ASTM A350 specification covers several grades of carbon and low alloy steel forged or ring-rolled flanges, forged fittings and valves for low-temperature service. The steel specimens shall be melt processed using open-hearth, basic oxygen, electric furnace or vacuum-induction melting. A sufficient discard shall be made to secure freedom from injurious piping and undue segregation. The materials shall be forged and shall undergo heat treatment such as normalizing, tempering, quenching and precipitation heat treatment. Heat analysis and product analysis shall be performed wherein the steel materials shall conform to the required chemical compositions of carbon, manganese, phosphorus, sulfur, silicon, nickel, chromium, molybdenum, copper, columbium, vanadium, and nitrogen. The materials shall also undergo tension tests and shall conform to the required values of tensile strength, yield strength and elongation. Impact tests shall also be performed and the steel materials shall conform to the required values of minimum impact energy, temperature, and minimum equivalent absorbed energy. Hardness and hydrostatic tests shall also be performed.

ASTM A350规范涵盖了用于低温环境的几种等级的碳钢和低合金钢锻造或环轧法兰、锻造配件和阀门。钢试样应使用平炉、碱性氧气、电炉或真空感应熔炼进行熔融处理。应进行充分的丢弃，以确保没有有害的管道和不当的隔离。材料应锻造，并应进行正火、回火、淬火和沉淀热处理等热处理。应进行热分析和产品分析，其中钢材应符合碳、锰、磷、硫、硅、镍、铬、钼、铜、铌、钒和氮的所需化学成分。材料还应进行拉伸试验，并应符合抗拉强度、屈服强度和伸长率的要求值。还应进行冲击试验，钢材应符合最小冲击能量、温度和最小等效吸收能量的要求值。还应进行硬度和静水压试验。

ASTM A350 (ASME SA350) is the standard specification for carbon steel and low alloy steel forged flanges and flanged fittings for low temperature services.

Common use grade is ASTM A350 LF2 Class 1, corresponding material for piping in ASTM A333 Grade 6 and pipe fittings in ASTM A420 WPL6. With yield strength minimum 240 Mpa, and tensile strength in 480 Mpa to 655 Mpa, impact test temperature at -45℃.

ASTM A350（ASME SA350）是低温环境下碳钢和低合金钢锻造法兰和法兰配件的标准规范。

常用等级为ASTM A350 LF2 1级，相应的管道材料为ASTM A333 6级，管件材料为ASTM A420 WPL6。屈服强度最低为240 Mpa，抗拉强度为480 Mpa至655 Mpa，冲击试验温度为-45℃。

Scope

ASTM A350 covers several grades of carbon and low-alloy steel forged or ring-rolled flanges, forged fittings and valves intended primarily for low-temperature service and requiring notch toughness testing. They are made to specified dimensions, or to dimensional standards, such as the ASME and API Specifications referenced in Section 2. Although this specification covers some piping components machined from rolled bar and seamless tubular materials, it does not cover raw material produced in these product forms.

Product furnished in ASTM A350/ ASME SA350 shall conform to the requirements of Specification A961/A961M, including any supplementary requirements that are indicated in the purchase order. Failure to comply with A961/A961M will be considered nonconformance with A350. And in case of conflict between ASTM A350 and A961/A961M, this specification shall prevail.

ASTM A350涵盖了几种等级的碳钢和低合金钢锻造或环轧法兰、锻造配件和阀门，主要用于低温环境，需要进行缺口韧性测试。它们是按照规定的尺寸或尺寸标准制作的，如第2节中引用的ASME和API规范。虽然本规范涵盖了一些由轧制棒材和无缝管材加工而成的管道部件，但不包括以这些产品形式生产的原材料。

ASTM A350/ASME SA350中提供的产品应符合规范A961/A961M的要求，包括采购订单中指出的任何补充要求。不符合A961/A961M将被视为不符合A350。如果ASTM A350和A961/A961M之间存在冲突，应以本规范为准。

ASTM A350 Chemical composition requirements

*1. When vacuum carbon-deoxidation is required, the silicon content shall be 0.12% maximum.
*2. For grades LF1, LF2 & LF6, the sum of Cu, Ni, Cr, V and Mo shall not exceed 1.00 % on heat analysis.
*3. For all grades except grade LF787, the sum of Cr and Mo shall not exceed 0.32 % on heat analysis.
*4. For grades LF1 & LF2, the limit for Cb may be increased up to 0.05 % on heat analysis and 0.06 % on product analysis.
*5. The carbon equivalent C.E = [C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15] shall not exceed 0.45%.

*1.当需要真空碳脱氧时，硅含量最大为0.12%。

*2.对于LF1、LF2和LF6级，热分析中Cu、Ni、Cr、V和Mo的总和不得超过1.00%。

*3.对于除LF787以外的所有牌号，热分析中Cr和Mo的总和不得超过0.32%。

*4.对于LF1和LF2级，Cb的限值在热分析中可提高到0.05%，在产品分析中可增加到0.06%。

*5.碳当量C.E=[C+Mn/6+（Cr+Mo+V）/5+（Ni+Cu）/15]不得超过0.45%。

ASTM A350 mechanical properties

*1. The elongation values are on the basis of standard round specimen, or small proportional specimen, min % in 4D gauge length.
*2. The yield strength shall be determined by either the 0.2 % offset method or the 0.5 % extension under load method.

*1.伸长率值基于标准圆形试样或小比例试样，4D标距长度中的最小百分比。

*2.屈服强度应通过0.2%偏移法或0.5%负载延伸法确定。

Mechanical Properties

Tension Tests Requirements—The material shall conform to requirements for tensile properties in below table.

Heat Analysis and Product Analysis

A chemical heat analysis and product analysis in accordance with Specification A961/A961M shall be made and conform to the requirements as to chemical composition prescribed in this table. Leaded steels shall not be permitted. Product analysis

Heat Treatment & Welding Process

As specified by ASTM A350, after hot working and before reheating for heat treatment, the forging shall be allowed to cool substantially below the transformation range. Forgings of grades other than Grade LF787 shall be furnished in the normalized, or normalized and tempered, or quenched and tempered condition. All quenched forgings shall be then tempered at 1100 °F [590 °C], minimum, holding at temperature a minimum of 30 min/in. [30 min/25 mm] of maximum thickness, but in no case less than 30 min. Grade LF787 forgings shall be furnished in either the normalized-and-precipitation heat treated condition or in the quenched-and-precipitation heat treated condition.

For Grade LF1 and LF2 forgings, the weld metal shall be deposited using carbon steel electrodes E 7015, E 7016, or E 7018, complying with AWS A 5.1. For Grade LF2 forgings, the weld metal shall be deposited using low-alloy steel electrodes E 7015-A1; E 7016-A1, or E 7018-A1 complying with AWS 5.5; for Grade LF3 forgings, the weld metal shall be deposited using low-alloy steel electrodes E 8016-C2 or E 8018-C2 complying with AWS A 5.5; for Grades LF5, LF9, and LF787 forgings, the weld metal shall be deposited using low-alloy steel electrodes E 8016-C1 or E 8018-C1 complying withAWS A 5.5. For Grade LF6, the electrodes shall be low-hydrogen, E-XX15, E-XX16, or E-XX18 complying with AWS A 5.1 or A 5.5, as applicable.

机械性能

拉伸试验要求——材料应符合下表中的拉伸性能要求。

热分析和产品分析

应按照规范A961/A961M进行化学热分析和产品分析，并符合本表规定的化学成分要求。不允许使用含铅钢。产品分析

热处理和焊接工艺

根据ASTM A350的规定，在热加工后和重新加热进行热处理之前，应允许锻件冷却到相变范围以下。LF787级以外的锻件应在正火、正火和回火或淬火和回火状态下提供。然后，所有淬火锻件应在最低1100°F[590°C]的温度下回火，保持最小30分钟/英寸[30分钟/25毫米]的最大厚度，但在任何情况下不得低于30分钟。LF787级锻件应在正火和沉淀热处理条件下或淬火和沉淀热处理条件下提供。

对于LF1和LF2级锻件，应使用符合AWS A 5.1的碳钢焊条E 7015、E 7016或E 7018沉积焊接金属。对于LF2级锻件，应使用低合金钢焊条E 7015-A1沉积焊缝金属；符合AWS 5.5的E 7016-A1或E 7018-A1；对于LF3级锻件，应使用符合AWS A 5.5的低合金钢焊条E 8016-C2或E 8018-C2沉积焊接金属；对于LF5、LF9和LF787级锻件，应使用符合AWS A 5.5的低合金钢焊条E 8016-C1或E 8018-C1沉积焊接金属。对于LF6级，电极应为符合AWS A 5.1或A 5.5（如适用）的低氢、E-XX15、E-XX16或E-XX18。

The dimensional standards for ASTM A350 forgings

Referenced Documents

ASTM Standards:

• A788/A788M Specification for Steel Forgings, General Requirements钢锻件规范，一般要求
• A961/A961M Specification for Common Requirements for Steel Flanges, Forged Fittings, Valves, and Parts for Piping Applications管道用钢法兰、锻造配件、阀门和零件的通用要求规范

ASME Standards:

• B 16.5 Steel Pipe Flanges and Flanged Fittings钢管法兰和法兰配件
• B 16.9 Factory-Made Wrought Steel Butt-Welding Fittings工厂制造的锻钢对接焊接配件
• B 16.10 Face-to-Face and End-to-End Dimensions of Ferrous Valves铁质阀门的面对面和端到端尺寸
• B 16.11 Forged Steel Fittings, Socket-Welding and Threaded承插焊和螺纹锻钢配件
• B 16.30 Unfired Pressure Vessel Flange Dimensions非受火压力容器法兰尺寸
• B 16.34 Valves-Flanged, Threaded, and Welding End法兰、螺纹和焊接端的阀门
• B 16.47 Large Diameter Steel Flanges大直径钢法兰
• ASME Boiler and Pressure Vessel Code锅炉和压力容器规范

AWS Standards:

• A 5.1 Mild Steel Covered Arc-Welding Electrodes低碳钢焊条
• A 5.5 Low-Alloy Steel Covered Arc-Welding Electrodes低合金钢焊条

API Standards:API标准

• 600 Steel Gate Valves with Flanged or Butt-Welding Ends法兰或对焊端钢制闸阀
• 602 Compact Design Carbon Steel Gate Valves for Refinery Use炼油厂用紧凑型碳钢闸阀
• 605 Large Diameter Carbon Steel Flanges大直径碳钢法兰

Manufacture – Melting and Forging制造-熔化和锻造

Melting Process – The steel shall be produced by any of the following primary processes: open-hearth, basic oxygen, electric-furnace, or vacuum-induction melting (VIM). The primary melting may incorporate separate degassing or refining, and may be followed by secondary melting using electroslag remelting (ESR), or vacuum-arc remelting (VAR).

Discard – A sufficient discard shall be made to secure freedom from injurious piping and undue segregation.

Forging Process

Material for forgings shall consist of ingots, or forged, rolled, or strand cast blooms, billets, slabs, or bars.

制造-熔化和锻造

熔炼工艺——钢材应通过以下任何一种主要工艺生产：平炉、碱性氧气、电炉或真空感应熔炼（VIM）。一次熔化可以包括单独的脱气或精炼，然后可以使用电渣重熔（ESR）或真空电弧重熔（VAR）进行二次熔化。

丢弃——应进行充分的丢弃，以确保没有有害的管道和不当的隔离。

锻造工艺

锻件材料应由铸锭、锻造、轧制或铸坯、钢坯、板坯或棒材组成。

Heat Treatment热处理

After hot working and before reheating for heat treatment, the forging shall be allowed to cool substantially below the transformation range.

Forgings grades except Grade LF787, should be heat treated in normalized, or normalized and tempered, or quenched and tempered. By manufacturer’s option, material that performed in quenched and tempered could be normalized prior to the austenitize/quenched operation.

No limitation on size is intended beyond the ability of the manufacturer to obtain the specified requirements. However, Class 3 of Grade LF787 is only available in the quenched-and-precipitation heat treated condition.

热加工后，在重新加热进行热处理之前，应允许锻件冷却到相变范围以下。

除LF787级外的锻件等级应进行正火、正火和回火或淬火和回火热处理。根据制造商的选择，在奥氏体化/淬火操作之前，可以对淬火和回火的材料进行正火处理。

制造商获得规定要求的能力之外，不打算对尺寸进行任何限制。然而，LF787级的3级仅在淬火和沉淀热处理条件下可用。

Hydro-static Test水压试验

Forgings manufactured under ASTM A350/ ASME SA350 shall be performed with a hydro-static test compatible with the rating of the finished item. Such tests shall be conducted by the manufacturer only when Supplementary Requirement S57 of Specification A961/A961M is specified.

根据ASTM A350/ASME SA350制造的锻件应进行与成品额定值兼容的静水压试验。只有在规定了规范A961/A961M的补充要求S57时，制造商才能进行此类测试。