High-hardness high-tenacity cold and hot work die steel and production method thereof

Abstract

The invention relates to die steel, in particular to high-hardness high-tenacity cold and hot work die steel which comprises the components in percentage by weight as follows: 0.50-0.65% of C, 0-0.35% of Si, 0.20-0.50% of Mn, 5.00-6.00% of Cr; 1.00-2.30% of Mo; 0-1.50% of W, 0.40-1.00% of V, no more than 0.25% of Nb, no more than 1.00% of Co, no more than 0.01% of S, no more than 0.025% of P and the balance of Fe and impurities. At the same time, the weight percentage which meets the requirement of Mo plus 0.55 W accounts for 1.80-2.30%, and the carbon saturation Ac is 0.90-1.10. The invention further provides a production method of the high-hardness high-tenacity cold and hot work die steel. Compared with conventional hot work die steel, the high-hardness high-tenacity cold and hot work die steel has the advantages that the steel has a wider application hardness range (54-58 HRC), higher strength (4000-4700 MPa), high tenacity (no less than 200J / cm <2>), temper-resistant stability and higher overall performance.

Description

technical field [0001] The invention relates to a mold steel, in particular to a high-hardness, high-toughness cold-heating mold steel; the invention also provides a production method of a high-hardness, high-toughness cold-heating mold steel. Background technique [0002] Traditional hot work die steels include 3Cr2W8V (H21), Cr5 types (H13, H12, H11, SKD61, etc.), and the latest Cr5 series hot work die steels (W400, DIEVAR, ADC3, GS344M, GS999, DAC55, DH31- S, etc.), Cr3 series hot work die steels (foreign QRO45, QRO80, QRO90, H10, etc., domestically developed 3Cr3Mo3V, HM1, HM3, GR, HD, TM, Y4, etc.), have their own advantages in terms of toughness and strength improvement, However, the applicable hardness of these hot work die steels is in the range of 35-55HRC, and their hardness is low; while the newly developed Cr8 series high toughness and high wear resistance cold work die steels LD, HYC3, GM, DC53, ER5, Cr8MoV2Ti , 80Cr7Mo3W2V, DC53, ASSAB-88, CRU-WEAR, QCM8, LEXC...

AI Technical Summary

Problems solved by technology

Due to the low hardness and strength (below 54HRC), the steel material used for the mold cavity in the past, the nose part wears and deforms faster, the toughness is insufficient, and early fractures are prone to occur, making it difficult to maintain the life of the mold

Therefore, after a detailed investigation and analysis of the reasons for mold scrapping, it is concluded that: ① low hardness, insufficient strength and insufficient softening resistance are the main reasons; ② the existing mold steels all emphasize the important role of Si on secondary hardening, However, Si has a very adverse effect on the reduction of toughness, and it is also unfavorable for the stability against tempering; ③When the heat treatment hardness is high, the grains are coarsened and the toughness is low; The impurity of non-metallic inclusions, etc., have a great influence on the toughness and uniformity of steel, resulting in carbides and non-metallic inclusions as the source of cracking, and the cracks are easy to expand, resulting in rapid failure of the mold

In addition, harmful elements such as P, Sn, and Sb in the steel mainly segregate at the grain boundary, making the grain boundary brittle, and cracks propagate along the brittle grain boundary, which also accelerates the occurrence of early fracture of the mold, further affecting the mold life

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