Grade Overview
35CrMo is a chromium molybdenum alloy steel defined in GB/T 3077 and supplied as hot rolled plate, sheet and bar. The designation indicates a nominal carbon content of 0.35 percent together with chromium and molybdenum as the main alloying additions. These elements raise hardenability and tempering resistance, so the steel can be quenched and tempered to a high strength level while retaining good toughness. Plate in this grade is used for machine parts and structural components that carry heavy alternating loads and work at moderate service temperatures. It is one of the most widely used alloy steels in Chinese and international practice, and it is readily available in thicknesses from 6 mm to 200 mm and in widths up to 2500 mm.
Chemical Composition
The composition of 35CrMo is controlled within a narrow range to give consistent hardenability from heat to heat. Typical values are given in the table below.
| Element | Typical Range in Percent |
| Carbon | 0.32 to 0.40 |
| Silicon | 0.17 to 0.37 |
| Manganese | 0.40 to 0.70 |
| Chromium | 0.80 to 1.10 |
| Molybdenum | 0.15 to 0.25 |
| Phosphorus and sulphur | 0.030 maximum each |
Chromium increases hardenability and strength, while molybdenum raises tempering resistance so the plate keeps its strength at moderately elevated temperatures. Low phosphorus and sulphur keep the steel clean and improve impact toughness.
Heat Treatment and Mechanical Properties
35CrMo plate is normally delivered in the quenched and tempered condition. Quenching from about 850 degrees Celsius in oil or water produces a martensitic structure, and tempering between 540 and 620 degrees Celsius sets the final balance of 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 hardness depending on the tempering temperature. Wear resistant alloy plate such as NM500 is a different product family. It is not intended for quench and temper through the full section; instead it is supplied with a controlled surface hardness of 470 to 540 HBW under GB/T 24186 so that the working face resists sliding abrasion while the core stays tough enough to absorb impact.
Thickness Selection and Fabrication
For a 10 mm alloy plate sheet the choice between 35CrMo and a wear grade depends on the duty. Use 35CrMo where the part must transmit load and be machined to a finished shape. Use NM500 or NM450 where the surface is exposed to ore, coal, gravel or slag and thickness loss is the main failure mode. Both product types can be cut by plasma, laser or water jet. Thermal cutting leaves a hardened edge that should be dressed by grinding before welding. When welding 35CrMo, preheat in the range of 150 to 250 degrees Celsius with low hydrogen consumables and apply post weld heat treatment on restrained joints. Wear plate is normally joined to a structural backing plate, and a low hydrogen procedure with light preheat is sufficient for thin sections.
Typical Applications
Gear shafts, connecting rods and heavy duty fasteners.
High pressure vessel components and flanges.
Machine tool spindles and press structural members.
Chute liners, hopper wear strips and bucket lips in NM500.
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, while Cr and Mo show that the steel is alloyed with chromium and molybdenum to improve hardenability and tempering resistance.
Q: What hardness can be expected after quenching and tempering?
Hardness follows the tempering temperature and section thickness, ranging from about 220 HB after high temperature tempering up to roughly 320 HB at lower tempering temperatures.
Q: Is 35CrMo plate difficult to weld?
It is weldable with a controlled procedure that includes preheating, low hydrogen electrodes and post weld heat treatment for restrained joints so the heat affected zone is not left hardened.
Q: Can the plate be supplied in the annealed condition?
Yes, the annealed condition is available for parts that will be machined and heat treated later, although quenched and tempered delivery is standard for direct use.
Q: How does NM500 compare with 35CrMo for a 10 mm plate?
NM500 offers much higher surface hardness for abrasion resistance, while 35CrMo offers higher core strength and better machinability for loaded mechanical parts.