Welding technique is one of the joining methods in industrial field, especially metal manufacturing. Welding methods can be categorized into three that are press welding, liquid welding and soldering. The purpose of this study is to determine the influence of the friction time variation toward the micro structure and mechanical characteristic. The materials used in this study are a steel cylinder solid low carbon S20C and medium carbon S45C. The parameters used is 4 seconds, 6 seconds, and 8 seconds-friction time variation. The rotated of friction welding machine used is 1000 rpm. The friction pressure used is 30 MPa and the upset pressure is 70 Mpa. The test used in this study a micro structure test, a hardness value test and a tensile strength test. Based on the results, in the welded area a micro structure occurs granular compaction along with the increasing of the friction time variation used so the micro structure granules look increasingly fused. The highest vickers hardness value is obtained from the variation of welding conditions I (low carbon steel rotated and medium carbon steel fixed) with a 6 seconds-time variation is 278.4 VHN and the lowest hardness value is 231.8 VHN in welding condition I (low carbon rotating steel and medium carbon fixed) with a 8 seconds-time variation. While the tensile test results obtained the highest average tensile strength is 701.51 N / mm² in condition II (medium carbon steel rotated and low carbon steel fixed) with a 4 seconds-friction time variation, and the lowest average tensile strength is 622.22 N / mm² in condition II with a 8 seconds-friction time variation