10 Questions You Should to Know about Welding Consumables

20 questions about welding

1. What is welding?

Welding is a family of methods used for joining two workpieces; steel in the case of SSAB. Usually a single heat source, normally an electrical arc, locally melts the two workpieces to form a common liquid pool. When the steel solidifies, the pieces are joined. In many cases, a special steel rod or wire (consumable, filler) is melted into the weld pool to get a good weld joint.

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2. What are the most common welding methods?

The most common welding methods are Shielded Metal Arc Welding (SMAW) more commonly known as MMA or stick welding, Tungsten Inert Gas (TIG), Gas Metal Arc Welding (GMAW) more known as MIG/ MAG welding, submerged arc welding (SAW) and laser welding.

3. Can different welding methods be combined?

Yes. A typical example can be to weld the root pass with TIG and fill passes with MIG/MAG. 

4. Can all steels be welded?

Yes, but it is more challenging to weld some steels than others, depending on alloying and dimensions.

5. How can different steels be welded together?

Welding methods and parameters must be suitable for both steels. Usually, the least weldable steel determines the parameters to be used. 

6. What are the welding consumables?

There is a vast number of consumables. The steelmaker provides advice on these for their different grades. For SSAB steels, see the welding recommendations.

7. How is steel preheated before welding?

Workpieces can be preheated in a furnace with an oxy-fuel flame, with electrical heating mats or with electrical induction. It is crucial not to exceed the maximum temperatures given in the data sheet for the steel grade to be welded. Too high a temperature may negatively affect the properties of the steel.

8. How is welded steel postheated after welding?

Steel workpieces can be preheated in a furnace with an oxy-fuel flame, with electrical heating mats or with electrical induction. It is crucial not to exceed the maximum temperatures given in the data sheet for the steel grade involved. Too high a temperature may negatively affect the properties of the steel.

9. How much hydrogen is allowed in the welded joint?

A rule of thumb is a maximum of 5 ml hydrogen per 100 g weld metal. However, this is in practice not possible to measure. The hydrogen content in solid wires for MAG welding is typically around 1.5-2 ml hydrogen per 100 g weld metal, while cored wires can pick up moisture in the flux which might increase to higher values per 100 g weld metal. Keep all consumables dry and warm, in particular flux-covered and flux-core ones. Packages should be opened shortly before use. 

11. What steels can be welded using hardfacing?

Hardfacing is a procedure where a harder material is welded to the base metal surface to create a protective layer. The method can be applied to all SSAB steels, but for the hardest ones, a soft buffer layer must first be welded on the base plate to reduce the risk of cold cracking into the base plate. All types of conventional welding processes can be used for both the buffer layer and the hardfacing layer.

12. Can welding be done on the primer?

Yes, it can. However, the primer will increase the porosity in the welded joint. A high-quality weld calls for complete removal of the primer in the welding area. 

13. How much hardness or strength is lost after heating the material?

Hardness deterioration is difficult to control. The maximum heating temperatures stated in the data sheets of the steel should always be respected.

14. What is the heat-affected zone (HAZ) of steel?

The heat-affected zone (HAZ) is close to the welded joint where the temperature has increased temporarily due to the liquid weld pool. HAZ size depends on the heat applied. The mechanical properties of the base steel in the HAZ may change, usually in a negative direction. 

15. How big should the throat thickness be for fillet welds?

The designer has chosen a suitable plate thickness for the expected structural stresses. A rule of thumb is that the throat thickness is equal to the plate thickness for a one-sided fillet weld. For two-sided fillet welds, the throat thickness should be approx. 0.7 times the plate thickness.

16. Why does the plate deform after welding?

Plate shrinkage in the vicinity of the welded joint will vary due to varying peak temperatures and residual stresses of varying sizes will appear. Thin plates will react with deformation and relaxation of the stresses, while the stresses will prevail in thick plates.  

18. What are hydrogen cracks?

Hydrogen cracks in welded joints can form due to the concentration of hydrogen in the material close to the weld, as hydrogen embrittles the material. Hydrogen atoms in a hot welded joint will diffuse and collect at “comfortable” spots, e.g. microdefects in the microstructure. Hydrogen gets trapped when the joint cools. Cracks can initiate from those hydrogen traps after hours or even days. The inevitable residual stresses will elongate the cracks. High hardness and alloying make steels more sensitive to hydrogen cracking. 

19. What can cause a welded joint to fail?

There are many factors that could cause a welded joint to fail. The most common ones are defects in the form of physical discontinuities, poor microstructure, and residual stresses. There are various reasons behind those factors, including choice of design, joint type, joint geometry, welding process, heat input, preheating, and welding consumables. 

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Welding is a fantastic skill that can open the door to many projects, from custom auto repairs to metal furniture design. However, it also comes with a learning curve and plenty of questions! Whether you’re just starting out or looking to polish your technique, here are answers to the ten most commonly asked welding questions to help you weld with confidence.

1. What’s the Best Type of Welder for Beginners?

If you’re new to welding, the best starting point is often a MIG welder. MIG welding is user-friendly and versatile, making it ideal for a range of general projects. It’s particularly good for those learning to control a steady arc while achieving clean welds.

For those interested in more specialized work:

• TIG welding offers greater precision but requires practice to master.
• Stick welding is affordable and effective outdoors but is typically more challenging for beginners.

Example: If you’re working on auto repairs or metalwork around the house, a MIG welder is a solid choice to get started.

3. What Safety Gear Do I Really Need?

Safety is crucial in welding, and wearing the right protective gear can save you from burns, UV damage, and debris.

• Helmet: An auto-darkening helmet protects your eyes and adjusts to changing light, so you can work hands-free.
• Protective Clothing: Heat-resistant gloves, a welding jacket, and long pants are must-haves to guard against sparks.
• Extras: Ear protection, safety glasses, and ventilation are essential for protecting your ears, eyes, and lungs.

Example: Even if you’re just doing a quick weld, always wear gloves and an auto-darkening helmet to shield your eyes from UV burns.

4. Why Does My Weld Look Porous?

Porous welds are often the result of contaminants on the metal or improper shielding gas flow.

• Clean the Metal: Rust, oil, and dirt can lead to holes in your weld.
• Check Gas Flow: Low or high gas flow and windy conditions can cause gas to dissipate, leading to porosity.

Example: If you notice small holes in your welds, double-check that your gas flow is appropriate and that the metal is clean and free from contaminants.

5. How Can I Avoid Distortion When Welding Thin Metal?

Thin metals are prone to warping under heat, but you can control distortion with a few adjustments.

• Tack Welds: Use tack welds at intervals to reduce heat buildup.
• Lower Amperage and Quick Movement: Lowering amperage and moving quickly also help keep heat low.

Example: When welding sheet metal, use tack welds every few inches and weld in short bursts to prevent the material from warping.

7. How Do I Prevent Cracks in My Weld?

Cracks can be caused by incorrect filler material, overheating, or putting stress on the metal.

• Select Proper Filler Material: Match the filler with the base metal to avoid cracks.
• Avoid Overheating: Too much heat can make the weld brittle, leading to cracking.

Example: If you’re welding stainless steel, using a compatible filler material and controlling heat will keep the weld crack-free.

8. What’s the Best Way to Weld Outdoors?

Welding outdoors can be challenging due to wind, which can blow away your shielding gas.

• Use Wind Shields: Set up barriers around your welding area.
• Stick Welding Advantage: Stick welding is generally better outdoors as it doesn’t rely on gas shielding.

Example: On a windy day, use windshields or switch to stick welding to avoid gas-related issues.

Contact us to discuss your requirements of Mig Welding Wire. Our experienced sales team can help you identify the options that best suit your needs.