42CrMo steel belongs to alloy structural steel in terms of material classification. It has good mechanical properties and processability and is widely used. There are mainly two types of materials: plate and round bar. Its comprehensive performance is better than 40cr and has been recognized by the industry. .
42CrMo steel is an ultra-high-strength steel with high strength and toughness, good hardenability, no obvious temper brittleness, high fatigue limit and multiple impact resistance after quenching and tempering, and good low-temperature impact toughness. 42CrMo steel is suitable for manufacturing large and medium-sized plastic molds that require certain strength and toughness.
Neutral salt bath vanadium infiltration treatment process for 42CrMo steel. 42CrMo steel can obtain carbide infiltration layer after neutral salt bath vanadium infiltration treatment.
1. Carbon vanadium compound, the infiltration layer has a uniform structure, good continuity and density, uniform thickness, dense structure, high microhardness and high wear resistance, surface hardness, wear resistance and resistance to Performance such as adhesion is greatly improved.
2. The solubility of VC in austenite is higher than that in ferrite. As the temperature decreases, VC precipitates from the ferrite, strengthening the alloy and refining the grains, and the compound layer shows higher hardness. . 42CrMo steel is a high-carbon, high-chromium ledeburite steel with a high carbide content, accounting for about 20%. It is often unevenly distributed in a band or network shape and has severe segregation. Conventional heat treatment is difficult to change the carbide segregation situation. It seriously affects the mechanical properties of the steel and the service life of the mold. The shape and size of carbides also have a great impact on the properties of steel. In particular, large, sharp-cornered carbides have a greater effect on splitting the steel matrix and often become the source of fatigue fracture. For this reason, the raw material rolled steel must be processed. Modify the forging to fully crush the eutectic carbides so that they are fine and evenly distributed, and the fiber structure is distributed around the cavity or in a non-directional manner, thereby improving the lateral mechanical properties of the steel.
During forging, the steel billet is upsetting and drawn multiple times from different directions, and the "two light and one heavy" method is used for forging, that is, the billet should be lightly struck when starting to be forged to prevent breakage, and it can be struck hard at an intermediate temperature of 980 to 1020°C. To ensure that carbides are broken, 42CrMo steel is not forged and adopts solid solution double refinement treatment, that is, secondary preheating at about 500 ℃ and 800 ℃, solid solution treatment at 1 100 ~ 1 150 ℃, quenching in hot oil or isothermal quenching , 750 ℃ high temperature tempering, 960 ℃ heating oil cooling and final heat treatment after machining, which can also refine the carbides, round edges and corners, and refine the grains.
42CrMo steel is an ultra-high-strength steel with high strength and toughness, good hardenability, no obvious temper brittleness, small deformation during quenching, and high fatigue limit and multiple impact resistance after quenching and tempering. It has good low-temperature impact toughness and high creep strength and durable strength at high temperatures. Generally used after quenching and tempering, it can replace quenched and tempered steel with higher nickel content. This steel is usually tempered and then surface quenched as a heat treatment solution.
Used to manufacture important parts with higher requirements or larger cross-sectional dimensions than 35CrMo steel, such as large gears for locomotive traction, supercharger transmission gears, rear axles, transmission gears, engine cylinders, connecting rods with extremely high loads, Spring clamps, as well as drill pipe joints and fishing tools for 1200~2000m deep oil wells, etc. This steel is also suitable for manufacturing large and medium-sized plastic molds that require certain strength and toughness.
42CrMo steel can achieve a wide range of properties through a variety of heating methods. 42CrMo steel material is able to resist creep at temperatures up to 538°C (1000°F), maintaining its properties even after prolonged exposure to relatively high operating temperatures.
42CrMo steel material has good cutting performance. Suitable for drilling, sawing, broaching, tapping, milling and other processing.
But 42CrMo steel material is not easy to weld. 42CrMo steel is not recommended for welding in the quenched and tempered (QT) state. Because it will change the mechanical properties in the heat-affected zone of 42CrMo steel welding. Under annealed conditions, 42CrMo steel is allowed to be welded. However, if 42CrMo steel needs to be welded in the quenched and tempered state, the workpiece must be cooled immediately and the stress relieved at 15°C lower than the original tempering temperature.