[0071] Example 2
[0072] The preparation method of the anti-vibration bar in the above embodiment 1 includes the following steps in sequence: induction furnace smelting, melting analysis, forging, hot rolling, first heat treatment, performance test (tensile, hardness) and metallographic inspection, product Analysis, cold drawing, second heat treatment, finished product processing, performance test (tensile, hardness) and grain size inspection, size inspection, marking, cleaning.
[0073] Said induction furnace smelting: when alloy materials are smelted, nickel plates, pure iron, and metallic chromium are placed at the bottom of the induction furnace and mixed and compacted. After 70% melting, 2% of the total feed weight is added for steelmaking. When the temperature of the molten steel reaches the tapping temperature, the molten steel is poured into the ladle, calmed for 1-2 minutes, and then poured into ingots and bars. The weight of each ingot is 40-50kg, and the diameter of the ingot is 140mm small and 155mm large.
[0074] The smelting analysis includes: (1) Sampling: taking a chemical analysis sample by car or planing out of the range of 20mm from the ingot head and tail; (2) Taking a chemical analysis sample for each furnace number to determine the chemical composition of each furnace steel, And filter according to content standard data. The smelting chemical composition should meet the requirements of the following table:
[0075] Grade C Mn P S Si Cr Ni Fe Al 405 ≤0.08 ≤1.00 ≤0.040 ≤0.030 ≤1.00 11.5~14.5 ≤0.60 margin 0.10-0.30
[0076] Said forging: forging the steel ingots that have passed the analysis at 1150-1220°C into a steel billet with a size of 50*50mm;
[0077] (1) Forging heating temperature table:
[0078]
[0079] (2) Forging: forging compression ratio: 4-6; forging size: 50*50mm; billet big end is cut more than 100mm, small end cut more than 50mm; forging billet surface treatment: forging billet surface peeling and grinding, removing surface wrinkles and cracks Surface defects such as heavy leather.
[0080] Said hot rolling: the steel billet is hot rolled at a temperature of 1050-1100°C and rolled into a ф16mm bar. After the hot rolling is cooled, the surface quality of the cracks, folds, scars, and inclusions must be inspected one by one, and thoroughly Polished clean
[0081] (1) The billet heating temperature table is as follows:
[0082]
[0083] (2) Rolling: The adjuster should straighten the appearance of the rolled product and roll it into a ф16mm wire; after the rolled product is cooled, the surface quality of the cracks, folds, scars, inclusions should be checked one by one, and the surface quality should be thoroughly polished. ; Rolling ratio: ≥5.
[0084] The first heat treatment: vacuum annealing the hot-rolled bar, keeping the temperature at 800±10°C;
[0085]
[0086] The performance test includes: (1) Take any set of samples for each batch of hot-rolled bars after heat treatment; (2) Perform tensile test, hardness test, metallographic analysis and product analysis on the samples respectively, Exclude substandard products;
[0087] performance Room temperature 350℃ Specified strength Rp0.2 (Mpa) ≥170 ≥145 Tensile strength Rm(Mpa) ≥415 ≥370 Elongation after breaking A (%) ≥20 info Reduction of area Z (%) ≥45 info
[0088] When the bar is ≤25mm, the longitudinal axis of the sample is consistent with the center of the bar, and the distance between the useful part of the sample and the heat-treated end of the bar shall not be less than the diameter of the bar.
[0089] performance Room temperature Hardness (HB) ≤207
[0090] The hardness test shall check the hardness of the bar at the middle of the distance from the center of the bar to the surface.
[0091] 3. Metallographic analysis should meet:
[0092]
[0093] 4. Product analysis: take samples at both ends of the tensile sample for material product analysis. The analysis results should meet:
[0094]
[0095] 5. Retest and re-heat treatment:
[0096] 5.1 If the tensile test results of the bar do not meet the requirements, two additional specimens can be cut from the adjacent part of the unqualified specimen for tensile test, and acceptance can only be accepted when the test results of the two additional specimens meet the requirements;
[0097] 5.2 If any batch of bars is improperly heat-treated and the mechanical properties are unqualified, the batch of materials can be re-heated, but the number of re-heat treatments should not exceed twice; after re-heat treatment, all the batches of materials specified in the technical conditions Inspection (except the inspection of chemical composition and non-metallic inclusions); all inspections shall meet the requirements of this technical specification.
[0098] The cold drawing includes: (1) first softening annealing treatment, holding at a temperature of 720-750°C for 40 minutes; (2) drawing with a polycrystalline die according to the deformation requirements, and grinding the surface micro-cracks , After grinding to no defects, the next drawing can be carried out.
[0099] The drawing deformation during cold drawing is φ16→φ14→φ12.5→φ11→4.8×12.8→4.4×12.5→4.028×12.19.
[0100] Steel type specification Heating temperature℃ Holding time (minutes) cooling method SA-479 TYPE405 Before each cold drawing 720-750℃ ≥40 Air cooling
[0101] The second heat treatment: spread the finished material flat in a bell-jar type heat treatment furnace, and conduct heat treatment under hydrogen protection. The annealing temperature is 788-815°C. The heat treatment temperature and other requirements are as follows:
[0102]
[0103] Said finished product processing: cold working procedures such as straightening and polishing the heat-treated bar, the thickness, width, twist, straightness and other dimensions after processing should meet the requirements of the following table:
[0104]
[0105] Said performance test: mechanical performance test, hardness test, and grain size inspection are performed on the bars, and the bars that do not meet the requirements of the technical conditions are excluded.
[0106] performance Room temperature Specified strength Rp0.2 (Mpa) 240-550 Tensile strength Rm(Mpa) 415-585 Elongation after breaking A (%) ≥15
[0107] performance Room temperature hardness HB≤207 or HRB≤93
[0108] Testing method Level requirements ASTM E112 Level 5 or finer
[0109] If the mechanical properties of the bar do not meet the technical requirements, double sampling can be carried out in the vicinity of the sample for retest, and the retest results should meet the technical requirements.
[0110] The dimensional inspection includes: (1) Visual inspection: visually inspect the surface of each material to be free of defects such as cracks and scratches. The bars are not allowed to undergo any welding repairs, and their surface roughness is gradually increased. In addition, the suspicious area needs to be inspected, and the measured result should be Ra≤1.6μm; (2) Dimensional inspection: 5% of the material is selected for dimensional inspection to ensure that the material size meets the tolerance requirements of 4.028±0.013*(12.19).
[0111] Said mark: each material should be accurately marked or attached with a label, indicating the name of the manufacturer, material brand and specification; melting furnace number, batch number and part number; contract number or order number.
[0112] Described cleaning: clean the bars according to relevant regulations to ensure that the surface of the finished bars is free of rust spots, dust and other contaminants; the steel bars cannot touch materials that are harmful to their integrity and integrity. The main metal incompatible materials include lead, zinc, copper, aluminum, cadmium, tin, mercury, sulfur, arsenic, boron and general low melting point alloys and their compounds. In addition, due to the The fluoride, sulfate, chloride and acid chloride produced by degradation are a potential hazard. Tapes, markers, coupling agents, penetrants and coatings should be carefully selected; if you want to use sanding tools, first make sure to sand the tools Not contaminated.