A ductile cast iron laser cladding material and a laser cladding method

Abstract

The application discloses a laser cladding material for nodular cast iron parts, and specific components and mass percentages of the laser cladding material are as follows: C: 0.03-0.05, Si: 1.50-2.00, B: 1.0-1.5, Cr: 17.5-19.5, Mo: 5.0-6.0, Ni: 34-36, Co: 0.3-0.5, Nb: 1.5-2.0, Ti: 0.5-1.0, and Fe: balance. Meanwhile, the application also discloses a laser cladding method, which comprises the following steps: 1, the nodular cast iron part is cleaned and detected by PT flaw detection; 2, the nodular cast iron part is heated to 100-150 DEG C; 3, the surface of the nodular cast iron part is subjected to laser cladding: single layer thickness is 1.2-1.5 mm, and the overlapping amount is 2.5 mm; 4, the nodular cast iron part is wrapped with an asbestos blanket and is subjected to heat preservation and slow cooling; and 5, the nodular cast iron part after laser cladding is detected by PT flaw detection. The laser cladding material for the nodular cast iron part is a low-cost iron-based alloy powder with plasticity and strength, can ensure that large nodular cast iron parts are not cracked during laser cladding, and the cladding layer has good wear resistance, corrosion resistance and high-temperature resistance; and the material cost is significantly reduced compared with a nickel-based material.

Description

Technical Field

[0001] This invention relates to materials and methods for laser cladding of ductile iron. Background Technology

[0002] Ductile iron is a high-strength cast iron material. Due to its excellent properties, it has been widely used in parts subjected to complex stresses, such as automobile engine blocks, cylinder heads, crankcases, steering gear housings, and gearbox housings. The spheroidal graphite obtained through spheroidizing and inoculation treatments in ductile iron effectively improves the mechanical properties of cast iron, particularly its plasticity and toughness, thus giving it higher strength than carbon steel. However, because ductile iron has a high carbon content of 3.0%–4.0%, surface strengthening and remanufacturing of ductile iron parts are prone to cracking, white cast iron, and hardened structures. Therefore, surface strengthening and remanufacturing of ductile iron parts has always been a challenge in the industry.

[0003] Most existing publicly available technologies use low-hardness nickel-based alloy powder for laser cladding of ductile iron. While this solves the cracking problem of ductile iron to some extent, it also has drawbacks such as high cost and low hardness of nickel-based alloys.

[0004] Patent CN 109628923 A discloses an iron-based alloy powder for laser cladding remanufacturing of ductile iron parts. The powder has a high carbon content of 0.8-1.2% and a Cr content of less than 12%. Its disadvantages are: first, the high carbon content makes it very easy for defects such as cracks to occur during the laser cladding process; second, although it ensures corrosion resistance through a high Ni content, its Cr content of less than 12% is not conducive to the oxide film performance under high temperature environment, resulting in insufficient high temperature oxidation resistance. Summary of the Invention

[0005] The problem to be solved by the present invention is to provide a laser cladding material for ductile iron parts. It is a low-cost iron-based alloy powder with both plasticity, toughness and strength, which ensures that the laser cladding of large ductile iron parts does not crack. At the same time, the cladding layer has good wear resistance, corrosion resistance and high temperature resistance, and the material cost is significantly reduced compared with nickel-based materials.

[0006] This invention discloses a laser cladding material for ductile iron castings, the specific composition and mass percentage of which are: C: 0.03-0.05, Si: 1.50-2.00, B: 1.0-1.5, Cr: 17.5-19.5, Mo: 5.0-6.0, Ni: 34-36, Co: 0.3-0.5, Nb: 1.5-2.0, Ti: 0.5-1.0, Fe balance.

[0007] Furthermore, the preferred composition by mass percentage of the laser cladding material is: C: 0.032, Si: 1.85, B: 1.1, Cr: 18, Mo: 5.1, Ni: 36, Co: 0.4, Nb: 1.62, Ti: 0.57, with Fe as the balance.

[0008] Furthermore, the preferred composition by mass percentage of the laser cladding material is: C: 0.038, Si: 1.74, B: 1.3, Cr: 19, Mo: 5.4, Ni: 36, Co: 0.4, Nb: 1.8, Ti: 0.7, with Fe as the balance.

[0009] Furthermore, the preferred composition by mass percentage of the laser cladding material is: C: 0.045, Si: 1.66, B: 1.4, Cr: 17.8, Mo: 5.8, Ni: 35, Co: 0.5, Nb: 1.9, Ti: 0.8, with Fe as the balance.

[0010] This invention discloses a laser cladding method for materials used in laser cladding of ductile iron parts, comprising the following steps: 1. Cleaning and performing PT (Potential Transformer) flaw detection on the ductile iron parts; 2. Heating the ductile iron parts to 100-150℃; 3. Performing laser cladding on the surface of the ductile iron parts: single layer thickness 1.2-1.5mm, overlap 2.5mm; 4. Wrapping the ductile iron parts with asbestos for heat preservation and slow cooling; 5. Performing PT flaw detection on the laser-clad ductile iron parts.

[0011] The advantages of the laser cladding material of this invention are: 1. Low C content improves ductility and toughness, making ductile iron castings less prone to cracking and other defects during laser cladding; 2. Cr content greater than 12% provides excellent high-temperature oxidation resistance; 3. Ni content greater than 30% provides excellent corrosion resistance and avoids white cast iron structure during cladding; simultaneously, the Ni content is significantly reduced compared to nickel-based alloys (Ni≥50), resulting in a substantial cost reduction; 4. The addition of Co improves strength and high-temperature oxidation resistance; 5. Nb and Ti refine grain size, enhancing strength and ductility and toughness. Therefore, the laser cladding material of this invention is a low-cost iron-based alloy powder that combines ductility, toughness, and strength, ensuring that large ductile iron castings do not crack during laser cladding, while the cladding layer has good wear resistance, corrosion resistance, and high-temperature resistance, and the material cost is significantly reduced compared to nickel-based alloys. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the appearance of the laser cladding material cladding layer of the present invention.

[0013] Figure 2 This is a PT flaw detection image of the cladding layer of the laser cladding material of this invention.

[0014] Figure 3This is a metallographic image of the cladding layer of the laser cladding material of the present invention. Detailed Implementation

[0015] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0016] Example 1

[0017] This invention discloses a material for laser cladding of ductile iron parts, the specific composition and mass percentage of which are: C: 0.03-0.05, Si: 1.50-2.00, B: 1.0-1.5, Cr: 17.5-19.5, Mo: 5.0-6.0, Ni: 34-36, Co: 0.3-0.5, Nb: 1.5-2.0, Ti: 0.5-1.0, Fe balance.

[0018] The preferred composition (by mass percentage) of the material used for laser cladding is as follows:

[0019] C: 0.032, Si: 1.85, B: 1.1, Cr: 18, Mo: 5.1, Ni: 36, Co: 0.4, Nb: 1.62, Ti: 0.57, Fe balance.

[0020] C: 0.038, Si: 1.74, B: 1.3, Cr: 19, Mo: 5.4, Ni: 36, Co: 0.4, Nb: 1.8, Ti: 0.7, Fe balance.

[0021] C: 0.045, Si: 1.66, B: 1.4, Cr: 17.8, Mo: 5.8, Ni: 35, Co: 0.5, Nb: 1.9, Ti: 0.8, Fe balance.

[0022] As can be seen from the above composition, the advantages of the laser cladding material of this invention are: 1. The low C content improves plasticity and toughness, making ductile iron castings less prone to cracks and other defects during laser cladding; 2. The Cr content is greater than 12%, providing excellent high-temperature oxidation resistance; 3. The Ni content is greater than 30%, offering excellent corrosion resistance and preventing white cast iron structures during cladding; simultaneously, the Ni content is significantly reduced compared to nickel-based alloys (Ni≥50), resulting in a substantial cost reduction; 4. The addition of Co improves strength and high-temperature oxidation resistance; 5. Nb and Ti refine the grain size, enhancing strength and plasticity / toughness. Therefore, the laser cladding material of this invention is a low-cost iron-based alloy powder that combines plasticity, toughness, and strength, ensuring that large ductile iron castings do not crack during laser cladding, while the cladding layer has good wear resistance, corrosion resistance, and high-temperature resistance, and the material cost is significantly reduced compared to nickel-based alloys.

[0023] Example 2

[0024] This invention discloses a laser cladding method for materials used in laser cladding of ductile iron parts, comprising the following steps: 1. Cleaning and performing PT (Potential Transformer) flaw detection on the ductile iron parts; 2. Heating the ductile iron parts to 100-150℃; 3. Performing laser cladding on the surface of the ductile iron parts: single layer thickness 1.2-1.5mm, overlap 2.5mm; 4. Wrapping the ductile iron parts with asbestos for heat preservation and slow cooling; 5. Performing PT flaw detection on the laser-clad ductile iron parts.

[0025] Step 2, preheating, is to reduce the temperature difference during cladding of the ductile iron parts, thereby preventing cracking. Step 4, wrapping the parts with asbestos for insulation and slow cooling, is to reduce stress and prevent cracking of the ductile iron parts.

[0026] After laser cladding of the material used in this invention, from: Figure 1 It can be seen that the cladding layer is smoothly formed; from Figure 2 It can be seen that there are no defects such as cracks on the surface of the cladding layer; from Figure 3 It can be seen that the cladding layer has no internal defects and is well bonded to the ductile iron matrix.

[0027] Therefore, the laser cladding material for ductile iron parts of the present invention can obtain a high-quality cladding layer with good forming, no defects such as cracks, and metallurgical bonding with the matrix through laser cladding. The cladding layer has good wear resistance, corrosion resistance and high temperature resistance, and the material cost is significantly reduced compared with nickel-based materials.

Claims

1. A laser cladding material for ductile iron parts, characterized in that: Its specific composition and mass percentage are as follows: C: 0.03-0.05%, Si: 1.50-2.00%, B: 1.0-1.5%, Cr: 17.5-19.5%, Mo: 5.0-6.0%, Ni: 34-36%, Co: 0.3-0.5%, Nb: 1.5-2.0%, Ti: 0.5-1.0%, Fe balance.

2. The laser cladding material for ductile iron parts according to claim 1, characterized in that: The composition by mass percentage of the laser cladding material is as follows: C: 0.032%, Si: 1.85%, B: 1.1%, Cr: 18%, Mo: 5.1%, Ni: 36%, Co: 0.4%, Nb: 1.62%, Ti: 0.57%, Fe balance.

3. The laser cladding material for ductile iron parts according to claim 1, characterized in that: The composition by mass percentage of the laser cladding material is as follows: C: 0.038%, Si: 1.74%, B: 1.3%, Cr: 19%, Mo: 5.4%, Ni: 36%, Co: 0.4%, Nb: 1.8%, Ti: 0.7%, Fe balance.

4. The laser cladding material for ductile iron parts according to claim 1, characterized in that: The mass percentage composition of the laser cladding material is: C: 0.045%, Si: 1.66%, B: 1.4%, Cr: 17.8%, Mo: 5.8%, Ni: 35%, Co: 0.5%, Nb: 1.9%, Ti: 0.8%, Fe balance.

5. A laser cladding method for laser cladding materials used in ductile iron castings, characterized in that: It includes the following steps:

1. Clean and perform PT flaw detection on the ductile iron parts; 2. Heat the ductile iron parts to 100-150℃; 3. Perform laser cladding on the surface of the ductile iron parts: single layer thickness 1.2-1.5mm, overlap 2.5mm; 4. Wrap the ductile iron parts with asbestos for heat preservation and slow cooling.

5. Perform PT flaw detection on the ductile iron parts after laser cladding.

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