CN-121976004-A - Heat treatment process method for inhibiting hydrogen embrittlement tendency of ultrahigh-strength elastic bearing piece

CN121976004ACN 121976004 ACN121976004 ACN 121976004ACN-121976004-A

Abstract

The invention relates to a heat treatment process method for inhibiting the hydrogen embrittlement tendency of an ultrahigh-strength elastic bearing part, which comprises the steps of carrying out pretreatment, cleaning and drying on a workpiece, spraying a hydrogen-free inorganic phosphate protective coating on stress concentration parts such as a spline, carrying out high-temperature quenching heating and long-time heat preservation under the protection of whole-course high-purity nitrogen, controlling the flow of the nitrogen in a segmented manner, carrying out oil quenching cooling, removing the coating, cleaning and drying again, and carrying out optimized low-temperature tempering at 200-240 ℃ under the protection of the nitrogen. According to the invention, through adopting a hydrogen-free protective atmosphere, setting a local hydrogen diffusion barrier, optimizing the uniformity of a quenching structure and adjusting tempering parameters to reduce dislocation density and internal stress and a multidimensional synergistic effect, the invasion and enrichment of hydrogen in the heat treatment process are obviously reduced, the hydrogen content of a workpiece is reduced by more than 80%, and the fracture toughness is obviously improved, so that the hydrogen embrittlement resistance of a component is improved by more than 30%, and the service safety and the service life of the component in a severe environment are effectively ensured.

Inventors

LIU GUOQIANG
PAN SHUMIN
YANG JUNFENG
CAO LI
XING YANMING
LI JUN
LV ZHONGHUI
ZHAO FU
WU HAO
WANG LEI

Assignees

内蒙古第一机械集团股份有限公司

Dates

Publication Date: 20260505
Application Date: 20260227

Claims (10)

1. A heat treatment process method for inhibiting the hydrogen embrittlement tendency of an ultrahigh-strength elastic bearing piece is characterized by comprising the following sequential steps: (1) Cleaning and drying the ultrahigh-strength elastic bearing piece; (2) Spraying a hydrogen-free inorganic phosphate coating on the stress concentration part of the elastic bearing piece to form an anti-oxidation decarburization isolation layer; (3) Quenching and heating and preserving heat, namely heating the elastic bearing piece to 910-930 ℃ in a quenching furnace with high-purity nitrogen as protective atmosphere in the whole process, and preserving heat for 170-190 min; (4) Quenching and cooling, namely rapidly transferring the elastic bearing piece after heat preservation into quenching oil for cooling; (5) Coating cleaning and recleaning, namely removing the anti-oxidation decarburization isolation layer, and recleaning and drying the elastic bearing piece; (6) Tempering treatment, namely tempering the elastic bearing piece for 140-180 min at 200-240 ℃ in a tempering furnace continuously fed with high-purity nitrogen, and then cooling to room temperature.
2. The method according to claim 1, wherein in the step (1), the water-based cleaning agent with the temperature of 40-60 ℃ is adopted for spraying, the spraying time is 10-15 min, and the drying is carried out at 120+/-10 ℃ for 15-25 min.
3. The method according to claim 1, wherein in the step (2), the particle size of the inorganic phosphate coating is 15-20 micrometers, the viscosity is 1500-2000 cP, and the thickness of the anti-oxidation decarburization isolation layer formed after spraying is 0.3-0.6 mm.
4. The method of claim 1, wherein in step (2), the stress concentration location comprises a spline location of the elastomeric bearing.
5. The method according to claim 1, wherein in the step (3), the purity of the high purity nitrogen gas introduced is not less than 99.99%, and the flow rate of the introduced is controlled in stages according to the furnace temperature: When the furnace temperature is lower than 400 ℃, the nitrogen flow is 2.0-2.5 m < 3 >/h; When the furnace temperature is 400-870 ℃, the nitrogen flow is adjusted to 3.5-4.0 m < 3 >/h; in the quenching heat preservation stage, the nitrogen flow is maintained at 2.5-3.0 m < 3 >/h.
6. The method according to claim 1, wherein in the step (4), the temperature of the quenching oil is 30-50 ℃, the transfer time of the elastic bearing piece from tapping to immersion of the quenching oil is 50-70 seconds, and the cooling time in the quenching oil is 35-55 minutes.
7. The method of claim 1, wherein in step (5), the anti-oxidation and decarbonization separation layer is removed by mechanical polishing, and polishing is performed by using 240-320 mesh sand paper.
8. The method according to claim 1, wherein in the step (6), the flow rate of the high-purity nitrogen gas introduced during tempering treatment is 2-3m 3/h.
9. The method according to claim 1, wherein in the step (6), after tempering and heat preservation are finished, the elastic force bearing piece is taken out for air cooling after the furnace temperature is reduced to below 100 ℃.
10. The method according to any one of claims 1-9, wherein the material of the ultra-high strength elastic load bearing member is ultra-high strength steel having a tensile strength of more than 1500 MPa.

Description

Heat treatment process method for inhibiting hydrogen embrittlement tendency of ultrahigh-strength elastic bearing piece Technical Field The invention belongs to the field of metal heat treatment, and particularly relates to a heat treatment process method for inhibiting the hydrogen embrittlement tendency of an ultrahigh-strength elastic force bearing part. Background The ultra-high strength elastic bearing piece is an elastic key piece of a suspension system of a special vehicle, and because the elastic key piece works in complex and severe service environments such as multiple frequencies, large impact vibration and the like, in the manufacturing process, the material is selected from high-strength tensile steel to meet the requirements of manufacturing and service performances. With the increasing demand for high load-bearing capacity of special vehicles, ultra-high strength steel is generally selected for manufacturing high-performance elastic load-bearing members. However, under the conditions of high stress and complex fatigue load, as the tensile strength of the ultra-high strength steel increases, the hydrogen embrittlement sensitivity of the material increases sharply, and the hydrogen embrittlement phenomenon of the elastic bearing piece is very easy to occur. The occurrence of the hydrogen embrittlement phenomenon can cause the remarkable reduction of mechanical property indexes (such as strength indexes, ductility indexes and fatigue indexes) of the ultra-high strength steel, and simultaneously cause the change of a fracture mechanism of the ultra-high strength steel, remarkably reduce the fatigue life of the ultra-high strength elastic bearing piece, and extremely easily cause the early failure of the elastic bearing piece to form potential safety hazards. Currently, the main heat treatment process of such components is quenching and low temperature tempering under a controlled atmosphere (usually a nitrogen-based atmosphere, i.e. a mixture of nitrogen and methanol). There is the disadvantage that 1) methanol is used as carrier gas, which is directly cleaved to 65.4% H 2、33% CO、0.7%CH4、0.1%CO2 at high temperature to form a large amount of diffusible hydrogen element. The comparison of the original state and the quenched state of the ultra-high strength elastic bearing piece shows that the hydrogen content of the ultra-high strength elastic bearing piece is increased by 0.45ppm in the quenching process, which also shows that the surface and the subsurface of the ultra-high strength elastic bearing piece are enriched with a large amount of diffusible hydrogen elements in the heating and heat preservation stage, and a large amount of diffusible hydrogen elements can not escape quickly in the subsequent cooling process, so that the invasion phenomenon of hydrogen is generated on the surface and the subsurface of the ultra-high strength elastic bearing piece, the increase of the hydrogen content of the ultra-high strength elastic bearing piece is caused, and the hydrogen embrittlement tendency of the ultra-high strength elastic bearing piece is obviously improved. 2) In the low-temperature tempering stage of heat treatment, the low-temperature tempering temperature of the ultra-high strength elastic bearing piece is 180+/-10 ℃, tempering is carried out in the temperature range, dislocation density is rapidly proliferated, and meanwhile, the internal stress is rapidly increased, so that the ultra-high strength elastic bearing piece has the characteristics of high strength, high hardness, high stress and the like. The existence of the typical characteristics and the existence of a large amount of diffusible hydrogen elements in the superposition environment can provide favorable conditions for hydrogen embrittlement fracture, remarkably increase the tendency of hydrogen embrittlement, and easily generate the phenomenon of hydrogen embrittlement, thereby causing early failure of the ultra-high strength elastic bearing piece. The prior art has obvious defects in effectively controlling the invasion of hydrogen and internal hydrogen traps in the heat treatment process. Disclosure of Invention The invention aims to overcome the defects of the prior art, and provides a heat treatment process method capable of remarkably reducing the hydrogen embrittlement tendency of an ultrahigh-strength elastic force bearing piece, which solves the problems that the existing ultrahigh-strength elastic force bearing piece has large hydrogen embrittlement tendency and low fatigue life, and is difficult to meet the requirements of high performance, long service life and high reliability of the elastic force bearing piece. In order to solve the technical problems, the invention provides a heat treatment process method for inhibiting the hydrogen embrittlement tendency of an ultrahigh-strength elastic bearing piece, which is characterized by comprising the following sequential steps: (1) Cleaning and drying the ultrahigh-str