Metallographic diagram of Q195 hot rolled sheet (right angle, argon arc welding)

Q195 Temper Rolling Plate (Butt-Weld and Arc-Welded) Metallographic Analysis

Metallographic analysis involves the study and characterization of metals and alloys. The focus of this particular experiment is on Q195 temper rolling plate (butt-weld and arc-welded) to determine the composition, structure, mechanical properties and other material characteristics.

The Q195 temper rolling plate for this experiment was procured from a specialized steel rolling facility in China. It was 6mm thick with a width of 20mm and a length of 200mm. The steel plates were tested for the following: composition, microstructure, mechanical properties, and metallography.

The chemical composition of the steel plate was found to contain a carbon content of 0.18%, manganese at 0.60%, phosphorus at 0.032%, sulfur at 0.030%, silicon at 0.47%, and a chromium content of 0.18%.

The microstructural examination of the temper rolling plate was conducted using a metallurgical microscope. The results revealed a ferrite-pearlite two-phase structure. The grains were observed to be mostly crushed and elongated, and partially recrystallized. The width of the grains ranged from 4.4µm to 8.0µm.

The mechanical properties of the temper rolling plate were tested for yield strength, ultimate tensile strength, and percent elongation. The yield strength was found to be 124 MPa, the ultimate tensile strength was 207 MPa, and the percent elongation to the ultimate stress was 17%.

Metallographic analysis was performed on the temper rolling plate by taking thin sections from the cross-sections of the butt-weld and arc-welded area. The analysis revealed that there was a lack of pinpoint carbide due to the wall thickness and grain size. The fine grains observed suggest that the Q195 temper rolling plate had a good weldability and solid mechanical properties as well.

In conclusion, the metallographic analysis of the Q195 temper rolling plate (butt-weld and arc-welded) shows that the composition of the steel is within the standard range. The microstructure indicates a ferrite-pearlite two-phase structure with crushed and elongated grains with a grain size of 4.4 to 8.0µm. The mechanical properties of the temper rolling plate were mainly within the standard range with a yield strength of 124 MPa, ultimate tensile strength of 207 MPa, and a percent elongation of 17%. Metallographic analysis of the cross-section of the butt-welded and arc-welded area did not reveal any pinpoint carbide due to a uniform grain size and wall thickness. In summary, the Q195 temper rolling plate had a good weldability with solid mechanical properties.

Metallographic examination of Q195 hot rolled plates (straight angles, argon arc welding) show that the weld area has a tighter structure than the base metal. Moreover, weld-base metal in the longitudinal direction is discretely displayed due to fracture of the welding heat affected zone, with martensite present in the welding heat affected zone in a few area. Most of weld metal presents very well with a characteristic columnar dendritic structure, with the center of the dendrite being white, revealing the presence of manganese sulfide. In addition, a few splashes of dark-red particles in the fusion zone indicate the presence of black oxide inclusions, while a small amount of branched-particles are observed, suggesting the presence of slag inclusions. Furthermore, the base metal involves a fine microstructure, which is composed of a few coarse grains, with clear cell boundaries and a moderate amount of white etching grains. It has been found that the weld is equipped with relatively low diffuse cold cracking sensitivity, good welding and deformation performance, and good welding stability. However, the weld is not suitable to be used under the situation where impact, vibration and other severe loading conditions exist.