This study investigates TIG welding current variations effects on 4 mm thickness AISI 304 stainless steel joint welded using Argon gas, and this process impacts on ferrite composition, structural properties and joint strength. Ferrite content control must be managed properly to prevent hot cracking while ensuring both material strength and corrosion resistance because improper management leads to deficits during welding operations. A set of welding currents starting at 100 A progressed to 150 A and ending at 190 A created welds which delivered heat inputs of 6 J/mm, 9 J/mm and 11.4 J/mm. Welds under each condition received full inspection using metal structure analysis, scanning electron microscopy (SEM) along with Ferritoscope ferrite measurement, Vickers hardness analysis and mechanical strength testing. Data showed that a rise in heat intensity led to more ferrite formation starting from 4% at 100 A up to 9% at 190 A. The welds with 150 A heat application produced the optimal combination of mechanical properties since they contained 6% ferrite and displayed peak tensile strength at 689 MPa and mid-range hardness from 160–170 HV along with increased resistance to hot cracking. The welding current at 100 A produced a high hardness level of 170–181 HV in the weld but lost strength because of excessive ferrite content. Meanwhile the weld at 190 A exhibited lower strength and reduced hardness (150–157 HV) due to its excessive ferrite formation. Because of its ability to achieve superior microstructure with desirable austenite-to-ferrite ratio the weld using 150A heat input delivers optimal weld quality. The current investigation establishes quantitative assessments about heat treatment effects on AISI 304 TIG welds which distinguishes itself from previous research. The integration of Schaeffler diagram modeling with direct ferrite evaluations paired with SEM verification leads to a superior method for welding process prediction and enhancement.