Overview properties of ferrotungsten use quality specifications  

Iron tungsten  

1. Overview 

Ferrotungsten is an alloy of tungsten and iron. It is used in steelmaking and casting as an additive to the element tungsten, which is one of the most important alloying elements in the production of special steels. Tungsten can reduce the elongation of steel to a lesser extent, while improving the strength limit and yield point of steel, but also improve the hardness and wear resistance of steel. It is particularly important that tungsten has a good impact on the high-temperature mechanical properties of steel, which can improve heat resistance and tempering stability. The most common method of producing ferro-tungsten is the "block method", that is, the oxide in the concentrate is reduced with carbon in an electric furnace, and then the solidified metal blocks are removed from the furnace. There is also the iron digging method and the aluminothermal method. Ferrotungsten is a legal inspection commodity. The main production areas are Jiangxi, Hunan, Henan, etc., mainly exported to the Netherlands, Hong Kong and other regions.  

2. Physical state  

Ferro-tungsten is delivered in blocks, with a block size range of 10 to 130 mm, less than 10× 10 mm The amount of broken pieces should not exceed 5% of the total weight of the batch, allowing individual blocks to be 150 mm in one direction. The surface of the tungsten iron block should be smooth, and there is no significant non-metallic inclusion and rust spots on the section and surface.  

3. Grade and chemical composition  

According to the provisions of GB/T3648-96, ferrotungsten is divided into four grades according to the different content of tungsten and impurities, and its chemical composition should comply with the provisions of Table 6-6-21.  

If the demand side has special requirements for the table elements, it can be jointly negotiated by the supply and demand sides. When requested by the demander, it can negotiate to provide measured data for elements other than table columns.  

The required elements of ferrotungsten are the content of W, C, P, S, Si, mn, and the rest are guaranteed elements.  

4. Inspection standard  

(1) The quality inspection and acceptance of the product shall meet the requirements of GB/T3650-95 "General Provisions on Acceptance, Packaging, Storage and Transportation, Marking and Quality Certificate" of ferroalloy acceptance.  

(2) Group batch. Batch according to the furnace group method. The difference between the highest or lowest tungsten content and the average sample tungsten content in each batch of products shall not exceed 3%. It can also be batched according to the batch method, and a batch of delivered products is composed of several furnace tungsten iron of a grade. The difference in tungsten content between the furnaces that make up a batch of delivered products is not more than 3% (absolute value).  

(3) Sampling. The sampling of specimens for chemical analysis should be carried out in accordance with GB/T4010-94 "Specimens taken and prepared for ferroalloy chemical analysis".  

(4) Chemical analysis. The corresponding elements are tested according to the following methods: GB7731.1-87 Xinkonin gravimetric determination of tungsten amount; GB 7731.2—87 Determination of manganese by photometric method of sodium periodate; GB7731.3—87 Determination of copper amount of dicyclohexanone oxaloylacetone; GB7731.4—87 Determination of phosphorus by molybdenum blueness method; GB7731.5—87 Molybdenum blue light method for determination of silicon amount; GB7731.6—87 Molybdenum blue light degree method for determining arsenic volume; GB7731.7—87 Determination of tin amount by phenylfluorescent ketone spectrophotometry; GB7731.8—87 Rhodamine B-photometric determination of antimony; GB7731.9—87 Bismuth iodide spectrophotometric determination of bismuth; GB7731.10—87 Infrared method for determining carbon quantity; GB7731.11—87 Coulometric determination of carbon amount; GB7731.12—87 Infrared method to determine sulfur content; GB7731.13—87 Determination of sulfur by combustion neutralization method; GB7731.14-87 Polarographic determination of lead quantity.  

5. Packaging, storage and transportation, logo and quality certificate  

(1) The product is packed in iron drums, and the net weight of each barrel is 100kg. If the demand side has special requirements for packaging, it can be agreed upon by the supply and demand sides; (2) The products should be stored in the warehouse, and the car should be used when shipping, such as open storage or open car delivery, it must be covered with tarpaulin to prevent water leakage or mixing debris in the package; (3) The product package should be coated with obvious signs, the packaging should be accompanied by a finished product label, and the content of the mark and label should meet the requirements of GB/T3650-95; (4) At the same time of delivery, the supplier should issue a product quality certificate. Its content should comply with the provisions of GB/T3650-95.  

[Reprinted to retain the source – Yangtze River Nonferrous Network]  

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