Production process of high-cleanliness non-quenched and tempered plastic mold thick steel plate

Abstract

The invention relates to a production process of a high-cleanliness non-quenched and tempered plastic mold thick steel plate. The high-cleanliness non-quenched and tempered plastic mold thick steel plate is chemically composed of, by weight percentage, 0.25-0.45% of carbon, 0.20-0.50% of silicon, 0.70-1.50% of manganese, 0.70-2.00% of chromium, 0.15-0.55% of molybdenum, less than 0.01% of phosphorus, less than 0.005% of sulfur, 0.0010-0.030% of calcium, balanced iron and inevitable impurities. The chemical composition is simple in design; by means of the C-Mn-Cr-Mo alloying technology, the content of Mn and Cr can be improved;, by adding a certain amount of Mo, conversion of austenite to ferrite and pearlite can be inhibited, so that the high-cleanliness non-quenched and tempered plastic mold thick steel plate can have high hardenability and obtain a bainite structure; without the elements of Ti and V which are prone to generating inclusions, relatively clean steel can be obtained. The high-cleanliness non-quenched and tempered plastic mold thick steel plate has the advantages of being internally clean and compact, low in content of inclusions and capable of fundamentally eliminating pores, can meet the requirements of advanced plastic molds on internal high quality of steel and can be applied to the plastic mold industries such as automobile and electric appliances.

Description

[0001] technical field [0002] The invention belongs to the technical field of plastic mold steel, and relates to a production process of a high-clean non-quenched and tempered plastic mold steel thick plate. Background technique [0003] With the rapid development of my country's plastics industry, the service life of plastic molds, processing accuracy and the quality of plastic products are increasingly demanding, so higher requirements are put forward for inclusions and hole defects in the mold steel. High-end users generally require that the various ratings (ASTM) of inclusions should not be greater than 2.0, and the internal defects of ultrasonic flaw detection should be less than or equal to Φ2mm equivalent flat-bottomed holes. Therefore, it is an important topic to develop a high-clean non-quenched and tempered plastic mold steel production process with internal inclusions and less hole defects. [0004] The earlier production process of non-quenched and tempered ...

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Problems solved by technology

Its RH refining process has the ability to reduce the formation of oxides, but it has no ability to remove inclusions in molten steel; the measures to prevent the formation of secondary oxides in the continuous casting process are insufficient, and there are inevitably more inclusions in steel; the patent is in the rolling process , using controlled rolling technology, the single-pass reduction rate and cumulative reduction rate of the billet in the austenite recrystallization zone are unavoidably small, so the ability to compress the loose holes and internal cracks in the center of the billet is insufficient, and the internal holes of the steel plate There are inevitably many internal cracks; therefore, the ultrasonic inspection of the steel plate produced by this patent is qualified as the first level of the GB / T2970 standard, specifically, the length of a single internal defect is ≤80mm, which is far from meeting the requirements of ultrasonic flaw detection for internal defects ≤Φ2mm equivalent flat-bottomed holes

[0006] In short, the existing patented technology of non-quenched and tempered plastic mold steel production process is not capable of preventing central segregation, porosity, shrinkage cavity, and removal of inclusions in the process of smelting and continuous casting; The single-pass reduction rate and cumulative reduction rate are small, and the ability to press the loose holes and internal cracks in the center of the billet is insufficient

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