1. Grade Overview
35CrMo is a chromium molybdenum alloy steel defined in GB/T 3077, supplied as plate, sheet and bar for components that require high strength combined with good toughness. The grade number indicates a nominal carbon content of 0.35 percent with chromium and molybdenum as the main alloying elements. Because the steel responds well to quenching and tempering, it is the standard material for heavy duty machine parts and structural components that carry high alternating loads.
2. Chemical Composition
The composition of 35CrMo is tightly controlled to give consistent hardenability. A typical specification range is carbon 0.32 to 0.40 percent, silicon 0.17 to 0.37 percent, manganese 0.40 to 0.70 percent, chromium 0.80 to 1.10 percent and molybdenum 0.15 to 0.25 percent, with phosphorus and sulphur each limited to 0.030 percent. Chromium increases hardenability and strength, while molybdenum raises the tempering resistance so that the plate keeps its strength at moderate service temperatures.
| Element | Typical Range in Percent |
| Carbon | 0.32 - 0.40 |
| Silicon | 0.17 - 0.37 |
| Manganese | 0.40 - 0.70 |
| Chromium | 0.80 - 1.10 |
| Molybdenum | 0.15 - 0.25 |
| Phosphorus and sulphur | 0.030 max each |
3. Heat Treatment and Mechanical Properties
35CrMo plate is normally delivered in the quenched and tempered condition. Quenching from about 850°C in oil or water produces a martensitic structure, and tempering in the range of 540 to 620°C sets the final strength and toughness. In the quenched and tempered condition the steel develops a minimum tensile strength of 980 MPa, a minimum yield strength of 835 MPa and a minimum elongation of 12 percent, with the hardness depending on the tempering temperature.
4. Forming and Welding
In the quenched and tempered condition the plate can be machined, but forming and welding need controlled procedures. Welding should be carried out with preheating in the range of 150 to 250°C using low hydrogen consumables, and post weld heat treatment is recommended for heavily restrained joints. Plasma or laser cutting produces a hardened cut edge that should be removed by grinding before welding, and thick sections benefit from preheating before cutting.
5. Typical Applications
Gear shafts, connecting rods and heavy duty fasteners.
High pressure vessel components and flanges.
Machine tool spindles and structural members of presses.
Wear and impact parts in construction machinery.
Bolts and studs for high strength bolted connections.
Frequently Asked Questions
Q: What does 35CrMo mean in the grade designation? The number 35 indicates a nominal carbon content of 0.35 percent, and Cr and Mo show that the steel is alloyed with chromium and molybdenum.
Q: What hardness can be expected after quenching and tempering? The hardness depends on the tempering temperature and the section thickness; typical values range from about 220 HB after high temperature tempering up to around 320 HB for lower tempering temperatures.
Q: Is 35CrMo plate difficult to weld? It is weldable with proper procedure, including preheating, low hydrogen electrodes and post weld heat treatment for restrained joints; the heat affected zone must not be left hardened.
Q: Can the plate be supplied in the annealed condition? Yes, the annealed condition is available for applications that will be machined and heat treated later, but the quenched and tempered condition is the standard delivery for direct use.
Q: What is the difference between 35CrMo and 42CrMo? 42CrMo has a higher carbon content of about 0.42 percent, which gives it higher strength after hardening with slightly lower ductility and weldability compared with 35CrMo.