Oil Quenching And Tempering Alloy Spring Steel Wire65mn 60si2mna 55crsi SAE9254V 50crva

Oil quenching - tempering steel wire ProductsAbstract: This paper briefly introduces the characteristics of oil quenching-tempering steel wire, the current product standard, product development direction; and the production process and process control points, which provides useful information for the users to choose the steel wire grade and order quality products.Key words: oil quenching - tempering treatment, pre-hardening treatment, multiple tempering, on-line flaw detection.Special part of the steel products in the final need to quenching - tempering state, the traditional approach is to provide cold-drawn metal products factory annealing or state of the wire, the downstream enterprises will be made of steel wire parts or components, and then quenching + back Fire treatment, toughness to meet the scheduled requirements after delivery. Because the size of parts or components, shape ever-changing, bring the final heat treatment furnace vary widely, will inevitably lead to increased production costs, heat treatment performance fluctuations. Now gradually evolved into: the shape is not complex, easy processing of parts or components with wire quenching and tempering treatment transferred to the fabricated metal products factory, which formed a new species - quenching - tempering steel wire.1. OverviewOil quenching - tempering: a wire that is drawn to the finished size and quenched and tempered in a continuous furnace. The unwound wire is first heated to full austenitizing temperature in a continuous furnace and then quenched by oil bath Martensite, and then through the continuous furnace tempering, to obtain the expected strength and toughness. Oil quenching - tempering steel wire straightness is good, the uniformity of mechanical properties, made of components or components only after low temperature stress treatment that can be used directly.Oil quenching and tempering heat treatment furnace is composed of tension releasing device, heating furnace, oil quenching tank, tempering furnace and wire take-up machine. Commonly used in carbon spring steel wire, alloy spring steel wire, elastic wire cloth, alloy structural steel wire and martensitic stainless steel wire and other finished heat treatment, heat treatment of steel wire microstructure usually tempered martensite, tempered martensite or Tempering sorbite, with high strength (hardness), the appropriate toughness and good straight performance.Pre-hardening treatment: is a special oil quenching - tempering treatment, refers to the steel wire drawing to the finished size after oil quenching, and then according to the grade and use, and then one or more high-temperature tempering treatment, the wire Hardness or tensile strength to meet the requirements of the corresponding level. Commonly used in cold work die steel, hot die steel wire and plastic mold steel wire and other finished heat treatment. Because such steel wire carbon and alloying elements are high, oil quenching - tempering must use some special technical measures:① to ensure the full dissolution of carbon and alloying elements, it is necessary to improve the austenitizing heating temperature (some up to 1150 ℃), to extend the holding time;② quenching after the steel wire retained austenite content, in order to promote the decomposition of Paralympic steel wire to ensure the predetermined hardness, must be used multiple tempering method, tempering holding time than the general tempering to extend several times to several hundred times.③ general quenching - tempering treatment, the purpose of tempering: to promote the transformation of martensite into tempered martensite, tempered sorbite, tempered sorbite or pearlite, tempering steel wire after the toughness and plasticity But the tensile strength and hardness must have a different range of decline. In the pre-hardening treatment, the tempering also has the purpose of promoting the transformation of the microstructure, but also has the effect of precipitation hardening. The Fe, Mn and alloying elements (Cr, Mo, Ti, V, W, Al, etc.) , Nitride or intermetallic compound (γ 'and γ' 'phase) precipitation, the steel wire can be done in toughness and plastic significantly improved at the same time, tensile strength and hardness no significant decline, or even improved.Special process requirements determine the pre-hardened equipment and general (spring steel) oil quenching - tempering equipment is very different: spring steel wire is usually selected for continuous oil quenching - tempering treatment, quenching furnace maximum operating temperature of 900 ℃, Back to the maximum temperature of 600 ℃ furnace, furnace length is relatively short. Hardening and quenching and tempering usually use a continuous furnace, but the maximum furnace temperature and furnace length are greatly improved. The world's advanced level of pre-hardening furnace, quenching furnace maximum temperature 1150 ℃, the effective heating zone length of 22m; tempering furnace maximum temperature of 700 ℃, the effective heating zone length of 30m. In addition, the retractable wire system can apply a certain wire, adjustable pre-tension, in order to improve the resistance to creep and stress relaxation properties of steel wire.In general, pre-hardening furnace can be used for oil quenching - tempering treatment, but the oil quenching - tempering furnace can not be used for pre-hardening treatment. The greater difference is that the pre-hardening treatment usually requires two or more tempering, the tempering holding time in hours, can not be completed in a continuous furnace, in the periodic annealing furnace, the manufacturer can Configuration of different specifications of the cyclical gas protection annealing furnace for the development of such steel wire and lay the foundation for the development.2. Oil quenching - tempering spring steel wireOil quenching - tempering spring steel wire microstructure for the uniform tempered martensite or tempered sorbite, isotropic, in the same tensile strength under the same conditions than the cold drawn steel wire has a higher elastic limit, there are Good straightness performance, anti-stress relaxation properties and creep resistance is better than cold-drawn steel wire; to ensure that relaxation rate ≤ 6.0%, the maximum working temperature of cold-drawn carbon steel wire is 120 ℃, oil quenching - tempering carbon The maximum operating temperature of the steel wire is 150 ℃, the maximum operating temperature of the 50CrV is 200 ℃, the maximum operating temperature of the 55CrSi and 60Si2MnA is 250 ℃, and the maximum working temperature of the 65Si2MnWA is 350 ℃. The use of oil quenching - tempered wire wound spring, the elimination of stress after tempering directly to use, simplifying the spring factory production process and reduce production costs; with the original system after quenching - tempering spring compared to the spring Surface decarburization and mechanical properties of uniformity has been fundamentally improved fatigue life with a few times to improve. At present, Japan's alloy steel wire standard, has been completely quenched with oil - tempering state to replace the cold-drawn state. China in recent years, large-scale oil quenching - tempered wire greatly replace the trend of cold-drawn steel wire. Oil quenching - tempering the shortcomings of the wire is improperly treated surface oxidation, decarburization heavier, affecting fatigue life; steel wire hydrogen embrittlement sensitivity, resistance to stress corrosion slightly worse.China's current standard GB / T18983-2003 "oil quenching and tempering spring steel wire" is the reference ISO / FDIS8458-3 drafted, since the date of implementation in 2003, instead of YB / T5008 (original GB2271) "valve oil quenching - tempering YB / T5103 (original GB / T4360-85) "oil quenching - tempering carbon spring steel wire", YB / T5103 (original GB / T4360-85) "oil quenching - tempering carbon Spring steel wire ", YB / T5104 (original GB / T4361-85)" oil quenching - tempering Si-Mn spring steel wire ", YB / T5105 original (GB / T5362-85) "Valve oil quenching - tempering Cr-Si alloy spring wire." The most advanced standard in the world is the new standard: EN 10270-2: 2011 (E) "Mechanical Spring Wire - Part 2: Oil Quenching - Tempering" issued by the European Committee for Standardization in October 2011 and formally implemented in April 2012 Spring steel ". Oil quenching - tempering spring steel wire commonly used brands and chemical composition as shown in Table 1.Table 1 chemical composition of the wire (melting analysis), mass fraction%GradesCSiMnCrVPSOther elementsStandardFDC (60～75Mn)0.60～0.750.10～0.350.50～1.20--≤0.030≤0.030Cu≤0.20GB/T18983      -2003TDC ,VDC (60～75Mn)0.60～0.750.10～0.350.50～1.20--≤0.020≤0.025Cu≤0.12GB/T18983      -200350CrVA (FDCrV-A,TDCrV-A)0.47～0.550.10～0.400.60～1.200.80～～1.100.15～0.20≤0.030≤0.030Cu≤0.20GB/T18983      -2003VDCrV-A(50CrVA)0.47～0.550.10～0.400.60～1.200.80～1.100.15～0.25≤0.025≤0.025Cu≤0.12GB/T18983      -200367CrVA (FDCrV-B,TDCrV-B)0.62～0.720.15～0.300.50～0.900.40～0.600.15～0.25≤0.030≤0.030Cu≤0.20GB/T18983      -2003VDCrV-B(67CrVA)0.62～0.720.15～0.300.50～0.900.40～0.600.15～0.25≤0.025≤0.025Cu≤0.12GB/T18983      -2003FDSiMn,TDSiMn      (60SiMn)0.56～0.641.50～2.000.60～0.90≤0.035≤0.035Cu≤0.25GB/T18983      -200355CrSiA      (FDCrSi,TDCrSI)0.50～0.601.20～1.600.50～0.900.50～0.80≤0.030≤0.030Cu≤0.20GB/T18983      -2003VDCrSi(55CrSiA)0.50～0.601.20～1.600.50～0.900.50～0.80≤0.025≤0.025Cu≤0.12EN10270-2：2011FDCrSiV(60CrSiVA)0.50～0.701.20～1.650.40～0.900.50～1.000.10～0.25≤0.030≤0.025Cu≤0.12EN10270-2：2011TDCrSIV(60CrSiVA)0.50～0.701.20～1.650.40～0.900.50～1.000.10～0.25≤0.020≤0.020Cu≤0.10EN10270-2：2011VDCrSiV(60CrSiVA)0.50～0.701.20～1.650.40～0.900.50～1.000.10～0.25≤0.020≤0.020Cu≤0.06EN10270-2：2011Medium and high fatigue life of steel wire v adjustable0.05～0.15.