X70 (manual arc welding, welding wire) metallographic diagram

The microstructure of X70 weld specifies the properties of the steel, which affects the overall performance of the component. X70 welds are most commonly created using manual arc welding with a consumable electrode form of wire. The welds are composed of approximately 97-99% ferrite and 1-3% of other compounds, depending on the alloy and composition of the material. The composition of the weld will determine the hardness, ductility, and strength of the steel, which is important to consider when selecting weld materials for a specific application. Due to the large amount of ferrite and other compounds present in the weld, it is very important to test the materials before proceeding to production.

Microstructure of X70 welds can be easily observed by using light optical microscopy and metallographic techniques. Examination of the microstructure of this alloy will reveal the presence of ferrite grains, as well as compounds such as oxide and nitrides. These compounds, when present in an excessive amount, can weaken the strength of the weld and reduce the overall properties of the piece. Additionally, examining these components under the microscope allows for an assessment of the welding conditions and how they affect the weldment.

To evaluate the microstructure of X70 welds, metallographic examination is recommended. This type of analysis involves analyzing the samples through a 100X magnification and then evaluating the alloy composition and microstructure. The results of the examination will provide critical information on the properties of the steel and allow for the identification of potential causes for flaws and defects in the weldment.

It is important to understand the microstructure of X70 welding to ensure the highest quality and performance of the components. The proper techniques should be used when examining the metals, including visual inspection, hardness testing, and metallographic examinations. The results of the analysis should be recorded and assessed to ensure that X70 welds meet required performance specifications. This type of attention to details helps to reduce the risk of defects and issues and improve the overall performance and reliability of the original product.

The microstructure of AWS A5.17 E7018-1 (manual arc welding with electrode) weld metal was examined using a metallurgical microscope. The results show that the microstructure consists of acicular ferrite, proeutectoid ferrite, pearlite, and ferrite-pearlite lamellar structure.

The acicular ferrite was evenly distributed in the entire weld metal, distributed along with the heat conduction direction of the welding process, and observed to be lath-like form. The acicular ferrite has a higher degree of purity, uniform and stable in size, with a mean size of 20 to 40 μm.

The proeutectoid ferrite also exists in the entire weld metal, and the mean size was about 20 to 40 μm. The proeutectoid ferrite was observed to be in a round-like shape, seeming like isolated nodules dispersed around the acicular ferrite regions.

Pearlite, in a lamellar form, was distributed along the 1-20 mm-thick boundaries of the weld pass and between the proeutectoid ferrite. The ferrite-pearlite lamellar structure formed a band near the weld boundaries, which contained fine ferrite particles and pearlite.

In conclusion, the weld metal of AWS A5.17 E7018-1 (manual arc welding with electrode) consists of acicular ferrite, proeutectoid ferrite, pearlite, and ferrite-pearlite lamellar structure. The acicular ferrite is lath-like form, and the proeutectoid ferrite is round-like shape, the pearlite is in a lamellar form, and the ferrite-pearlite lamellar structure is distributed near the weld boundaries.