CN105714061A - Method for improving low-temperature impact toughness of 30CrNi2MoV steel forging - Google Patents
Method for improving low-temperature impact toughness of 30CrNi2MoV steel forging Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
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- C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
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- C—CHEMISTRY; METALLURGY
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- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
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Abstract
一种提高30CrNi2MoV钢锻件低温冲击韧性的方法,其特征是：先将锻造后的钢锻件进行常规奥氏体化处理，再将钢锻件随炉降温至Ac3温度附近，接着进行二次加热至780℃~810℃并保温2h±0.5 h，然后再进行淬火和最终的回火。本发明晶粒尺寸细化；可以在大提高30CrNi2MoV钢锻件低温冲击韧性的同时，对室温抗拉强度和室温延伸率影响不大。本发明可满足我国火电、核电等电站装备和大型冶金、矿山和运输装备中的大型承力和传动结构部件的制造需求。
A method for improving the low-temperature impact toughness of 30CrNi2MoV steel forgings, which is characterized in that: first, the forged steel forgings are subjected to conventional austenitization treatment, and then the steel forgings are cooled to around the Ac 3 temperature with the furnace, and then reheated to 780 ℃ ~ 810 ℃ and heat preservation for 2h ± 0.5h, and then quenching and final tempering. The grain size of the present invention is refined; while greatly improving the low-temperature impact toughness of 30CrNi2MoV steel forgings, it has little influence on room temperature tensile strength and room temperature elongation. The invention can meet the manufacturing requirements of large-scale load-bearing and transmission structural components in thermal power, nuclear power and other power station equipment and large-scale metallurgy, mining and transportation equipment in China.
Description
技术领域 technical field
本发明涉及一种金属热处理方法，尤其是一种30CrNi2MoV钢的热处理方法，具体地说是一种通过在Ac3温度附近增加加热保温工序的方法来提高30CrNi2MoV钢锻件低温冲击韧性。 The invention relates to a metal heat treatment method, especially a heat treatment method for 30CrNi2MoV steel, specifically a method for improving the low - temperature impact toughness of 30CrNi2MoV steel forgings by adding a heating and heat preservation process near the Ac3 temperature.
背景技术 Background technique
30CrNi2MoV钢是一种中碳中合金钢，具有高的淬透性和良好的综合力学性能，常用于制造高强韧性的大型（重量一般在4吨以上）锻件，广泛用于制造火电、核电等电站装备和大型冶金、矿山和运输装备中的承力和传动结构部件。 30CrNi2MoV steel is a medium-carbon medium-alloy steel with high hardenability and good comprehensive mechanical properties. It is often used to manufacture large-scale (generally weighing more than 4 tons) forgings with high strength and toughness. It is widely used in the manufacture of thermal power, nuclear power and other power stations. Bearing and transmission structural components in equipment and large metallurgy, mining and transportation equipment.
30CrNi2MoV钢常在较低温度下工作，对其低温冲击韧性有较高的要求。一般地，钢铁材料的奥氏体化工艺是影响其淬火回火后性能的重要因素。亚温淬火可以提高钢铁材料的低温冲击韧性，但提高低温冲击韧性的亚温淬火通常是在正常淬火后进行，这里正常淬火的目的是通过其较高温度的奥氏体化处理使钢铁材料的成分、组织均匀化，而后续亚温淬火则通过其产生的组织细化、少量铁素体的保留等提高钢铁材料的低温冲击韧性和强度。但是，这种正常淬火+亚温淬火提高钢铁材料低温冲击韧性的方法，涉及二个独立的淬火，工艺相对复杂，成本相对较高。如能通过常规奥氏体化+降温至Ac3温度附近继续加热然后淬火的一步处理提高钢铁材料的低温冲击韧性，无疑具有工艺相对简单、成本相对较低的优点。 30CrNi2MoV steel often works at lower temperatures, and has higher requirements for its low-temperature impact toughness. Generally, the austenitization process of steel materials is an important factor affecting their properties after quenching and tempering. Sub-temperature quenching can improve the low-temperature impact toughness of steel materials, but sub-temperature quenching to improve low-temperature impact toughness is usually carried out after normal quenching. The purpose of normal quenching here is to make the steel material toughness The composition and structure are homogenized, and the subsequent sub-temperature quenching improves the low-temperature impact toughness and strength of steel materials through the refinement of the structure and the retention of a small amount of ferrite. However, this method of normal quenching + sub-temperature quenching to improve the low-temperature impact toughness of steel materials involves two independent quenching processes, the process is relatively complicated, and the cost is relatively high. If the low-temperature impact toughness of steel materials can be improved through one-step treatment of conventional austenitization + cooling to Ac 3 temperature and then quenching, it will undoubtedly have the advantages of relatively simple process and relatively low cost.
至今为止，尚未有一种适合30CrNi2MoV钢的基于常规奥氏体化+降温至Ac3温度附近继续加热提高30CrNi2MoV钢低温冲击韧性方法可供使用，一定程度上限制了30CrNi2MoV钢的品质的提升和制造成本的下降。 So far, there has not been a method suitable for 30CrNi2MoV steel based on conventional austenitization + cooling to Ac 3 temperature to continue heating to improve the low-temperature impact toughness of 30CrNi2MoV steel, which limits the quality improvement and manufacturing cost of 30CrNi2MoV steel to a certain extent. Decline.
发明内容 Contents of the invention
本发明的目的是针对现有的工艺方法在提高30CrNi2MoV钢抗低温冲击韧性中存在的工艺复杂、成本高、难以推广的问题，发明一种基于增加Ac3温度（约815℃）附近加热工序来提高30CrNi2MoV钢锻件低温冲击韧性的方法。 The purpose of the present invention is to solve the problems of complex process, high cost and difficulty in promoting the existing process in improving the low-temperature impact toughness of 30CrNi2MoV steel, and to invent a method based on increasing the heating process near the Ac 3 temperature (about 815°C). A method to improve the low temperature impact toughness of 30CrNi2MoV steel forgings.
本发明的技术方案是： Technical scheme of the present invention is:
一种提高30CrNi2MoV钢锻件低温冲击韧性的方法,其特征是：先将锻造后的钢锻件进行常规奥氏体化处理，再将钢锻件随炉降温至Ac3温度附近，接着通过降温或进行二次加热至780℃~810℃并保温2h±0.5h，然后再进行淬火和最终的回火。 A method for improving the low-temperature impact toughness of 30CrNi2MoV steel forgings, which is characterized in that: firstly, the forged steel forgings are subjected to conventional austenitization treatment, and then the steel forgings are cooled to around the Ac 3 temperature with the furnace, and then by cooling or performing two Heating to 780℃~810℃ for the first time and holding for 2h±0.5h, then quenching and final tempering.
所述的Ac3温度附近加热工序，其特征是其最佳温度为780℃。 The heating process near the Ac 3 temperature is characterized in that its optimum temperature is 780°C.
本发明的有益效果： Beneficial effects of the present invention:
（1）本发明可以在显著提高30CrNi2MoV钢锻件的低温冲击韧性的同时，保持其抗拉强度变化不大。如以实施例一、实施例二与对比例一相比，晶粒尺寸细化，-40℃低温冲击韧性AKV(-40℃)提高了27.1~11.4%，室温抗拉强度提高了2.9~-6.9%、延伸率提高了-5.3~1.3%。 (1) The present invention can significantly improve the low-temperature impact toughness of the 30CrNi2MoV steel forging while maintaining little change in its tensile strength. For example, comparing Example 1 and Example 2 with Comparative Example 1, the grain size is refined, the low-temperature impact toughness A KV at -40°C (-40°C) is increased by 27.1~11.4%, and the tensile strength at room temperature is increased by 2.9~ -6.9%, elongation increased by -5.3~1.3%.
（2）本发明通过大量的试验获得了理想的基于在常规奥氏体化后增加降温至Ac3温度附近继续加热工序提高30CrNi2MoV钢锻件低温冲击韧性的方法，尤其是通过大量的试验获得了最佳的低温奥氏体化温度780℃，按本发明的工艺能容易地提高30CrNi2MoV钢锻件的低温冲击韧性。 (2) The present invention has obtained an ideal method for improving the low-temperature impact toughness of 30CrNi2MoV steel forgings based on increasing the temperature after conventional austenitization and continuing the heating process near the Ac 3 temperature through a large number of tests, especially through a large number of tests. The optimum low-temperature austenitization temperature is 780°C, and the low-temperature impact toughness of 30CrNi2MoV steel forgings can be easily improved by the process of the present invention.
（3）本发明在一定程度上打破了国外对大型锻件热处理工艺的技术封锁，可满足我国火电、核电等电站装备和大型冶金、矿山和运输装备中的大型承力和传动结构部件的制造需求。 (3) To a certain extent, the invention breaks the technical blockade of foreign countries on the heat treatment process of large-scale forgings, and can meet the manufacturing needs of large-scale load-bearing and transmission structural components in thermal power, nuclear power and other power station equipment and large-scale metallurgy, mining and transportation equipment in China .
附图说明 Description of drawings
图1实施例一：860℃′6h+780℃′2h油淬，600℃′16h油冷回火处理后的金相组织。 Figure 1 Example 1: Metallographic structure after oil quenching at 860°C'6h+780°C'2h, oil cooling and tempering at 600°C'16h.
图2实施例二：860℃′6h+810℃′2h油淬，600℃′16h油冷回火处理后的金相组织。 Figure 2 Example 2: Metallographic structure after oil quenching at 860°C'6h+810°C'2h, oil cooling and tempering at 600°C'16h.
图3对比例一：860℃′6h油淬，600℃′16h油冷回火处理后的金相组织。 Figure 3 Comparative Example 1: Metallographic structure after oil quenching at 860°C for 6 hours and oil cooling and tempering at 600°C for 16 hours.
具体实施方式 detailed description
下面对本发明的实施例作详细说明，本实施例在以本发明技术方案为前提下进行实施，给出了详细的实施方式和具体的操作过程，但本发明的保护范围不限于下述的实施例。 The embodiments of the present invention are described in detail below. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating procedures are provided, but the protection scope of the present invention is not limited to the following implementation example.
实施例一 Embodiment one
将30CrNi2MoV钢锻件加热至860℃保温6h，随炉降温至Ac3温度（约815℃）附近，接着再将炉温降至780℃保温2h，随后取出锻件进行油淬淬火；将经油淬淬火后的锻件从室温加热至600℃保温16h，取出锻件油冷至室温(晶粒尺寸如图1所示，比对比例晶粒尺寸如图3所示要小)。 Heat the 30CrNi2MoV steel forging to 860°C for 6 hours, cool down to Ac 3 temperature (about 815°C) with the furnace, then lower the furnace temperature to 780°C for 2 hours, then take out the forging for oil quenching; The final forging was heated from room temperature to 600°C for 16 hours, and the forging was taken out and cooled to room temperature (the grain size is shown in Figure 1, which is smaller than the grain size of the comparative example shown in Figure 3).
经如此热处理的30CrNi2MoV钢锻件，其在-40℃的低温冲击韧性AKV(-40℃)为40.3J，室温抗拉强度Rm为1043.6MPa，室温延伸率A5为35.65%。 The 30CrNi2MoV steel forging that has been so heat-treated has a low-temperature impact toughness A KV (-40°C) of 40.3J at -40°C, a room temperature tensile strength Rm of 1043.6MPa , and a room temperature elongation A5 of 35.65%.
实施例二 Embodiment two
将30CrNi2MoV钢锻件加热至860℃保温6h，降温至Ac3温度（约815℃）附近，接着再将炉温降至810℃保温2.5h，随后取出锻件进行油淬淬火；将经油淬淬火后的锻件从室温加热至600℃保温16h，取出锻件油冷至室温(晶粒尺寸如图2所示，比对比例晶粒尺寸如图3所示要小)。 Heat the 30CrNi2MoV steel forgings to 860°C for 6 hours, cool down to Ac 3 temperature (about 815°C), then lower the furnace temperature to 810°C for 2.5 hours, then take out the forgings for oil quenching; after oil quenching The forgings were heated from room temperature to 600 ° C for 16 hours, and the forgings were taken out and cooled to room temperature (the grain size is shown in Figure 2, which is smaller than that of the comparative example shown in Figure 3).
经如此热处理的30CrNi2MoV钢锻件，其在-40℃的低温冲击韧性AKV(-40℃)为35.3J，室温抗拉强度Rm为943.5MPa，室温延伸率A5为38.13%。 The 30CrNi2MoV steel forging that has been so heat-treated has a low-temperature impact toughness A KV (-40°C) of 35.3J at -40°C, a room temperature tensile strength Rm of 943.5MPa , and a room temperature elongation A5 of 38.13%.
实施例三 Embodiment Three
将30CrNi2MoV钢锻件加热至860℃保温6h，降温至Ac3温度（约815℃）附近，接着再将炉温降至795℃保温1.5h，随后取出锻件进行油淬淬火；将经油淬淬火后的锻件从室温加热至600℃保温16h，取出锻件油冷至室温(晶粒尺寸与图2相似，比对比例晶粒尺寸如图3所示要小)。 Heat 30CrNi2MoV steel forgings to 860°C for 6 hours, cool down to Ac 3 temperature (about 815°C), then lower the furnace temperature to 795°C for 1.5 hours, then take out the forgings for oil quenching; after oil quenching The forgings were heated from room temperature to 600°C and held for 16 hours, and the forgings were taken out and cooled to room temperature (the grain size is similar to that shown in Figure 2, but smaller than that of the comparative example shown in Figure 3).
经如此热处理的30CrNi2MoV钢锻件，其在-40℃的低温冲击韧性AKV(-40℃)为38.3J，室温抗拉强度Rm为983.5MPa，室温延伸率A5为37.13%。 The 30CrNi2MoV steel forging that has been so heat-treated has a low-temperature impact toughness A KV (-40°C) of 38.3J at -40°C, a room temperature tensile strength Rm of 983.5MPa , and a room temperature elongation A5 of 37.13%.
对比例一 Comparative example one
将30CrNi2MoV钢锻件加热至860℃保温6h，随后取出锻件进行油淬淬火；将经油淬淬火后的锻件从室温加热至600℃保温16h，取出锻件油冷至室温(晶粒尺寸如图3所示，比实施例晶粒尺寸如图1、2所示要大)。 Heat the 30CrNi2MoV steel forging to 860°C for 6 hours, then take out the forging for oil quenching; heat the forging after oil quenching from room temperature to 600°C for 16 hours, take out the forging and cool it to room temperature (the grain size is shown in Figure 3 Shown, bigger than embodiment grain size as shown in Figures 1 and 2).
经如此热处理的30CrNi2MoV钢锻件，其在-40℃的低温冲击韧性AKV(-40℃)为31.7J，室温抗拉强度Rm为1014.1MPa，室温延伸率A5为37.63%。 The 30CrNi2MoV steel forging that has been so heat-treated has a low-temperature impact toughness A KV (-40°C) of 31.7J at -40°C, a room temperature tensile strength Rm of 1014.1MPa , and a room temperature elongation A5 of 37.63%.
本发明未涉及部分均与现有技术相同或可采用现有技术加以实现。 The parts not involved in the present invention are the same as the prior art or can be realized by adopting the prior art.
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