TZM Alloy Welding by TIG

TZM alloy because of its good high-temperature properties are widely used in high temperature mold industry, aerospace, industrial machinery and other industries. TZM alloy as a structural material used in these areas typically require the desired shape and configuration which can achieved by welding skills. The experiment found that, in order to prevent TZM oxidation or inhaled nitrogen and other impurities in the welding process, a better method is TIG welding. Using TIG welding, it can make TZM alloy during welding process protect by inert gas (argon) to cut off the air and to prevent oxidation or nitrogen elements intrusion. The experiment found that the optimum welding parameters are as follows: welding speed 4mm / s; argon gas flow: 10L / min; welding current: 210A.

TZM alloy after TIG welding to do seam X-ray inspection found that when the welding current is 210A, the weld is flat and there is no holes and cracks on TZM surface, smooth appearance on the alloy. Observing the microstructure of welded joint found, the weld zone has coarse grains and there are some small holes, but weld microstructure is dense and no cracks. On the other hand, TZM alloy coarse grained zone and the transition zone affected by the heat of the welding process to virtually eliminate the original structure and to formed a relatively coarse equiaxed crystalline, while the original base material still maintaining crystalline sheet organizational structure. Observing its tensile strength found that the average tensile strength of welding is significantly less than the original base material. The increase of the elongation of the alloy is due to the thermal effect of the welding process to eliminate the portion of fiber texture which is formed by rolling, so that the edge of the weld is "softening." Observing the tensile fracture of TZM alloy after welding found the welding coarse grained area is not lamellar crystals, but still showing intergranular brittle fracture morphology. Coarse equiaxed grain replaced lamellar crystals, thus the weak strength of the material, but at some certain extent, improving the plastic of material can basically meet the requirements of ordinary structural.