阅读说明：本技术 一种蠕墨铸铁铁水的预处理剂及预处理方法 (Pretreatment agent and pretreatment method for vermicular graphite cast iron molten iron ) 是由 曹月山 杨涛 侯广怀 王树宝 于 2019-10-15 设计创作，主要内容包括：本发明涉及蠕墨铸铁技术领域,具体涉及一种蠕墨铸铁铁水的预处理剂及预处理方法,所述预处理剂包括以下组分：镧、铈、镨、钕、钪和铁；所述方法为在镁包芯线加入铁水之前的3分钟内将上述预处理剂加入处理包中。采用本预处理剂进行预处理,铁水后期不易衰退,获得的铸件金相组织和机械性能优良；本预处理方法操作简单方便、适用性强,可广泛用于各类铸件生产过程中,对于蠕铁缸体、缸盖类铸件尤其适用。(The invention relates to the technical field of vermicular cast iron, in particular to a pretreating agent and a pretreating method for vermicular cast iron molten iron, wherein the pretreating agent comprises the following components: lanthanum, cerium, praseodymium, neodymium, scandium, and iron; the method is characterized in that the pretreating agent is added into a treatment bag within 3 minutes before the magnesium cored wire is added into molten iron. The pretreatment agent is adopted for pretreatment, so that molten iron is not easy to fade in the later period, and the obtained casting has excellent metallographic structure and mechanical property; the pretreatment method is simple and convenient to operate, has strong applicability, can be widely used in the production process of various castings, and is particularly suitable for vermicular iron cylinder body castings and cylinder cover castings.)

1. The pretreatment agent for the vermicular cast iron molten iron is characterized by comprising the following components: lanthanum, cerium, praseodymium, neodymium, scandium, and iron.

2. The pretreatment agent for vermicular cast iron molten iron according to claim 1, wherein the pretreatment agent comprises the following components in percentage by weight:

25-40% of lanthanum, 60-70% of cerium, 0-2% of praseodymium, 0-1% of neodymium, 0-2% of scandium and the balance of iron.

3. The pretreatment agent for vermicular cast iron molten iron according to claim 2, wherein the pretreatment agent comprises the following components in percentage by weight:

27-37% of lanthanum, 60-66% of cerium, 0-1% of praseodymium, 0-0.5% of neodymium, 0-1% of scandium and the balance of iron.

4. The method for pretreating the molten iron of the vermicular cast iron is characterized in that a pretreating agent is added into a treatment bag within 3 minutes before magnesium cored wires are added into the molten iron.

5. The method for pretreating vermicular cast iron liquid iron according to claim 4, wherein the adding amount of the pretreating agent is determined according to the content of trace interfering elements in the base iron liquid.

6. the method for pretreating vermicular cast iron liquid iron according to claim 5, wherein the trace interfering elements comprise titanium, arsenic, sulfur, antimony, oxygen, lead and aluminum.

7. The method for pretreating vermicular cast iron liquid iron according to claim 5, wherein the addition amount (kg/t) of the pretreatment agent per ton of liquid iron is KxThe content of trace interfering elements in the original liquid iron is 100, K is a variable factor, and K is 2.5-45.5.

8. The method for pretreating vermicular cast iron liquid iron according to claim 7, wherein when the total content of trace interfering elements in the base iron liquid is less than or equal to 0.05%, K is 2.5-25.5,

when the total content of the trace interference elements in the original molten iron is more than 0.05% and less than or equal to 0.1%, K is 25.6-45.5.

Technical Field

The invention relates to the technical field of vermicular cast iron, in particular to a pretreating agent and a pretreating method for vermicular cast iron molten iron.

Background

The casting industry is the basic industry of the national manufacturing industry, and castings are widely applied to the equipment manufacturing industry and are core components of the equipment manufacturing industry. With the continuous development of the industries, the quality requirement of castings is higher and higher. This is especially true of engine castings, and as environmental requirements increase, so does the demand for castings.

At present, the creep treatment of molten iron is generally carried out by adopting a flushing method and a wire feeding method, and the wire feeding method has many advantages compared with the flushing method; secondly, the molten iron cooling is less, and degree of automation is high, and the operating environment is good. Due to the difference of production conditions, such as furnace charge source and quality, production equipment and process flow, vermicular cast iron vermicular treatment processes of various manufacturers are different, but the problems that molten iron can be used for a short time after vermicular cast, the molten iron is degraded in the later period, and the metallographic structure cannot meet the requirements generally exist. In order to ensure that molten iron does not decline in the later stage, the method for increasing the adding amount of the magnesium cored wire is usually adopted to prolong the service life of the molten iron in the present stage, but the method cannot fundamentally solve the problems, but can cause the spheroidization rate of the molten iron to be high, the finally obtained casting has a large shrinkage porosity tendency, and the metallographic structure still cannot meet the standard requirements.

Disclosure of Invention

aiming at the problem that the metallographic structure cannot meet the standard requirement due to the decline of molten iron or high nodularity of the molten iron in the existing vermicular cast iron process, the invention provides a pretreating agent and a pretreating method for the molten iron of the vermicular cast iron, wherein the pretreating agent is used before a magnesium cored wire is added, the molten iron is not easy to decline in the later stage after pretreatment, and the obtained casting has excellent metallographic structure and mechanical property; the pretreatment method is simple and convenient to operate, has strong applicability, can be widely used in the production process of various castings, and is particularly suitable for vermicular iron cylinder body castings and cylinder cover castings.

in a first aspect, the invention provides a pretreatment agent for vermicular cast iron molten iron, which comprises the following components: lanthanum, cerium, praseodymium, neodymium, scandium, and iron.

further, the pretreatment agent comprises the following components in percentage by weight:

25-40% of lanthanum, 60-70% of cerium, 0-2% of praseodymium, 0-1% of neodymium, 0-2% of scandium and the balance of iron.

Further, the pretreatment agent comprises the following components in percentage by weight:

27-37% of lanthanum, 60-66% of cerium, 0-1% of praseodymium, 0-0.5% of neodymium, 0-1% of scandium and the balance of iron.

In a second aspect, the invention provides a method for pretreating vermicular cast iron liquid iron, which is to add the pretreating agent into a treatment bag within 3 minutes before magnesium cored wires are added into the liquid iron.

further, the addition amount of the pretreating agent is determined according to the content of trace interference elements in the base iron.

further, the trace interfering elements include titanium, arsenic, sulfur, antimony, oxygen, lead, and aluminum.

furthermore, the addition amount (kg/t) of the pretreatment agent for molten iron per ton is K multiplied by the content of trace interference elements in the original molten iron,% multiplied by 100, K is a variable factor, and K is 2.5-45.5.

Furthermore, when the total content of the trace interference elements in the original molten iron is less than or equal to 0.05 percent, K is 2.5 to 25.5,

When the total content of the trace interference elements in the original molten iron is more than 0.05% and less than or equal to 0.1%, K is 25.6-45.5.

The raw materials of the pretreating agent provided by the invention contain rare earth elements, the fading phenomenon is not obvious, the tendency of forming slag inclusion is reduced, the stability of rare earth sulfide and oxide is high, the granularity is fine, the compounds are difficult to float upwards in molten iron, and the mismatching degree of the compounds and graphite crystal lattices is small, so that the compounds can be used as heterogeneous cores of graphite precipitation, thereby having the function of inoculation;

The pretreatment method limits the adding amount of the pretreatment agent, the dosage of the rare earth elements in the molten iron is reasonable when the pretreatment method is used, and the problem of cast iron white cast iron inclination enhancement caused by excessive residual rare earth in the molten iron after the pretreatment method is used can be effectively avoided;

According to the pretreatment method, the magnesium cored wire is added after the pretreatment agent is independently added into the molten iron instead of integrating the components into the magnesium cored wire, so that the flexible adjustment of the addition amount can be realized according to the real-time fluctuation of furnace burden; the pretreatment method provided by the invention also limits the adding time of the pretreatment agent to be within 3 minutes before the magnesium cored wire is added, so that the boiling effect of the magnesium cored wire can be fully exerted, molten iron is more uniform after reaction, and the condition that the effective pretreatment effect cannot be achieved due to too early adding time can be effectively avoided.

the casting obtained by the pretreatment agent and the pretreatment method provided by the invention has excellent mechanical property and metallographic structure.

Drawings

In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present invention, the drawings used in the description of the embodiments or prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.

FIG. 1 is a photograph of a portion of a casting obtained in example 2;

FIG. 2 is a metallographic structure photograph of a casting obtained in example 2;

FIG. 3 is a metallographic structure photograph of a casting obtained in comparative example 1;

FIG. 4 is a metallographic structure photograph of a casting obtained in comparative example 2;

FIG. 5 is a metallographic structure photograph of a casting obtained in comparative example 3;

FIG. 6 is a metallographic structure photograph of a casting obtained in comparative example 4;

FIG. 7 is a metallographic structure photograph of a casting obtained in comparative example 5;

FIG. 8 is a partial photograph of a casting obtained in comparative example 6;

FIG. 9 is a metallographic structure photograph of a casting obtained in comparative example 6;

FIG. 10 is a partial photograph of a casting obtained in comparative example 7;

fig. 11 is a metallographic structure photograph of a casting obtained in comparative example 7.

Detailed Description

in order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention, and it is obvious that the described embodiment is only a part of the embodiment of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

the mechanical property detection is carried out according to GB/T part 1 of a metal material tensile test: room temperature test method.