40H steel is a structural steel for tempering. It is one of the most popular grades, finding use in many industries. After the tempering treatment, it is characterized by high mechanical properties, especially high strength and yield strength, with good ductility properties at the same time. Hardening is carried out at a temperature of about 850℃ in oil, and tempering is carried out in water or oil from a temperature of about 500℃.
It belongs to the group of chromium steels, which additionally contains elements such as carbon, manganese, silicon and nickel. Thanks to the appropriate content of these alloying elements, this steel is resistant to corrosion and can be intended for components operating in harsh atmospheric environments. Both chromium and manganese and manganese-silicon steels are used for the manufacture of parts with small cross-sections (e.g., up to 100 mm, when they do not require through-hardening), since their hardenability compared to other steels of this group is relatively small. Welding this grade of steel is not easy, it is recommended to heat the parts before the welding operation, and another heat treatment is required after completion.
The advantage is the susceptibility to machining, including machining, and heat treatment, such as hardening, tempering, normalizing annealing and softening annealing.
Steel 40H chemical composition
| Designation | C % max | Mn % max. | Si % max | Cr % max | P % max. | S % max. | Ni % max. | Cu % max. | |
|---|---|---|---|---|---|---|---|---|---|
| 40H | 1.7035 | 0,36 - 0,45 | 0,50 - 0,90 | 0,17-0,37 | 0,80-1,20 | 0,025 | 0,035 | 0,30 | 0,25 |
Steel 40H mechanical properties
| Mechanical properties | ||||
|---|---|---|---|---|
| Rp0,2 [MPa] | Rm [MPa] | Hardness [HB] | Elongation % | Elongation % |
| ≥870 | ≥980 | <240 | ≥10 | ≥45 |
40H steel application
The application of 40H steel is very wide, as a structural steel it is used for the construction of components and parts of vehicles, machinery and structures.
It is most often used for the manufacture of components subjected to heavy loads, these include:
- shafts, axles, connecting rods, gears, bushings, pins, turbine components, gears
- for the manufacture of tool shank components
- in the automotive industry for the manufacture of crankshafts, camshafts, transmission components.
| EU EN | Steel number | PN | USA AISI | Russia |
| 41Cr4 | 1.7035 | 40H | 5140 | 40Ch |
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