Adding niobium as a carbide element to steel can play an important role in modifying the microstructure of steels. This element, by forming fine precipitation, reduces grain size and thus improves the mechanical properties of steels. In this study, the effect of adding niobium on the grain size and the mechanical properties of 1.7016 steel has been investigated. First, using the casting process, primary steel samples were produced with weight percentages of 0.02, 0.06, 0.09 %wt niobium. After the casting process, the samples were placed at a temperature of 850 ° C for 15 minutes and forged for reformation of the casting structure under the same load. The specimens were divided into two groups, one group was directly subjected to microstructural and mechanical examinations and the second group was initially carbonized using a solid state barbed process at 940 ° C and 7 hours and then quenched in oil. The results of the first group showed a decrease in the grain size from 7.9 ?m to 7.4 ?m for non-niobium and 0.6%wt niobium specimens, While in the sample 0.09%wt niobium, the grain size again increased to 6 ?m. Samples of the second group decreased grain size from 4.7?m to 1.8?m with increasing niobium up to 0.6%wt from micrometers. Because in this range of austenite, the austenite phase starts to sprout and due to the presence of niobium in the structure, it is not possible to move the grains and grow . This results in a smaller grain size, Also, hardness results in both groups showed an increase in hardness to samples containing 0.06%wt niobium, While the niobium is 0.09%wt, the hardness decreases again The reason for this can be due to grain size variations, the size and size of the distributed sediments in the structure and the different amounts of residual austenite phase in the structure. The results of tensile analysis showed that the highest tensile strength in both steel groups was related to 0.6%wt niobium specimens. Whose values ??for the first and second groups were 776 and 948 MPa respectively. The second group steels showed a slight increase in uniform length due to the formation of crisp phases on the surface layer during the barbed process The calculations concerning the toughness of the steels showed that the highest toughness of the steel is 0.06%wt niobium without heat treatment which is 180 MPa.