)	2600 °F (1425 °C)
Galvanic corrosion	High	Low

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 Another challenge in welding mild steel to stainless steel is avoiding slag inclusions, which can occur when the welding process produces slag on the bead. To prevent this, the customized angle becomes even more crucial. It's also a good idea to test on similar scrap metals before welding your main project.

Contamination of the stainless steel portion with iron particles is another critical consideration in welding mild steel to stainless steel. Iron particles can cause rusting of the stainless steel portion, leading to corrosion over time. To avoid this, it's essential to use a separate set of tools to clean and bevel the stainless steel portion and avoid scratching it on any carbon steel surfaces, such as the steel portion or the welding table.

In conclusion, welding mild steel to stainless steel can be a challenging task for new welders. It requires a proper understanding of the properties and compositions of these metals and specialized techniques to ensure a successful weld. By following the tips outlined in this article, you can minimize the risks and create a strong, durable joint between these two dissimilar metals.

Reasons You Want to Avoid Welding Stainless Steel to Carbon Steel

When it comes to metalworking, welding is a commonly used technique to join different pieces of metal together. However, welding stainless steel to carbon steel is a particularly difficult task that should be avoided whenever possible. There are several reasons why welding dissimilar metals, such as stainless steel and carbon steel, can lead to problems and potentially compromise the strength and longevity of the finished product.

Difficulty

Combining dissimilar metals adds extra challenges to the welding process. Stainless steel and carbon steel have different properties, including different thermal expansion rates, melting points, and chemical compositions. Welding these two materials together creates a "dissimilar metal weld," which can cause problems such as cracking, distortion, and brittleness.

Welding stainless steel to carbon steel requires precise control of the temperature and heat input to ensure the proper fusion of the two metals. This can be difficult to achieve due to the different properties of each metal. Carbon steel has a lower melting point and is more electrically conductive than stainless steel. Welding stainless steel with resistance welding, for example, heats up the metal much faster than carbon steel. Waiting for the carbon steel to reach weld temperature can cause the stainless steel to overheat and become riddled with hot cracks. Using filler-based welding or preheating the plain carbon steel can mitigate this issue, but these methods aren't foolproof.

Related post:

Differences between Stainless Steel vs Carbon Steel?

How to weld mild steel to stainless steel?

Hot Cracking of the Stainless Steel

Hot cracking is a common issue when welding stainless steel to carbon steel. This occurs because stainless steel is more electrically-resistant than carbon steel, so it heats up faster. Waiting for the carbon steel to reach welding temperature can cause the stainless steel to overheat and become riddled with hot cracks. This problem is particularly prevalent when resistance welding stainless steel to carbon steel. Filler-based welding or preheating plain steel/mild steel can help alleviate this problem, but these methods aren't always sufficient.

Contamination

Welding stainless steel to carbon steel can also result in contamination of the stainless steel with carbon steel particles, which can lead to rust and other forms of corrosion over time.

Thermal Expansion in High-Temperature Service Conditions

This difference in expansion rates between the two metals can cause extra fatigue to the welded joint, reducing the structural integrity and useful life. In high-temperature service conditions, such as in power plants or chemical processing plants, this problem can be particularly acute. The difference in expansion rates between stainless steel and carbon steel can cause the welded joint to become fatigued, leading to structural failure over time.

Increased Bimetallic Corrosion

Stainless steel is resistant to corrosion, whereas carbon steel is not. When these two metals are welded together, the carbon steel can act as a cathode and the stainless steel as an anode in the presence of an electrolyte such as water, leading to corrosion of the stainless steel.

Stainless steel is generally used for its strong corrosion resistance. An uncovered weld of plain carbon steel and stainless steel that is exposed to extremely corrosive conditions, such as immersion in saltwater, could cause corrosion. This is because the intermingling of plain carbon steel particles with the stainless alloy compromises the protective oxide layer of the stainless, allowing rust to form. This type of corrosion is known as bimetallic corrosion and can severely compromise the integrity of the welded joint.

Reduced Weld Strength

Joining dissimilar metals can lead to weaker welds, even with filler-based welding methods. The differences in weld temperatures and operational tolerances alone can easily compromise the strength of the welded joint. Over time, this can lead to failure of the welded joint, which can be dangerous in high-stress applications.

Conclusion

Welding dissimilar metals together are difficult to do right and often produces inferior results compared to using metal alloys that are similar or the same. When it comes to welding stainless steel to carbon steel, there are several reasons why you should avoid it whenever possible. The difficulty of achieving a good weld, the risk of hot cracking, thermal expansion, increased bimetallic corrosion, and reduced weld strength all make it a risky proposition.

Differences between Stainless Steel vs Carbon Steel?

Carbon steel and stainless steel are two common materials used in various applications. Here are some of the main differences between them:

1. Composition: Carbon steel is an alloy of iron and carbon, with a maximum carbon content of 2.1%. Stainless steel is an alloy of iron, carbon, and at least 10.5% chromium, with other elements such as nickel and molybdenum added for specific properties.
2. Corrosion resistance: Carbon steel is susceptible to corrosion and rust, especially in moist or humid environments. Stainless steel has a higher resistance to corrosion due to the presence of chromium, which forms a protective oxide layer on the surface of the material.
3. Strength: Carbon steel has a higher tensile strength and yield strength than stainless steel. However, stainless steel is often used in applications where corrosion resistance is critical, such as in the food and medical industries.

Physical Properties

Physical parameter	Carbon Steel	Stainless Steel
Average Density	The average Density of Carbon Steel is 7850 Kg/m3	The average Density of Stainless Steel is 8000 Kg/m3. So Stainless Steel is slightly heavier than Carbon Steel
Co-efficient of Linear Thermal Expansion	The thermal expansion coefficient for Carbon Steel is usually less than that of stainless steel and varies in the range of (10.8 – 12.5) X 10-6 m/(m °C)	The expansion coefficient of Stainless Steel is comparatively more than that of Carbon Steel. Depending on grade, the coefficient varies in the range of (10-17.3) X10-6 m/(m °C). So, the thermal growth of Stainless Steel is more than Carbon Steel material.
Melting Point	The melting point of Carbon Steel is more than Stainless Steel. Typically Low Carbon Steel has a melting point of 1410 Deg C. The melting point of high Carbon steel ranges between 1425-1540 Deg C.	The melting point of stainless steel varies between 1375 to 1530 Deg C.

Mechanical Properties

Mechanical properties	Carbon Steel	Stainless Steel
Yield Strength	Low Carbon Steel: 180 to 260 MPa; High carbon Steel: 325 to 440 Mpa.	Ferritic Steel: 280 Mpa; Austenitic Steel: 230 MPA; Martensitic Steel: 480 MPA
Tensile Strength	Low Carbon Steel: 325 to 485 MPa; High carbon Steel: 460 to 924 Mpa.	Ferritic Steel: 450 Mpa; Austenitic Steel: 540 MPA; Martensitic Steel: 660 MPA
Elastic Modulus	2100000 Mpa	1900000 MPa
Shear Modulus	81000 Mpa	740000 MPa
Poisson’s Ratio	0.3	0.27

Other differences

Stainless Steel	Carbon Steel
Thermal conductivity is comparatively lower	Higher thermal conductivity.
Excellent wear resistance	Poor wear resistance.
Heat treatment of Stainless steel is difficult	Carbon Steel can easily undergo heat treatment.
Stainless Steel is easily cleanable	The cleanability of carbon steel is less than stainless steel.

4. Cost: Carbon steel is generally less expensive than stainless steel, although the cost can vary depending on the specific grades and applications.
5. Appearance: Stainless steel has a shiny, polished appearance and is often used in decorative applications. Carbon steel has a more matte finish and is often used in industrial applications.
6. Which is better carbon steel or stainless steel? It depends on the application and cost. For applications in a corrosive environment, stainless steel performs better than carbon steel due to its higher resistance to corrosion. For high-temperature and very low-temperature applications, stainless steel is preferred due to its better performance at extreme temperatures. However, for normal applications, carbon steel is often considered better as it is less expensive and has higher tensile strength than stainless steel. Ultimately, the choice between carbon steel and stainless steel depends on the specific needs of the application, including factors such as temperature, corrosion resistance, and cost.

Overall, the choice between carbon steel and stainless steel depends on the specific requirements of the application, such as the level of corrosion resistance, strength, and cost.

BS4360: British Standard for low and medium carbon structural steel

BS4360 is a British Standard for low and medium carbon structural steel that was published in 1968 and revised in 1990. The standard specifies the requirements for hot-rolled and forged steel bars, plates, and sections that are used in general construction, engineering, and structural applications.

BS4360 covers a wide range of steel grades, including:

• Grade 40A: This is a low carbon steel with a tensile strength of 410-560 MPa and a yield strength of 235 MPa.
• Grade 43A: This is a low carbon steel with a tensile strength of 430-580 MPa and a yield strength of 275 MPa.
• Grade 50B: This is a medium carbon steel with a tensile strength of 490-640 MPa and a yield strength of 355 MPa.
• Grade 55C: This is a medium carbon steel with a tensile strength of 550-700 MPa and a yield strength of 380 MPa.
• Grade 60C: This is a medium carbon steel with a tensile strength of 600-760 MPa and a yield strength of 420 MPa.
• Grade 65C: This is a medium carbon steel with a tensile strength of 650-820 MPa and a yield strength of 460 MPa.

The various grades of BS4360 steel are differentiated by their chemical composition and mechanical properties. They are commonly used in structural applications such as bridges, buildings, and construction equipment.

DIN 17100 ST70-2 steel plate properties and application

DIN 17100 ST70-2 is a structural steel plate that is used in various engineering and construction applications. Here are some important properties and applications of DIN 17100 ST70-2 steel plate:

1. Equivalent grades

   Europe En10025(93)	France NFA35-501	U.K. BS4360	Italy UNI7070	China GB	Japan JIS3106
   E360	A70-2		Fe 690	Q355

2. Chemical Composition: DIN 17100 ST70-2 steel plate contains primarily carbon (C), manganese (Mn), and silicon (Si) as its major alloying elements. It may also contain small amounts of other elements such as phosphorus (P), sulfur (S), and copper (Cu).
3. Carbon (C): 0.14-0.20%
4. Silicon (Si): 0.15-0.55%
5. Manganese (Mn): 0.60-1.70%
6. Phosphorus (P): 0.035% max
7. Sulfur (S): 0.035% max
8. Copper (Cu): 0.25% max (if specified)
9. Mechanical Properties: The mechanical properties of DIN 17100 ST70-2 steel plate include a minimum yield strength of 690 MPa and a minimum tensile strength of 770-940 MPa. The elongation at break is typically around 14%.
10. Applications: DIN 17100 ST70-2 steel plate is primarily used in structural applications such as bridges, buildings, and heavy machinery. It is also used in the construction of offshore platforms and in the manufacturing of pressure vessels and boilers.
11. Weldability: DIN 17100 ST70-2 steel plate is generally considered to be weldable using common welding techniques like gas metal arc welding (GMAW) and shielded metal arc welding (SMAW). However, it is important to take proper precautions to avoid issues such as cracking or porosity.
12. Corrosion Resistance: DIN 17100 ST70-2 steel plate is not designed for corrosion resistance and may corrode in certain environments. However, it can be coated or painted to enhance its corrosion resistance.

Overall, DIN 17100 ST70-2 steel plate is a high-strength structural steel that is suitable for various engineering and construction applications. Its high yield and tensile strength make it ideal for use in heavy-duty applications such as bridges and buildings.

Composition, Properties, and Applications of A240 type TP410

ASTM A240/A240M is a standard specification for chromium and chromium-nickel stainless steel plate, sheet, and strip for pressure vessels and for general applications.

The most commonly used grades are the austenitic grades such as 304, 304L, 316, and 316L, which have a high content of chromium and nickel and offer good corrosion resistance, high strength, and good formability. Other grades include ferritic and martensitic grades such as 409, 410, 430, and 440C, which offer good resistance to high-temperature and corrosive environments.

A240-TP410 is a martensitic stainless steel alloy that is commonly used in applications where high strength, hardness, and corrosion resistance are required. This alloy is also known as UNS S41000, which is its standard designation according to the Unified Numbering System (UNS).

Equivalent grades

TP410 is a martensitic stainless steel that is equivalent to several other grades of stainless steel, including:

• AISI 410
• UNS S41000
• EN 1.4006
• JIS SUS410
• GB/T 10Cr13

Composition: 

The primary alloying element in TP410 is chromium, which is present in concentrations of 11.5% to 13.5%. Carbon is also a significant component, with concentrations ranging from 0.08% to 0.15%. Other alloying elements present in smaller amounts include manganese, silicon, phosphorus, sulfur, and nickel. This composition gives TP410 its characteristic high strength, hardness, and corrosion resistance.

Properties: 

TP410 is known for its high mechanical properties, including excellent tensile and yield strength. It has a high hardness, which makes it resistant to wear and abrasion. TP410 also exhibits good corrosion resistance in mildly corrosive environments, although it is not as corrosion-resistant as some other stainless steel alloys, such as austenitic grades.

Mechanical properties

The mechanical properties of TP410 depend on various factors such as the heat treatment, manufacturing process, and other conditions.

Typically, TP410 has a tensile strength of 480 MPa (70 ksi) and a yield strength of 275 MPa (40 ksi). The elongation at break is usually around 20% and the hardness ranges from 170 to 255 HBW (Brinell Hardness).

In terms of impact toughness, TP410 exhibits moderate to high impact strength. The Charpy V-notch impact toughness is usually around 35 Joules (25 ft-lb) at room temperature. However, the impact toughness can vary depending on the temperature and the heat treatment conditions.

It is important to note that the mechanical properties of TP410 can be improved through appropriate heat treatment, such as quenching and tempering. This can result in higher strength and hardness, as well as improved toughness.

Applications: 

TP410 is commonly used in applications such as pumps, valves, and other equipment that operate in corrosive environments, such as those found in the chemical and petrochemical industries. It is also used in the construction of heat exchangers, reactors, and other process equipment.

In addition, TP410 is often used in the manufacturing of surgical and dental instruments, as well as in the production of blades and other cutting tools. Its high strength and hardness make it an ideal material for these types of applications.

Conclusion: 

TP410 is a widely used martensitic stainless steel alloy that offers high strength, hardness, and corrosion resistance. Its composition and properties make it ideal for a range of applications, particularly those in corrosive environments. While it may not be as corrosion-resistant as some other stainless steel alloys, its high strength and hardness make it a popular choice for many industrial and manufacturing applications.

 

Comparing the Composition, Properties, and Applications of Aluminum Alloys 5052 and 6061

Aluminum alloys are widely used in various applications due to their excellent properties. Two common aluminum alloys are 5052 and 6061, which have their own unique compositions and properties. In this article, we will compare the composition and properties of these two alloys.

Composition: 5052 is an aluminum-magnesium alloy that contains about 2.2-2.8% magnesium, while 6061 is an aluminum-magnesium-silicon alloy that contains about 0.6-1.2% magnesium and 0.4-0.8% silicon. Additionally, 6061 contains a small amount of copper (0.15-0.40%) and zinc (0.25%).

Properties:

1.   Corrosion Resistance: Both 5052 and 6061 have good corrosion resistance, making them suitable for use in harsh environments. However, 5052 has better resistance to saltwater and industrial chemical environments.

2.   Strength: 6061 has a higher strength-to-weight ratio than 5052, making it suitable for use in structural applications where strength is important.

3.  Formability: 5052 has good formability, but 6061 is more difficult to form due to its higher strength and hardness.

4.   Weldability: Both alloys have good weldability, but 5052 is easier to weld due to its higher magnesium content.

5.   Machinability: 6061 has better machinability than 5052 due to its lower strength and hardness.

6.   Heat Treatment: 6061 can be heat treated to improve its strength and hardness, while 5052 cannot be heat treated.

Applications:

5052 is commonly used in marine and transportation applications such as boats, ships, and aircraft, as well as structural and architectural applications such as building facades, roofs, and panels. It is also used in chemical and food processing equipment, sheet metal work, electronic components and appliances, and pressure vessels and tanks.

6061 is commonly used in structural applications such as bridges, buildings, and aircraft, as well as automotive parts, marine components, and bicycle frames. It is also used in electrical components, pipes and tubes, and sporting equipment.

In conclusion, both 5052 and 6061 aluminum alloys offer excellent properties, but they have some differences in composition, properties, and applications. 5052 is easier to form and is commonly used in marine and transportation applications, while 6061 is stronger and more commonly used in structural applications.

Comparing the Composition, Properties, and Applications of Aluminum Alloys 3003 and 5052

3003 and 5052 are both aluminum alloys that are widely used in various industries due to their excellent properties. In this article, we will compare the composition and properties of both alloys.

Composition: 3003 is an aluminum-manganese alloy that contains about 1-1.5% manganese, while 5052 is an aluminum-magnesium alloy that contains about 2.2-2.8% magnesium. Additionally, 3003 contains a small amount of copper (0.05-0.20%), while 5052 contains chromium (0.15-0.35%) and a smaller amount of copper (0.10% maximum).

3003 Aluminum Plates

Properties:

1.   Corrosion Resistance: Both 3003 and 5052 have excellent corrosion resistance, making them suitable for use in harsh environments. However, 5052 has better resistance to saltwater and industrial chemical environments.

2.   Strength: 5052 has a higher strength-to-weight ratio than 3003, making it suitable for use in structural applications where strength is important.

3.   Formability: Both alloys have good formability, but 3003 is easier to form and shape due to its higher ductility.

4.   Weldability: Both alloys have good weldability, but 5052 is easier to weld due to its higher magnesium content.

5.    Machinability: Both alloys have good machinability, but 3003 is easier to machine due to its lower strength and hardness.

6.   Surface Finish: Both alloys have excellent surface finishes, allowing them to be easily polished, anodized, or painted.

Applications:

3003 is commonly used in low-load applications that require high plasticity and good weldability, such as kitchen utensils, food and chemical product processing and storage devices, tanks, and tanks for transporting liquid products, various pressure vessels and pipes processed with thin plates, general utensils, heat sinks, cosmetic plates, photocopier rollers, and ship materials.

5052 is commonly used in marine and transportation applications such as boats, ships, and aircraft, as well as structural and architectural applications such as building facades, roofs, and panels. It is also used in chemical and food processing equipment, sheet metal work, electronic components and appliances, and pressure vessels and tanks.

In conclusion, while both 3003 and 5052 aluminum alloys offer excellent properties, they have some differences in composition, properties, and applications. 3003 is easier to form and is commonly used in low-load applications, while 5052 is stronger and more commonly used in structural and marine applications.

 

Steels: Metallurgy and Applications 3rd edition

"Steels: Metallurgy and Applications" is a comprehensive textbook that covers the metallurgy, properties, and applications of various types of steels. The third edition of the book was published in 2020 and is authored by a team of experts in the field of metallurgy and materials science.

Steels: Metallurgy and Applications 3rd edition

The book is divided into 15 chapters that cover the following topics:

1.      Introduction to Steels: This chapter provides an overview of the various types of steels and their applications.

2.      Iron and Steelmaking: This chapter covers the processes involved in the production of steel, including ironmaking, steelmaking, and casting.

3.      Alloying Elements in Steel: This chapter discusses the effects of alloying elements on the properties of steel.

4.      Steel Microstructures: This chapter covers the microstructures of various types of steels, including ferrite, pearlite, bainite, and martensite.

5.      Heat Treatment of Steels: This chapter covers the heat treatment processes used to modify the properties of steel.

6.      Mechanical Testing of Steels: This chapter covers the various mechanical tests used to evaluate the properties of steel, including tensile testing, hardness testing, and impact testing.

7.      Steel Processing: This chapter covers the various processes used to shape and form steel, including hot and cold rolling, forging, and extrusion.

8.      Stainless Steels: This chapter covers the properties and applications of stainless steels, which are widely used in a variety of industries.

9.      Tool Steels: This chapter covers the properties and applications of tool steels, which are used to make cutting tools and other applications.

10. High-Strength Low-Alloy Steels: This chapter covers the properties and applications of high-strength low-alloy (HSLA) steels, which are used in structural applications.

11. Dual-Phase Steels: This chapter covers the properties and applications of dual-phase steels, which have a microstructure consisting of both ferrite and martensite.

12. Transformation-Induced Plasticity Steels: This chapter covers the properties and applications of transformation-induced plasticity (TRIP) steels, which exhibit high ductility and formability.

13. Advanced High-Strength Steels: This chapter covers the properties and applications of advanced high-strength steels, which have been developed to meet the increasing demands of the automotive industry.

14. Corrosion and Corrosion Protection of Steels: This chapter covers the mechanisms of corrosion and the methods used to protect steel from corrosion.

15. Applications of Steels: This chapter covers the various applications of steel in industries such as construction, automotive, aerospace, and energy.

"Steels: Metallurgy and Applications, Third Edition" is an excellent reference book on different types of steels and their applications. The author has updated the latest developments in steels in areas such as metallurgy, mechanical and physical properties, heat treatment techniques, manufacturing, and applications.

The book is very easy to read and reference, with specific illustrations and tables for different types of steels and their properties. It provides readers with a comprehensive overview of steels and their properties, enabling engineers and scientists to apply this knowledge in practical applications.

Although the book is very detailed and comprehensive, it may not be suitable for beginners in the field, as it requires some background knowledge of the metals industry and techniques. Overall, "Steels: Metallurgy and Applications, Third Edition" is an invaluable resource for professionals and students in the field of metallurgy, materials engineering, steel manufacturing, mechanical engineering, and related industries.