原文：
1高压主汽调节阀修复方案 1．1阀碟导向凸肩工作机理 2号机组为东方汽轮机厂制造的（N300－16．7／537／537－3型）汽轮机，它的高压主汽调节阀是由1个主汽阀和2个调节阀组成，高压调节阀是用于调节高压缸的进汽量。机组运行时，油动机作为机械提升装置，使阀碟导向凸肩沿导向槽上下移动，控制调节阀碟的开度。机组运行时，调节阀的高温蒸汽为16．7MPa，537℃，导向凸肩主要承受热应力和一定的周向剪切应力作用。 1号高压调节阀的阀碟与阀座配合直径为170mm， 其阀碟的结构如图1所示，导向凸肩尺寸为55mm×30mm×10mm（高×宽×厚）。阀碟材料采用20Cr3MoWVA合金钢，为了提高阀碟耐汽蚀的性能，其表面进行过高温渗氮处理。 1．2堆焊材料和焊接设备的选择 根据调节阀的工作条件，阀碟导向凸肩既要保证有足够高温强度，又要满足一定的耐磨性。鉴于机组抢修，无法采购到{zj0}匹配材料，参照堆焊材料的选用原则以及对各堆焊材料力学性能的分析，选用与母材材质相近的TIG－R34（12Cr2MoWVTIB，Φ2．5mm）焊丝。焊接设备采用 LincolnV300－1及氩弧焊接配套工具；温度监控使用美国MX2红外线测温仪。 2焊接性能分析 根据碳当量公式计算，材料20Cr3MoWVA的主要特点是含碳及合金元素较多，焊接时焊缝及热处理区容易出现淬硬组织，当焊件刚性及接头应力较大时，容易产生冷裂纹。 经过渗氮处理的阀碟，其表面硬度高达HV900，焊接时极易产生裂纹。 3堆焊工艺 3．1工艺路线 焊前打磨清洗－预热－堆焊－焊后热处理－焊后车削。 3．2焊前准备 首先用角向砂轮打磨彻底清理去除堆焊部位20mm范围内的渗氮层，打磨深度应大于0．4mm，测量打磨部位的硬度值，并保证施焊区域达到HB185～321的要求。按JB4730－94检测标准，检查打磨后的导向凸肩表面质量不得有裂纹、夹渣等缺陷，达到Ⅰ级标准为合格。 然后用丙酮清洗阀碟焊接部位及其周围50mm范围内，保证无水、油等；用砂纸xx氩弧焊丝表面的油污和锈斑等脏物。 3．3焊接工艺及参数 采用氧乙炔火焰加热的方法进行焊前预热，预热温度为350～400℃，用测温仪测量预热温度。阀碟焊接部位露出，其它部位用石棉布包覆，避免电弧xx。工艺参数I＝80～90A，氩气流量8～10L／min，直流正接，电压范围10～15V，焊接速度30～45mm／min，每道摆动宽度≤10mm，每层堆焊厚度≤4mm。预热温度达到后开始焊接，层间温度控制在300～400℃，焊接过程中不允许产生任何缺陷，重点检查引、收弧处，发现缺陷立即用角向磨光机去除。为保证加工余量，按图堆焊尺寸，外径增加5mm，内径减少5mm，堆高13mm。一边堆焊完成后再堆焊另一边。 焊接完成后，用硅酸铝耐火棉包覆缓冷，焊接部位冷到100～150℃，立即进行焊后局部热处理。热处理采用火焰加热至640～660℃，保温30min，用测温仪监测，升温速度和冷却速度均＜300℃／h，冷却至300℃以下可不控制，冷却时用硅酸铝纤维毯包覆缓冷。 4焊后检验 按照工艺路线完成阀碟的堆焊和机械加工后，经渗透探伤和超声波探伤检查，焊缝没有裂纹、夹渣、气孔等缺陷质量，堆焊质量达到JB4730－94标准Ⅰ级的要求；在加工表面进行硬度测试，其平均硬度值为HB241， 与原母材的硬度值相近，满足工件的使用性能。 5结论 2号机组1号高压主汽调节阀焊接修复并运行近1年后，在机组大修时解体检查，堆焊的阀碟凸肩经5616h运行未发现任何问题。可见用TIG－R34氩弧焊丝堆焊20Cr3MoWVA材料采用预热350～400℃，焊后640～650℃，保温30min处理的焊接工艺是合理可行的。它不但解决了高压主汽调节阀正常对蒸汽进行调节，还节省了上万元资金。

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译文：
A high-pressure main steam valve repair program 1.1 The valve disc oriented shroud working mechanism Unit 2 is made Dongfang Steam Turbine Works (N300-16.7/537/537-3 type) steam turbine, its main steam pressure regulating valve is a main steam valve and two valves composed of high-pressure regulating valve is for regulating the high pressure steam into the cylinder. Unit is running, the oil motive as mechanical lifting devices, so that valve disc oriented shroud up and down along the guide slot, the control valve disc opening. Unit run-time, high temperature steam valve to 16.7MPa, 537 ℃, oriented shroud to withstand heat stress and certain major circumferential shear stress. 1, high pressure control valve with the valve disc and valve seat diameter of 170mm, the valve plate structure shown in Figure 1, oriented shroud size of 55mm × 30mm × 10mm (height × width × thickness). Valve disc material is 20Cr3MoWVA alloy steel plate in order to improve anti-cavitation valve performance, the surface temperature nitriding treatment conducted. 1.2 surfacing materials and welding equipment selection According to the working conditions of valve, valve plate oriented shroud must ensure that sufficient high temperature strength, but also satisfy some wear resistance. View of the repair crew, unable to purchase the best matching materials, the light of the principles of surfacing materials used and the mechanical properties of the surfacing material analysis, selection and base metal close to TIG-R34 (12Cr2MoWVTIB, Φ2.5mm) wire. Using welding equipment LincolnV300-1 and TIG Welding, supporting tools; temperature monitoring using the U.S. MX2 infrared thermometer. 2 welding performance analysis According to carbon equivalent formula, the material 20Cr3MoWVA the main characteristics of carbon and alloy elements in large, welding and heat treatment weld area prone to hardened tissue, when the welded joints rigid and the stress is large, easy to cold cracks. After nitriding the valve plate, the surface hardness up to HV900, welding cracks easily. 3 Surfacing Technology 3.1 Process Route Polished clean before welding - warm - Surfacing - - weld heat treatment after welding, turning. 3.2 welding preparation Grinding wheel with the angle to the first complete removal of surfacing parts of 20mm clearance within the nitrided layer, polishing depth should be larger than 0.4mm, measuring the hardness of grinding parts, and to ensure that the weld area to HB185 ~ 321 requirements. According to JB4730-94 test is to check the guiding shroud polished surface quality may have cracks, inclusions and other defects, to grade Ⅰ standards compliance. Then washed with acetone and around the valve plate welding parts within 50mm to ensure the water and oil; welding wire with sandpaper remove oil and rust and other surface dirt. 3.3 Welding Procedure and parameters Using the methods oxyacetylene flame heating preheating, preheating temperature of 350 ~ 400 ℃, the preheating temperature measurement with thermometer. Valve plate welded parts exposed, other parts of the cloth covered with stone, to avoid arc burn. Parameters I = 80 ~ 90A, argon gas flow rate 8 ~ 10L/min, DC is connected, voltage range 10 ~ 15V, welding speed 30 ~ 45mm/min, Every swing width ≤ 10mm, the thickness of each layer surfacing ≤ 4mm. After preheating temperature of welding, interpass temperature control in the 300 ~ 400 ℃, the welding process does not allow any defects, focusing on inspection guidelines, income Arc, found flaws with the angle grinder to remove immediately. To ensure the machining allowance, according to Figure surfacing size, diameter increased 5mm, diameter reduction 5mm, piled high 13mm. While surfacing surfacing after the completion of the other side. Welding is completed, cotton coated with aluminum silicate refractory slow cooling, cold welding position to 100 ~ 150 ℃, local heat treatment immediately after welding. Heat treatment using flame heated to 640 ~ 660 ℃, holding 30min, with the thermometer monitoring, heating rate and cooling rate were <300 ℃ / h, cooled to below 300 ℃ may from time to control, cooling slowly coated with ceramic fiber blanket cold. 4 weld inspection The process is complete line of welding and mechanical valve plate processed by penetrant inspection and ultrasonic flaw detection, weld without cracks, inclusions, porosity and other defects in the quality of welding quality to JB4730-94 standard requirements of grade Ⅰ; in the process surface hardness test, the average hardness value of HB241, the original base metal hardness similar performance to meet the workpiece. 5 Conclusion 2 Unit 1 main steam pressure regulating valve repair welding and running nearly a year after the disintegration of the unit overhaul, inspection, welding of the valve disc shroud run through 5616h not found any problems. Can be seen with the TIG-R34 argon arc welding wire welding 20Cr3MoWVA material is preheated 350 ~ 400 ℃, after welding, 640 ~ 650 ℃, heat welding 30min treatment is reasonable and feasible. It not only solves the main steam pressure regulating valve to adjust the normal steam, but also saves money on the yuan.