High rpc value work roll for cold rolling of aircraft aluminum sheet and method of making same

Abstract

The application discloses a high Rpc value work roll for aviation aluminum plate cold rolling and a manufacturing method thereof, wherein a final heat treatment adopts a superfine heat treatment process of superfast heating and superfast cooling, the superfast heating adopts a double-frequency continuous induction quenching process, a power frequency coil heating temperature is controlled in a range of 900-950 DEG C, a medium frequency coil heating temperature is controlled in a range of 950-1000 DEG C, and a roll quenching moving speed is 0.5-0.8 mm / s; the superfast cooling adopts a strong spray cooling and water tank circulating cooling process; the strong spray cooling water pressure is 0.4-0.6 MPa, and the water tank circulating cooling water temperature is below 20 DEG C. The work roll body surface hardness prepared by the application is above 100 HSD, the hardness uniformity is less than or equal to 1 HSD, the grain size reaches more than 10 levels, and the Rpc value can reach 150 cm under the condition that the grinding roughness is Ra0.4+ / -0.05 microns. ‑1 The above.

Description

Technical Field

[0001] This invention belongs to the field of cold rolling work roll technology, specifically relating to a high Rpc value work roll for cold rolling of aerospace aluminum plates and its manufacturing method. Background Technology

[0002] High-precision cold-rolled aerospace aluminum sheets must possess excellent formability and paint adhesion. Among these requirements is the roughness peak count (Rpc, measured in cm). -1 Rpc (Residual Peaks Per Scale) is a key indicator for measuring the density of microscopic peaks on the surface of steel sheets. A higher Rpc value means that there are dense and uniform microscopic peaks and valleys on the surface. During subsequent spraying, the dense peaks and valleys can provide sufficient physical anchors, allowing the paint to adhere more firmly. If the Rpc value is low and uneven, orange peel, uneven gloss, or even paint peeling may occur after spraying. Secondly, to meet the strict sheet metal forming process, uniform sheet surface characteristics are required to ensure consistent metal flow under pressure and avoid cracking and wrinkling caused by local stress concentration or uneven lubrication. In addition, the "oil reservoir" formed by a high Rpc value can store more lubricant during forming, reduce friction, and prevent mold scratches.

[0003] The core of a high Rpc value lies in pressing dense and uniform micro-peaks onto the aluminum plate. This requires the roll to possess high hardness and high uniformity, and to achieve a high Rpc value under specific grinding roughness conditions. High hardness is essential to clearly imprint the micro-peaks and valleys of the roll surface onto the aluminum plate; if the hardness is insufficient, the micro-edges on the roll surface will collapse, leading to a decrease in the Rpc value of the aluminum plate. Therefore, the roll needs to maintain extremely high hardness throughout its entire life cycle. Secondly, the grain size of the roll must be strictly controlled to achieve an extremely fine microstructure, which allows for the acquisition of more micro-peak and valley structures during grinding. In addition, the roll needs to possess both excellent wear resistance and roughness retention properties to ensure the retention of the roll surface's micro-peaks during rolling. This requires achieving high wear resistance through special strengthening mechanisms.

[0004] Currently, conventional Cr5 material work rolls can achieve the required surface hardness through special heat treatment processes, but the hardness decays relatively quickly. Furthermore, the Rpc value of conventional Cr5 material work rolls at specific grinding roughnesses (e.g., Ra 0.4 ± 0.05 μm) is generally only 120 cm⁻¹. -1 It's difficult to reach 150cm. -1 The above requirements cannot meet the needs of high-grade aerospace aluminum sheet rolling throughout its entire life cycle. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems and provide a grinding surface roughness of Ra0.4±0.05μm with an Rpc value of 150cm. -1 The above describes high Rpc value work rolls for cold rolling of aerospace aluminum plates and their manufacturing methods.

[0006] The technical solution to achieve the purpose of this invention is: a method for manufacturing high Rpc value work rolls for cold rolling of aerospace aluminum plates, including smelting and forging roll blanks according to chemical composition and weight percentage, preheating treatment and final heat treatment.

[0007] The final heat treatment is a key factor in achieving a high Rpc value. By designing and developing an ultra-fine heat treatment process technology that combines ultra-fast heating and ultra-fast cooling, ultra-fine grain size can be achieved, thereby obtaining a high Rpc value.

[0008] The ultra-fast heating process employs a dual-frequency continuous induction hardening process, wherein the power frequency coil heating temperature is controlled at 900–950℃, the medium frequency coil heating temperature is controlled at 950–1000℃, and the roll quenching moving speed is 0.5–0.8 mm / s.

[0009] The ultra-fast cooling adopts a strong spray cooling + water tank circulation cooling process. The water pressure of the strong spray cooling is 0.4 to 0.6 MPa, and the water tank circulation cooling precisely controls the circulating water temperature to below 20°C.

[0010] After quenching, the material is directly placed in a cryogenic treatment tank and held at -130 to -170°C for 5 to 8 hours to undergo further microstructural transformation. Finally, a long-term heat treatment process is adopted.

[0011] The temperature control range of the above-mentioned ultra-fine heat treatment process is relatively narrow. The chemical composition of the roll material, especially the alloy composition of chromium, nickel, molybdenum, vanadium and other alloys, needs to be strictly controlled. Otherwise, it will still be impossible to obtain a high Rpc value.

[0012] The chemical composition and weight percentages are as follows: carbon 0.95–1.00%, silicon 0.80–1.00%, manganese 0.40–0.60%, phosphorus ≤0.010%, sulfur ≤0.010%, chromium 4.90–5.00%, nickel 0.40–0.50%, molybdenum 0.50–0.60%, vanadium 0.20–0.30%, with the remainder being iron and unavoidable impurities.

[0013] The positive effects of this invention are as follows: This invention employs an ultra-fine heat treatment process for specific ranges of roll materials to obtain work rolls with a surface hardness of 100 HSD or higher and a hardness uniformity of ≤1 HSD. Simultaneously, the grain size of this work roll reaches grade 10 or higher, and with a grinding roughness of Ra0.4±0.05μm, its Rpc value can reach 150cm. -1 above. Detailed Implementation

[0014] (Example 1) The manufacturing method of the high Rpc value work roll for cold rolling of aerospace aluminum plates in this embodiment is as follows: ① Roll blanks are smelted and forged using conventional methods according to the following chemical composition and weight percentages: carbon 0.98%, silicon 0.90%, manganese 0.50%, phosphorus ≤0.010%, sulfur ≤0.010%, chromium 4.95%, nickel 0.45%, molybdenum 0.55%, vanadium 0.25%, with the remainder being iron and unavoidable impurities.

[0015] ②Preparatory heat treatment.

[0016] First, perform quenching and tempering treatment at 950±5℃ for 6 hours, then perform high-temperature tempering treatment at 620±5℃ for 20 hours.

[0017] ③ Final heat treatment.

[0018] The process employs a dual-frequency continuous induction hardening process, where the power frequency coil heating temperature is controlled at 920℃, the medium frequency coil heating temperature is controlled at 970℃, and the roll quenching moving speed is 0.6mm / s.

[0019] Then, a strong spray cooling + water tank circulation cooling process is adopted. The water pressure of the strong spray cooling is 0.5MPa, and the water tank circulation cooling precisely controls the circulating water temperature to below 20℃.

[0020] After quenching, the sample is directly placed in a cryogenic treatment bath and held at -150℃ for 6 hours, and finally tempered at 120±5℃ for 96 hours.

[0021] The surface hardness of the work roll body obtained in this embodiment is 101HSD, and the hardness uniformity is ≤1HSD.

[0022] The surface roughness of this embodiment is ground to Ra0.40μm, and its Rpc value can reach 164cm. -1 It can meet the high Rpc value retention requirements for high-end aerospace aluminum plate rolling.

[0023] (Examples 2-3) Each embodiment is basically the same as Embodiment 1, and the differences are shown in Table 1.

[0024] (Comparative Examples 1 to 2) Each comparative example is basically the same as Example 1, with the differences shown in Table 1.

[0025] Table 1 chromium 4.95% 4.90% 5.00% 4.70% 5.20% nickel 0.45% 0.40% 0.50% 0.25% 0.65% molybdenum 0.55% 0.50% 0.60% 0.35% 0.65% vanadium 0.25% 0.20% 0.30% 0.10% 0.40% Roller body surface hardness 101HSD 100.7HSD 101.2HSD 100HSD 101.5HSD Rpc value <![CDATA[164cm -1 ]]> <![CDATA[155cm -1 ]]> <![CDATA[157cm -1 ]]> <![CDATA[132cm -1 ]]> <![CDATA[137cm -1 ]]> .

Claims

1. A method for manufacturing a high Rpc value work roll for cold rolling of aerospace aluminum plates, comprising smelting and forging a roll blank according to chemical composition and weight percentage, preheat treatment, and final heat treatment; characterized in that: The final heat treatment employs an ultra-rapid heating + ultra-rapid cooling process for ultra-fine heat treatment. The ultra-rapid heating uses a dual-frequency continuous induction hardening process, with the power frequency coil heating temperature controlled at 900–950℃ and the medium frequency coil heating temperature controlled at 950–1000℃. The roll quenching moving speed is 0.5–0.8 mm / s. The ultra-rapid cooling uses a strong spray cooling + water tank circulation cooling process. The water pressure for the strong spray cooling is 0.4–0.6 MPa, and the water temperature for the water tank circulation cooling is below 20℃.

2. The method for manufacturing high Rpc value work rolls for cold rolling aerospace aluminum plates according to claim 1, characterized in that: The chemical composition and weight percentages are as follows: carbon 0.95–1.00%, silicon 0.80–1.00%, manganese 0.40–0.60%, phosphorus ≤0.010%, sulfur ≤0.010%, chromium 4.90–5.00%, nickel 0.40–0.50%, molybdenum 0.50–0.60%, vanadium 0.20–0.30%, with the remainder being iron and unavoidable impurities.

3. A high Rpc value work roll for cold rolling of aerospace aluminum plates, prepared by the method of claim 1 or 2.