Casting production method of high-strength steel castings for coal mining machinery

Abstract

The invention relates to the technical field of casting, and provides a casting production method for high-strength steel castings of coal mining machinery. The material of the steel castings comprise the following elements by mass: 0.23 to 0.27 percent of C, 0.25 to 0.40 percent of Si, 1.00 to 1.20 percent of Mn, 0 to 0.015 percent of P, 0 to 0.010 percent of S, 0.5 to 0.6 percent of Cr, 0.30 to 0.4 percent of Mo, 0.6 to 0.9 percent of Ni, 0 to 0.030 percent of Sn, 0 to 0.005 percent of Sb, 0 to 0.002 percent of Pb, 0 to 0.03 percent of As, and the balance of Fe and unavoidable impurities, wherein Sn, Sb, Pb and As are residual elements; and the carbon equivalent Ceq of the material of the steel castings is 0.61 to 0.75. Smelting of the material of the steel castings adopts the technologies of EAF electric-furnace smelting, LF ladle refining and vacuum degassing VOD melting, so as to ensure that the oxygen activity in molten steel before discharging is equal to or smaller than 10 ppm, and the H content of the molten steel before discharging is smaller than 2 ppm. The molten steel of which the ingredients meet requirements after smelting is cast, steel castings obtained after casting are heated to 840 to 880 DEG C, the heated steel castings are quenched, the quenched steel castings are heated to 600 to 640 DEG C, and the reheated steel castings are tempered. According to the casting production method, the requirements of high strength, high plasticity and toughness, low deformation, and low cracking possibility on like castings can be met.

Description

technical field [0001] The invention relates to the technical field of casting, in particular to a casting production method of high-strength steel castings for coal mining machinery. Background technique [0002] The coal shearer is a large and complex system integrating machinery, electricity and hydraulic pressure. It works in a harsh environment with high impact and is impacted by ore for a long time. Therefore, the quality requirements for its supporting steel castings are relatively high. It is required that 100% of the castings be tested by magnetic particle testing (MT) and ultrasonic testing (UT). The surface of the castings is not allowed to have linear defects, shrinkage porosity, cold scars, cracks, etc. The requirements for mechanical properties and internal organization are very high, especially for equipment castings in high-end fully mechanized mining areas. If the shearer fails during work, it will cause the interruption of the entire coal mining work, resu...

AI Technical Summary

Problems solved by technology

Therefore, the deformation of the casting is small and it is not easy to crack, but the strength and hardness of the mechanical properties are low, which cannot meet the current high strength requirements.

If quenching is used, water or oil is usually used as the traditional quenching medium. Water quenching can meet the requirements of various mechanical properties, but the casting deformation is large and easy to crack; oil quenching, casting deformation is smaller than water quenching, and it is not easy to crack. , but the strength and hardness of the castings after oil quenching are lower than the lower limit, and the mechanical properties are prone to inconsistency. In addition, oil quenching will cause large oil fumes, easy to catch fire, and large environmental pollution. After quenching, the castings need to be cleaned before tempering, etc. , adding additional production costs