How to Correct Weld Fillet Weld Joint?

Fillet weld is the most common welding seam splicing form in the welding process of steel structures.

Therefore, many welders will encounter different types of fillet welds, and also have different standards.

How can we weld the fillet welds well and obtain the fillet welds that meet the requirements? I’d like to give you a brief introduction today:

How to Correct Weld Fillet Weld Joint? 1

1. Selection of base metal

Let’s take the test panel of size 200 made of Q355 as an example for a brief introduction.

2. Selection of welding materials

Welding material: E5015 (J507) welding rod shall be used, the drying temperature shall be 350 ℃, the heat preservation shall be 1 hour, and the welding wire shall comply with the national standard ER50-6 (American standard ER70S-6).

3. Cleaning before welding

For fillet weld, both sides of the weld shall be cleaned within 15-20mm.

The oxide film, rust, oil and water on the plate surface shall be removed by grinding wheel or chemical treatment.

4. Assembly point fixing

Generally, the weld gap of the fillet weld shall be as small as possible.

The spot-fixing is generally carried out on the back of the plate, and the length of the spot-fixing is about 10mm.

Generally, two or three points can be fixed, as shown in the figure:

How to Correct Weld Fillet Weld Joint? 2

5. Welding parameters

Weld bead distribution

Welding level

Electrode diameter mm

Welding current A

Welding voltage

Welding speed mms

Heat input KJmm

How to Correct Weld Fillet Weld Joint? 3

a=7mm

1

3.2

120-140

/

/

/

2, 3

4.0

160-180

/

/

/

6. Welding operation

Backing weld

1.1 Electrode angle and electrode handling method

The electrode angle of root flat fillet welding is as shown in the figure: use the right welding method, strike the arc on the left side of the test plate, and perform short arc welding.

The straight electrode shall be used to weld to the right, the arc shall be aligned with the root top angle, and the arc shall be depressed to ensure the fusion of the top angle and the two side plates.

During backing welding, the swinging method adopts straight line electrode moving, and fast welding without swinging can achieve the required penetration.

How to Correct Weld Fillet Weld Joint? 4

At the starting and final welding ends of the weld, magnetic bias blowing is easy to occur, which affects the quality of the weld.

At this time, the angle of the welding rod should be adjusted properly.

Generally, the arc is pointed to the molten pool to control the magnetic bias blowing.

As shown in the figure.

How to Correct Weld Fillet Weld Joint? 5

1.2 Weld bead joint

The joint starts the arc 10 mm in front of the crater.

When the elongated arc moves rapidly to the crater, fill the crater along the crater shape, and then weld normally.

How to Correct Weld Fillet Weld Joint? 6

Cover welding

Before covering welding, remove the welding slag and spatter of the root pass to prevent slag inclusion defects.

The cover shall be welded twice. The lower weld bead shall be welded first, and then the upper weld bead.

When welding the lower weld bead, the arc shall be aligned with the lower edge of the root weld bead, the electrode shall be moved in a straight line, and the electrode angle shall be greater than 45 °;

When welding the upper weld bead, the arc should be aligned with the upper edge of the root weld bead, and the straight electrode can also swing laterally, with the electrode angle less than 45 °, as shown in the figure:

How to Correct Weld Fillet Weld Joint? 7
How to Correct Weld Fillet Weld Joint? 8

Schematic diagram of each layer of pavement

Representation of fillet size

How to Correct Weld Fillet Weld Joint? 9

Projection fillet weld

How to Correct Weld Fillet Weld Joint? 10

Recessed fillet weld

Theoretical throat: the vertical distance from the joint root to the bevel in the largest inscribed right triangle drawn in the fillet weld profile.

Effective throat: the minimum distance from the fillet weld surface to the weld root minus the raised part.

Actual throat: the shortest distance between the fillet weld surface and the weld root.

For concave fillet weld, since there is no convex part, the effective throat is equal to the actual throat.

Leg size: the distance from the root of the joint to the toe of the fillet weld.

Weld toe: the intersection point between the weld surface and the base metal.

When determining the size of fillet weld, it must be clear whether the fillet weld is convex or concave.

Convex means that the weld surface bulges slightly, which is related to the height of the bulge.

The bulge height of fillet weld is the same as the reinforcement height of groove weld.

If there is a dent in the weld, it means that there is a dished dent in the weld surface.

For these two shapes, the weld size of fillet weld with equal leg height is expressed as “the straight edge of the largest isosceles right triangle obtained in the fillet weld profile (two legs are equal in length).”

Therefore, the weld leg of convex fillet weld is equal to the weld size, but the weld leg size of concave fillet weld is slightly smaller than its weld leg length.

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