CN104694709A - Heat treatment technique for improving hardness of 05Cr17Ni4Cu4Nb steel part - Google Patents

Abstract

The invention provides a heat treatment technique for improving hardness of a 05Cr17Ni4Cu4Nb steel part. The hardness of the 05Cr17Ni4Cu4Nb steel part can reach at least HRC48. The heat treatment technique comprises the following specific methods: salt bath heating, water-cooling quenching and solid dissolution, cold cryogenic treatment, machining molding and ageing. According to the method, ferrite and bainite in a steel structure can be transformed into austenite as much as possible by prolonging the solid solution and heat preservation time; the cold cryogenic treatment process is added; and the retained austenite is transformed into martensite as far as possible to obtain relatively high hardness while ageing, so that the problem that the Rockwell hardness of the 05Cr17Ni4Cu4Nb steel cannot easily reach the technical requirements of HRC48-52 according to the specification of the prior art is solved.

Description

A kind of heat-treatment technology method improving 05Cr17Ni4Cu4Nb steel components hardness

Technical field

The invention belongs to technical field of heat treatment technology, particularly the heat-treatment technology method of the high strength part of 05Cr17Ni4Cu4Nb steel making.

Background technology

05Cr17Ni4Cu4Nb steel belongs to PH Stainless Steel, according to the mechanical property of GB/T1220-2007 stainless steel bar table 10 PH Stainless Steel rod and the specification heat treating regime of Table A 5 PH Stainless Steel rod, 05Cr17Ni4Cu4Nb steel is through (1020-1060) DEG C rapid cooling solid solution, again through 480 DEG C of (470 DEG C-490 DEG C) timeliness, its hardness can reach Brinell hardness HBW >=375, Rockwell hardness HRC >=40, and some data is introduced, this material solid solution+480 DEG C of timeliness extreme hardness values can reach about HRC45.If come round, Overheating Treatment makes its hardness bring up to Rockwell hardness HRC >=48, passes through our repeatedly technological test, adopts the heat-treatment technology method of existing specification to be difficult to realize.

Applicant unit type product part gear used, Design Requirement Drawing: material 05Cr17Ni4Cu4Nb, heat treatment requirements HRC48-52.The heat-treatment technology method of our code requirement is: timeliness after the solid solution of bar blank, machine add-on type.By repeatedly technological test, continuous adjusting process parameter, experimental result gear part Rockwell hardness only has HRC42-45, does not reach the Rockwell hardness HRC48-52 of Design Requirement Drawing, cause the process for processing of this gear part to occur the problem that gets stuck, directly affect the quality of production of this type product.

Summary of the invention

In order to improve the heat treatment process quality of 05Cr17Ni4Cu4Nb steel gear, solve this gear part when processing according to the specification heat-treatment technology method that this area is general, hardness does not reach the problem of Design Requirement Drawing, applicant breaks through and obtains orthodox practice to 05Cr17Ni4Cu4Nb steel heat treatment in the art, propose a kind of new heat treating method, after solid solution, add ice-cold process, extend the solution heat time simultaneously.Adopt the gear that this new heat-treatment technology method is processed, its hardness can bring up to Rockwell hardness HRC48-49, meets product drawing, process specifications, solves this critical technological point.

Concrete technical scheme is:

Described a kind of heat-treatment technology method improving 05Cr17Ni4Cu4Nb steel components hardness, is characterized in that: described 05Cr17Ni4Cu4Nb steel components hardness at least reaches HRC48; Method comprises the following steps:

Step 1: to the preheating of 05Cr17Ni4Cu4Nb bar blank, Heating temperature is 800 DEG C-850 DEG C;

Step 2: to the solution hardening of 05Cr17Ni4Cu4Nb bar blank, Heating temperature is 1030 DEG C-1060 DEG C, soaking time is within 3 minutes, add that bar effective diameter is multiplied by 1.8 ~ 2.0 minutes/millimeter;

Step 3: to the ice-cold process of 05Cr17Ni4Cu4Nb bar blank, temperature is-60 DEG C ~-70 DEG C, and soaking time is 60-75 minute;

Step 4: to ageing treatment after 05Cr17Ni4Cu4Nb bar machine add-on type.

Beneficial effect

In the art, acknowledged technical specifications has been had for the stainless heat treating method of 05Cr17Ni4Cu4Nb, but applicant finds that the Rockwell hardness being difficult to realize 05Cr17Ni4Cu4Nb steel according to this technical specifications reaches the technical requirements of HRC48-52, for this applicant proposed with the heat-treatment processing process method of new salt bath heating, cold quenching solid solution+shaping rear timeliness of ice-cold sub-zero treatment+mechanical workout, add ice-cold process, and extend the solution heat time.Adopt the 05Cr17Ni4Cu4Nb steel gear that this new heat-treatment technology method is processed, its hardness can bring up to Rockwell hardness HRC48-49, meets product drawing, process specifications.

Accompanying drawing explanation

Fig. 1: cross-sectional metallographic tissue, wherein a, 100X; B, 500X; C, 500X; D, 500X.

Fig. 2: vertical section metallographic structure, 100X.

Fig. 3: grain fineness number, 400X.

Fig. 4: transmission electron microscope tissue, wherein a, 200K, tiny precipitation; B, 15K, low power pattern; C, 27.5K, austenite; D, austenite electron diffraction; E, 20K, austenite; F, 20K, austenite; G, 88K, NbC; H, NbC, electron diffraction.

Embodiment

Below in conjunction with specific embodiment, the present invention is described:

To process certain product parts gear in the present embodiment, Design Requirement Drawing: material 05Cr17Ni4Cu4Nb, supply of material state: hot rolling, specification: Φ 20X400, heat treatment requirements HRC48-52.Because code requirement heat treating method carries out repeatedly technological test, continuous adjusting process parameter, experimental result gear part Rockwell hardness only has HRC42-45, do not reach the Rockwell hardness HRC48-52 of Design Requirement Drawing, therefore to adopting, existing specification heat-treatment technology method carries out solid solution, the metallographic structure of timeliness part is analyzed:

In Fig. 1, cross-sectional metallographic tissue shows tempered martensite+a small amount of bainite+granular δ-ferrite, and in Fig. 2, vertical section metallographic structure shows the δ-ferrite of tempered martensite+a small amount of bainite+prolong rolling direction; Showing grain size number in Fig. 3 is 10 grades.Can find out tissue to there is a small amount of bainite and ferrite from metallographic structure photo, these tissues can affect the final ageing strengthening hardness of material.In order to reduce or eliminate these tissues, can solve by extending the solution heat time.

Can find out in the transmission electron microscope tissue of Fig. 4, the tiny precipitation of Fig. 4-a is the strengthening phase of second-phase, and Fig. 4-b is martensite lath pattern, does not observe the precipitation of obvious cementite, have partial austenitic to exist between Fig. 4-c martensite lath, its diffractogram is shown in figure Fig. 4-d; In Fig. 4-e and Fig. 4-f, austenite is tiny bulk morphologies; In Fig. 4-g, martensitic matrix can be observed NbC particle.By transmission electron microscope fabric analysis, can observe in tissue and there is austenite.And austenitic existence will affect the ageing strengthening hardness of material to a great extent.Taking sub-zero treatment, make austenite all change into martensite, improving the ageing strengthening hardness of material by increasing martensite volume.

By above-mentioned analysis, adopt existing specification heat-treatment technology method, still there is more bainite, ferrite and austenite in material solid solution structure, they will affect ageing strengthening hardness after material solid solution to a certain extent.Therefore, we, in new process design, add ice-cold process, and extend the solution heat time.Through repeatedly technological test, determine the heat-treatment processing process method of salt bath heating, cold quenching solid solution+shaping rear timeliness of ice-cold sub-zero treatment+mechanical workout.Adopt the gear that this new heat-treatment technology method is processed, its hardness can bring up to Rockwell hardness HRC48-49, meets product drawing, process specifications, solves this critical technological point.

Processing step concrete in the present embodiment is:

Step 1: to the preheating of 05Cr17Ni4Cu4Nb bar blank, heating installation is middle thermohaline liquid furnace, and Heating temperature is 800 DEG C-850 DEG C; Till warm up time is diathermanous with bar blank;

Step 2: to the solution hardening of 05Cr17Ni4Cu4Nb bar blank, heating installation is High Temperature Salt Bath Furnace, and Heating temperature is 1030 DEG C-1060 DEG C, soaking time is within 3 minutes, add that bar effective diameter is multiplied by 1.8 ~ 2.0 minutes/millimeter; Refrigerant adopts the tap water of water temperature≤40 DEG C, and method of cooling is cooled to coolant temperature for being immersed in refrigerant by bar blank;

Step 3: to the ice-cold process of 05Cr17Ni4Cu4Nb bar blank, equipment is refrigerated tank, and temperature is-60 DEG C ~-70 DEG C, and soaking time is 60-75 minute, and then outlet air cooling is to room temperature;

Step 4: to ageing treatment after 05Cr17Ni4Cu4Nb bar machine add-on type, heating installation is vacuum oven, and Heating temperature is 480 DEG C-490 DEG C, and soaking time is 4 hours, method of cooling for be chilled to room temperature with stove, vacuum oven vacuum tightness≤6X10 ^-2pa.

The key of above-mentioned processing step is step 2 and step 3, in step 2, soaking time is within 3 minutes, add that bar effective diameter is multiplied by 1.8 ~ 2.0 minutes/millimeter, longer than the soaking time of code requirement, make that the ferrite in structure of steel and bainite are as far as possible many is transformed into austenite, to form the martensite of more during ice-cold sub-zero treatment; And step 3 adopts ice-cold sub-zero treatment, make residual austenite change martensite into as far as possible, during to ensure timeliness, obtain higher hardness.

Claims (1)

1. improve a heat-treatment technology method for 05Cr17Ni4Cu4Nb steel components hardness, it is characterized in that: described 05Cr17Ni4Cu4Nb steel components hardness at least reaches HRC48; Method comprises the following steps:

Step 1: to the preheating of 05Cr17Ni4Cu4Nb bar blank, Heating temperature is 800 DEG C-850 DEG C;

Step 2: to the solution hardening of 05Cr17Ni4Cu4Nb bar blank, Heating temperature is 1030 DEG C-1060 DEG C, soaking time is within 3 minutes, add that bar effective diameter is multiplied by 1.8 ~ 2.0 minutes/millimeter;

Step 3: to the ice-cold process of 05Cr17Ni4Cu4Nb bar blank, temperature is-60 DEG C ~-70 DEG C, and soaking time is 60-75 minute;

Step 4: to ageing treatment after 05Cr17Ni4Cu4Nb bar machine add-on type.