AMIE INDIA Students Forum

[navin_rdy]

A welding defect is any flaw that compromises the usefulness of the finished weldment.

According to the American Society of Mechanical Engineers (ASME) welding defect causes are broken down into the following percentages: 41% poor process conditions, 32% operator error, 12% wrong technique, 10% incorrect consumables, and 5% bad weld grooves

please see the attachment for further details..

Naveen

[geetha410]

Hi navin, thank u soo much for your attachment
and u will be given super membership please wait and do post valid post
we went through all your post some of the post was just blank so don't repeat that

[swananddeodhar]

Major defects in welding are caused by the use of moist welding electrodes in SMAW process. This causes water vapor to trap and cause porosity in the weldment. To avoid this electrodes should be properly baked (generally from 150 to 450 deg. celcius) depending on the type of electrodes. Baking ovens are available in the market. The temperature should be set as per the instructions on the electrode case or box. This will avoid the defects.

[swananddeodhar]

The preheating of the material to be welded is to be followed to get a good welding. This is to ensure removal of moisture from the surface. This process of preheating (generally up to 200 deg. Celcius) removes moisture from the surface and also degrease the material.

[swananddeodhar]

Excessive current and fluctuation in current and voltage also causes defects. The temperature difference caused due to this fluctuation causes carbides formation in the heat affected region. Increase in current will cause the temperature to rise which will result in the cooling rate, ultimately resulting in the material to become hard and brittle in the heat affected zone. So control of the arc and temperature is necessary to avoid typical defects like cracking of base material and lamillar tear.