Abstract Steel 4330V is a material that contains an addition of vanadium (approximately 0.06 wt. %). The steel is widely used in the mining and petroleum industries. The steel microstructure contains tempered martensite. The high carbon equivalent of the steel makes it difficult to weld. The simulation of the heat-affected zone (HAZ) makes it possible to determine the effect of an increase in temperature on the properties and the structure of the steel. The simulation of heating was performed using a resistive heating device. The specimens were heated between 2 and 8 s at a temperature restricted within the range of 300°C–1,300°C. During the tests, temperature was recorded using a thermal imaging camera. The tests revealed that up to a temperature of approximately 600°C, the material did not undergo structural changes. Above a temperature of 600°C, the hardness of the specimen increased to 500 HV. As the temperature of the HAZ increases, the grain size changes, which in turn affects the change of mechanical properties. Results of the impact strength tests performed at a temperature of –40°C confirmed hardness values and results of micrographic examinations.