JP5123014B2 - High temperature wear resistant material - Google Patents

Description

  The present invention relates to a high-temperature wear-resistant material used for a protective liner for a blast furnace member, an inner liner of a bucket that receives high-temperature red hot coke discharged from a coke oven and transports it to a coke dry fire extinguishing facility.

  Usually, as various members used for distributing the charge such as iron ore, lime, coke and the like to the center of the blast furnace, a swivel chute, a movable armor, an ore receiving metal, and the like are used. These blast furnace members have a liner embedded in the surface layer portion thereof, and are protected from impact caused by dropping of the charged material and wear caused by sliding after contact. As the liner for the blast furnace member, high-chromium steel or high-temperature wear-resistant material made of a cast-up material of high-chromium steel and carbide (WC) particles is used (see Patent Documents 1 and 2).

Japanese Utility Model Publication No. 7-33964 JP 11-131114 A

  Moreover, the bucket which receives the high-temperature red hot coke discharged | emitted from the coke oven and conveys it to a coke dry-type fire extinguishing equipment is provided with the liner in the inner surface. This liner protects the inner surface of the bucket from impact caused by the fall of red hot coke and wear due to sliding after contact. As this liner, Mn-Cr austenitic steel with high manganese content, which requires high temperature wear resistance, for example, 0.3C-12Mn-16Cr-4Ni-0.3N-Fe bal. A high temperature wear resistant material consisting of

  The wear resistance of this Mn—Cr austenitic steel is due to work hardening that appears upon receiving external forces such as impact force and crushing force applied to the surface. Therefore, for example, when exposed to high temperature and wear conditions due to impact caused by dropping of red hot coke or sliding after contact, a work hardened layer is formed on the surface, and excellent wear resistance is exhibited. As a result, constant wear resistance is always maintained while balancing the progress of wear and the formation of a hardened layer. Due to the continued friction resistance, Mn—Cr austenitic steel is often used as a high temperature wear resistant material.

  By the way, the high chromium steel and the Mn—Cr austenitic steel described above usually contain several percent of Ni in order to improve the high temperature strength. However, in recent years, the demand for Ni has increased, and the price of Ni has soared, so the raw material costs of high chromium steel and Mn—Cr austenitic steel produced as high temperature wear resistant materials have increased. As a result, there is a problem that the manufacturing cost increases.

  Accordingly, an object of the present invention is to obtain an inexpensive high temperature wear resistant material having excellent wear resistance in a high temperature environment.

  In order to solve the above-described problems, the high temperature wear resistant material of the present invention includes C: 0.2 to 0.5 wt%, Si: 0.2 to 1.5 wt%, Mn: 16 to 24 wt%, Cr: 12 to 12. It contains 20 wt%, N: 0.1 to 0.5 wt%, and the balance consists of Fe and inevitable impurities.

  That is, by producing a high-temperature wear-resistant material with Mn-Cr austenitic steel that does not contain Ni and increases the content of inexpensive Mn instead of Ni, In addition to ensuring mechanical properties and wear resistance, manufacturing costs were reduced.

The reason why the content of each alloy element is limited to the above range will be described.
C is an element effective for improving high-temperature strength and wear resistance, and is contained in an amount of 0.2 wt% or more in order to ensure strength and wear resistance. On the other hand, since the toughness decreases as the content increases, the upper limit is set to 0.5 wt% so that cracking due to insufficient toughness does not occur.

  Si acts as a deoxidizer during the melting of steel, improves the flow of hot water, improves castability, and improves heat resistance. Therefore, Si is contained in an amount of 0.2 wt% or more. On the other hand, if the content increases, the toughness decreases and the possibility of cracking increases, so the upper limit is made 1.5 wt%.

  Mn is an element that has a deoxidizing action and detoxifies by fixing S, stabilizes the austenite phase and improves strength and work hardenability, but contains Ni as compared with conventional steel. In order to maintain the stability of the austenite phase, it is necessary to contain 16 wt% or more. On the other hand, if excessively contained, the price increases, so the upper limit is made 24 wt%.

  Cr needs to be contained in an amount of 12 wt% or more in order to stabilize austenite by a synergistic effect with Mn and to improve oxidation resistance and heat resistance. On the other hand, if it is contained excessively, the toughness decreases, so the upper limit is made 20 wt%.

  N is required to be contained in an amount of 0.1 wt% or more in order to stabilize the austenite phase and improve the strength. However, if excessively contained, N deteriorates toughness and decreases hot workability, so the upper limit is set. 0.5 wt%.

  The high-temperature friction-resistant material of the present invention does not contain Ni and is manufactured from Mn—Cr austenitic steel having a higher Mn content than conventional steel, thereby ensuring high-temperature wear resistance and ensuring the conventional Mn content. -It can be manufactured at a lower cost than when Cr-based austenitic steel is used.

  Embodiments of the present invention will be described below. Table 1 shows the composition of the Mn—Cr austenitic steel (Example) of the embodiment and the conventional Mn—Cr austenitic steel (Comparative Example) described above. C and S were analyzed by an infrared absorption method, N was analyzed by an inert gas melting thermal conductivity method, and other elements were analyzed by an induction plasma emission spectroscopic analysis method.

Various tests for confirming the performance were performed on the materials of the experimental example and the comparative example.
For various tests, first, an as-cast product obtained by pouring molten metal having the composition shown in Table 1 into a sand mold for a 30 tY block was heat-treated under the following conditions, and cut into the required size for testing. Created a piece.
(Heat treatment conditions)
Heating temperature: 1100 ° C
Heating rate: 100 ° C./hour Holding time: 5.5 hours Cooling method: water cooling

  Next, in order to confirm the toughness against impacts at normal temperature and high temperature environment, impact tests were performed at normal temperature, 500 ° C. and 700 ° C. The impact test was performed using the Charpy impact test method specified in JIS Z2242, and the Charpy impact value was obtained from the V-notch test piece specified in JIS Z2202. The test results are shown in Table 2.

  In the test results shown in Table 2, it was confirmed that the toughness was superior to the comparative example because the V-notch Charpy impact value of the example was larger than that of the comparative example at each temperature.

  Moreover, in order to confirm the mechanical strength in normal temperature and a high temperature environment, the tension test was implemented in normal temperature, 500 degreeC, and 700 degreeC. The tensile test is carried out using the tensile test method specified in JIS Z2241 at normal temperature and in JIS G0567 at high temperature. No. II type test piece), tensile strength, yield strength, elongation and drawing were determined. The test results are shown in Table 3.

  From the test results shown in Table 3, it was confirmed that at each temperature, the mechanical strength (tensile strength and proof stress) of the example was equal to or greater than that of the comparative example, and the elongation and drawing were the same.

  Furthermore, in order to confirm the surface hardness in a normal temperature and high temperature environment, a hardness test was performed at normal temperature, 500 ° C. and 700 ° C. In this hardness test, Vickers hardness was determined by a method according to JIS Z2244 at normal temperature and JIS Z2252 at high temperature. The test results are shown in Table 4.

  From the test results shown in Table 4, it was confirmed that at each temperature, the example had the same hardness as the comparative example. Here, since it is estimated that it has equivalent abrasion resistance when it has equivalent hardness, it can be estimated that an Example has the abrasion resistance equivalent to a comparative example.

  As described above, it was confirmed that the examples had impact resistance, mechanical strength, and hardness equivalent to those of the comparative examples. Therefore, the high-temperature wear-resistant material according to the present invention can be manufactured at low cost by not containing expensive Ni, and can ensure high-temperature wear resistance equivalent to that of conventional high-temperature wear-resistant materials containing Ni. it can.

Claims (1)

C: 0.2 to 0.5 wt%, Si: 0.2 to 1.5 wt%, Mn: 16 to 24 wt%, Cr: 12 to 20 wt%, N: 0.1 to 0.5 wt%, balance Ri Do Fe and unavoidable impurities, hot wear resistant material used in the inner liner of the bucket carrying protective liner of the blast furnace member or kiln out the red-hot coke from the coke oven, until receiving the coke dry digestion facilities.