Method for improving properties of H13 die steel by adding nitrogen

Abstract

The invention relates to a method for improving properties of H13 die steel by adding nitrogen and belongs to the field of metal materials. In the method, chemical compositions of conventional H13 steel are improved, the strength, hardness and abrasive resistance of the die steel are improved by adding solid solution nitrogen element, and the toughness is not reduced. The nitrogen element is added by a method of adding a chromium nitride preliminary alloy, and other elements are added by a conventional method. In order to ensure yield of the nitrogen element during smelting, and reduce overflowing in the process of smelting and air bubbles during solidification, a smelting temperature is strictly controlled to be higher than a melting point within 50 DEG C, and the casting is quickly performed after the alloys completely smelt. The nitrogenous H13 die steel comprises the following chemical compositions by percentage: 0.28 to 0.40 percent of carbon, 0.8 to 1.2 percent of silicon, 0.2 to 0.5 percent of manganese, 4.75 to 5.5 percent of chromium, 1.10 to 1.75 percent of molybdenum, 0.8 to 1.2 percent of vanadium, 0.02 to 0.08 percent of nitrogen, less than or equal to 0.03 percent of phosphorus, less than or equal to 0.03 percent of sulfur and the balance of Fe. A forge piece after thermal treatment has the following properties: the hardness value is 53 to 55HRC, the tensile strength is over 1,800MPa, the yield strength is over 1,480MPa, the impact absorption power value is between 15 and 16 J, the strength and hardness are higher than those of the H13 steel, and the toughness is not lower than that of the H13 steel.

Description

technical field [0001] The invention belongs to the field of metal materials, and relates to an H13 die steel. The chemical composition of the H13 die steel is improved, and the strength, hardness and wear resistance of the H13 steel are improved by adding solid-dissolved nitrogen atoms. Background technique [0002] Due to its high performance and low cost, nitrogen-containing steel has attracted widespread attention in the iron and steel industry [Gan Yong, Dong Han, Advances in Advanced Iron and Steel Materials Technology, China Metallurgy, 2004, (8): 1-6]. Nitrogen, as a solid solution strengthening element in steel, will not cause the precipitation of intergranular carbides like carbon, so nitrogen will not reduce toughness while increasing the strength of steel. At present, the strength of high-nitrogen steel can reach up to 3600MPa, and it is expected to reach 4000MPa soon, and its toughness is higher than that of steel with the same strength [M.Milititsky, et al., Im...

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Problems solved by technology

For large-scale industrial profile tooling molds, due to their higher requirements on wear resistance, strength, and toughness, domestic molds can hardly meet the use requirements.

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