Heat treatment method for H13 steel hard surface overlaying layer
Technical Field
The invention relates to the field of die machining and heat treatment, in particular to a heat treatment method for a H13 hot-work die steel hard-face overlaying layer.
Background
The H13 hot work die steel has the advantages of low cost, high strength, good ductility, good wear resistance, good impact toughness and the like, and is widely applied as a die manufacturing material. The die bears complex load in the service process, and the surface of the die is required to have higher hardness, wear resistance and the like. However, after the die is in service for a period of time, the surface of the die is seriously damaged by abrasion, cracks and the like, and the personal safety of production and staff is directly threatened. The new mold must be replaced immediately, which results in increased production costs and wasted resources for the enterprise. The service life of the die can be obviously prolonged and the service performance of the die can be increased by the repair or surface strengthening technology. At present, submerged arc welding technology has been the most widely used method. The technology has the advantages of simple equipment, low production cost, high deposition rate and good appearance of the welding layer. Unfortunately, some welding defects in the weld area, such as dislocations, residual welding stress, non-uniform texture components, etc., may adversely affect the mechanical properties of the weld overlay.
Therefore, in order to reduce or even eliminate the adverse effect of the defects such as dislocation, welding residual stress, structural component unevenness and the like on the service performance of the weld overlay, a heat treatment method of the H13 steel hardfacing weld overlay is proposed.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a heat treatment method of an H13 steel hard-surface overlaying layer, which reduces or even eliminates welding defects and improves the structure and the service performance of the hard-surface overlaying layer.
The technical purpose of the invention is realized by the following technical scheme.
A heat treatment method for an H13 steel hardfacing overlaying layer comprises the following steps:
step 1, carrying out surfacing by taking H13 steel as a welding matrix to obtain a hard-surface surfacing layer
In step 1, surfacing process parameters: the preheating temperature is 250-300 ℃, the interlayer temperature is 200-250 ℃, the diameter of a welding wire is 1-1.2 mm, the welding current is 100-140A, the arc voltage is 17-25V, the welding speed is 5-10 mm/s, the polarity of a power supply is direct current reverse connection, and the chemical components of the hard surfacing layer are calculated according to the weight percentage: 0.03 to 0.07% of C, 0.40 to 0.60% of Si, 1.00 to 1.35% of Mn, 9.50 to 13.50% of Cr, 0.30 to 0.65% of Mo, 0.06 to 0.15% of V, 1.15 to 1.80% of Ni, and the balance of Fe.
When the hardfacing surfacing layer is built up in the step 1, the technical scheme of the mandrel surfacing repair method and the mandrel surfacing layer structure in the prior invention application (application number 2017105568306, application date 2017, 7 and 10) is adopted, and surfacing is carried out on the surface of H13 steel to form a wear-resistant layer on the outer surface of the H13 steel to serve as the hardfacing surfacing layer.
And 2, working the hard surface overlaying layer prepared in the step 1 to reach the size required by the mold, then tempering in the air atmosphere, heating from the room temperature of 20-25 ℃ to the tempering temperature of 250-650 ℃ at the heating speed of 5-20 ℃/min, tempering and heat preservation for 0.5-6 h, taking out, and air cooling to the room temperature of 20-25 ℃.
In the step 2, the temperature is raised from the room temperature of 20-25 ℃ to the tempering temperature at the temperature raising speed of 5-10 ℃/min, the tempering temperature is 350-450 ℃, and the tempering heat preservation time is 1-2 h.
In the technical scheme, the H13 steel is cut by a wire cutting machine to serve as a welding matrix, before surfacing, an H13 steel sample is mechanically polished by abrasive paper, then ultrasonically cleaned in a sodium hydroxide aqueous solution to remove grease on the surface of the sample, finally washed by deionized water, ultrasonically vibrated by absolute ethyl alcohol, and dried for later use.
The heat treatment method of the H13 steel hardfacing overlaying layer is applied to improving the hardness of the overlaying layer and reducing the abrasion weight loss of the overlaying layer.
Compared with the prior art, the invention has the advantages and beneficial effects that: the invention adopts the postweld tempering heat treatment to eliminate the welding defects in the H13 steel surface hard surface overlaying layer, such as dislocation, welding residual stress, uneven tissue components and the like. The structure and the mechanical property of the surfacing layer are improved by reasonably controlling the tempering temperature, the heat preservation time and the heating rate.
Drawings
FIG. 1 illustrates the weld pattern of the hardfacing weld overlay.
FIG. 2 shows the structure of the hardfacing layer after 2h of tempering at 350 ℃ in the invention.
FIG. 3 shows the structure of the hardfacing layer after tempering for 1 hour at 450 ℃ in the invention.
FIG. 4 shows the structure of the hardfacing layer after tempering for 2 hours at 450 ℃ in the invention.
Detailed Description
To further illustrate the features and advantages of the present invention, the following description is given in conjunction with the examples, but the present invention is not limited to the examples. And observing the structure of the surfacing layer by adopting a scanning transmission electron microscope. And testing the hardness and the abrasion weight loss of the overlaying layer by adopting a Vickers microhardness tester and a friction abrasion testing machine. When the hardfacing surfacing layer is built up, the technical scheme in the prior invention application of the mandrel surfacing repair method and the mandrel surfacing layer structure (application number 2017105568306, application date 2017, 7 and 10) is adopted to build up the H13 steel surface to form a wear-resistant layer on the outer surface of the H13 steel as the hardfacing surfacing layer.
Example 1
(1) H13 steel was cut out as a weld matrix with a wire cutter. Before surfacing, a sample is mechanically polished by 400-mesh, 600-mesh, 800-mesh and 1000-mesh sand papers, is placed into absolute ethyl alcohol after being washed by tap water to remove particles attached to the surface through ultrasonic oscillation, is ultrasonically washed in sodium hydroxide after being dried to remove grease on the surface of the sample, is washed by distilled water, and is ultrasonically oscillated and dried by the absolute ethyl alcohol for later use.
(2) Surfacing: the preheating temperature is 250-300 ℃, the interlayer temperature is 200-250 ℃, the diameter of a welding wire is 1.2mm, the welding current is 100-140A, the arc voltage is 17-25V, the welding speed is 5mm/s, and the polarity of a power supply is direct current reverse connection. Chemical components of the hard surface overlaying layer: 0.03 to 0.07% of C, 0.40 to 0.60% of Si, 1.00 to 1.35% of Mn, 9.50 to 13.50% of Cr, 0.30 to 0.65% of Mo, 0.06 to 0.15% of V, and 1.15 to 1.80% of Ni. The hardness and the abrasion weight loss of a welding state overlaying layer after overlaying are 356.0 +/-8.0 HV0.2And 18.6. + -. 0.2 mg.
(3) Processing: and performing finish machining on the prepared hard-surface overlaying layer according to the drawing requirements so as to reach the size required by the die.
(4) And (3) heat treatment: and tempering the processed die, and air-cooling to room temperature to obtain a finished product. The tempering temperature is 350 ℃, the heat preservation time is 2h, and the heating rate is 10 ℃/min.
(5) The transmission electron microscope observation of the hard-surface overlaying layer obtained by adopting the steps shows that the structure of the overlaying layer is refined, the welding defects are reduced, and the secondary hardening effect is obvious. The hardness of the overlaying layer is 386.8 +/-7.6 HV0.2. The mass loss of the weld overlay after the fretting wear test was 11.4 + -0.8 mg.
Example 2
(1) The same as in example 1.
(2) The same as in example 1.
(3) The same as in example 1.
(4) And (3) heat treatment: and tempering the processed die, and air-cooling to room temperature to obtain a finished product. The tempering temperature is 450 ℃, the heat preservation time is 1h, and the heating rate is 10 ℃/min.
(5) The transmission electron microscope observation of the hard-surface overlaying layer obtained by adopting the steps shows that the structure of the overlaying layer is refined, the welding defects are reduced, and no secondary hardening is generated. The hardness of the overlaying layer is 330.8 +/-6.4 HV0.2. The mass loss of the weld overlay after the fretting wear test was 14.9 + -0.2 mg.
Example 3
(1) The same as in example 1.
(2) The same as in example 1.
(3) The same as in example 1.
(4) And (3) heat treatment: and tempering the processed die, and air-cooling to room temperature to obtain a finished product. The tempering temperature is 450 ℃, the heat preservation time is 2h, and the heating rate is 10 ℃/min.
(5) The transmission electron microscope observation of the hard-surface overlaying layer obtained by adopting the steps shows that the structure of the overlaying layer is refined, the welding defects are reduced, and the secondary hardening effect is obvious. The hardness of the overlaying layer is 370.0 +/-6.3 HV0.2. The mass loss of the weld overlay after the fretting wear test was 11.8 + -1.3 mg.
The heat treatment of the H13 steel hard surface overlaying layer can be realized by adjusting the technological parameters according to the content of the invention, and tests show that the hardness of the overlaying layer is improved and the abrasion weight loss of the overlaying layer is reduced. The invention has been described in an illustrative manner, and it is to be understood that any simple variations, modifications or other equivalent changes which can be made by one skilled in the art without departing from the spirit of the invention fall within the scope of the invention.