CN104451705A

CN104451705A - Gear manufacturing process

Info

Publication number: CN104451705A
Application number: CN201410618984.XA
Authority: CN
Inventors: 钱文明
Original assignee: Wuxi Baishun Machinery Factory
Current assignee: Wuxi Baishun Machinery Factory
Priority date: 2014-11-06
Filing date: 2014-11-06
Publication date: 2015-03-25

Abstract

The invention provides a gear manufacturing process, comprising the steps of (1) preparing pure 20CrAl steel by adopting vacuum melting and vacuum consumable electroslag technology, wherein the 20CrAl steel comprises the following chemical components in percentage by weight: 0.17-0.22% of carbon, 1.1-1.2% of aluminum, 1.3-2.0% of chromium, less than 0.004% of phosphorus, less than 0.004% of sulfur, 4ppm of oxygen, less than 0.4ppm of hydrogen and the balance of iron; and (2) performing plastic hot processing on the raw material by conventional forging or rolling. The gear manufacturing process has the advantages of simple thermal treatment, low decarburization sensitivity, moderate annealing hardness, corrosion resistance and low material price.

Description

A kind of gear manufacturing technology

Technical field

The present invention relates to a kind of gear manufacturing technology, belong to machinery manufacturing technology field.

Background technology

As everyone knows, gear is the key foundation part in mechanical means, and it should have excellent contacting fatigue resistance, and the quality of gear quality is directly connected to the work-ing life of whole equipment.And the quality of gear quality depends on gear material and thermal treatment process thereof to a great extent.In its manufacturing process, conventional thermal treatment is quenching and low-temperaturetempering, thoroughly can not eliminate internal stress and residual austenite for low-temperaturetempering, and workpiece is preserved long-term or can deform in use procedure.For avoiding this situation to occur, comparatively complicated thermal treatment need be carried out.Chrome-free Pinion Steel is the multicomponent alloy Pinion Steel developed afterwards, and wherein often containing alloying elements such as silicon, manganese, molybdenum, vanadium, stainless steel adapts to the industrial developments such as chemistry, oil, shipbuilding and develops.The gear worked in various corrosive environment must have high corrosion resisting property, and the steel of general chrome content is not competent, has therefore developed high carbon and chromium stainless steel.Chromium is the main alloy element of this type of steel, as 9Cr18,9Cr18Mo etc.Its weak point is that range of application has limitation.Gear in the devices such as aircraft engine, aerospacecraft, internal combustion turbine works under high temperature and high speed and high-load condition, its working temperature is more than 300 DEG C, the maximum operating temperature of 42CrMo steel is no more than 180 DEG C, the working temperature of the low-alloy Pinion Steel of siliceous, molybdenum, vanadium, aluminium also can only below 250 DEG C, if temperature raises again, then hardness can be caused sharply to decline and lost efficacy.Therefore the gear worked at relatively high temperatures, should adopt and have sufficiently high hot hardness, high temperature abrasion resistance, high temperature contact fatigue strength and the high performance Pinion Steel such as anti-oxidant.Current high-temperature steel has two classes: rapid steel class (as W18Cr4V) and high chromium martensitic stainless steel (as Cr14Mo4V), and its weak point is that price comparison is high.These gears work under high contact stress, experience a shock continually and wear and tear, therefore to large gear except the requirement that should have general gear, also require that there are enough toughness and high ultimate compression strength and hardness in heart portion, so select the alloy carburizing steel of low-carbon (LC) to manufacture.After carburizing and quenching and low-temperaturetempering, top layer hard wear resistant, heart portion keeps high obdurability, and surface is in compressive stress state simultaneously, favourable for fatigue lifetime to raising.Conventional carbonized Gear Steel has 20Cr, 20CrMnTi, 35# steel, 45# steel, 40Cr, 42CrMo, 35CrMo etc., and their weak point is that price comparison is high.

Summary of the invention

The invention provides a kind of gear manufacturing technology, thermal treatment be simple, Decarburization Sensitivity is little, annealing hardness is moderate, the hard bainite gear manufacturing technology that corrosion-resistant, price is low.The present invention mainly adopts carburizing treatment method and special heat treating method the Gear Processing with certain chemical composition to be become the High-performance gear that top layer is hard bainite structure, heart portion is low-carbon (LC) tempered martensite.

For solving above technical problem, the invention provides following technical scheme: a kind of gear manufacturing technology, (1) the pure 20CrAl steel adopting vacuum metling and vacuum consumable electroslag technology to prepare, the weight percent of its chemical composition is: carbon content is 0.17 ~ 0.22%, aluminium content is 1.1 ~ 1.2%, chromium content is 1.3 ~ 2.0%, p and s content is all less than 0.004% respectively, be respectively 4ppm and below 0.4ppm containing oxygen and hydrogen content, all the other are iron; (2) conventional forging or rolling is adopted to carry out plasticity hot-work to starting material; (3) hot worked for above-mentioned plasticity material is carried out machinery and be cold worked into gear; (4) said gear is heated to 930 ~ 950 DEG C, carburizing 210 ~ 300 minutes, carburizing backgear carbon contents is 1.0 ~ 1.2wt%, case depth 1.1 ~ 1.5mm; (5) thermal treatment of gear:

A, said gear is heated to 910 ~ 930 DEG C of insulations 80 ~ 120 minutes, carries out normalizing treatment;

B, said gear is heated to 870 ~ 880 DEG C of insulations 80 ~ 120 minutes, carries out austenitizing process, then within 60 ~ 200 minutes, carry out means of isothermal quenching 210 ~ 300 DEG C of insulations;

C, by said gear air cooling to room temperature ,-100 ~-70 DEG C keep 60 ~ 90 minutes;

D, said gear is heated to 180 ~ 240 DEG C of insulation 80 ~ 120min and carries out temper.

Ni, Mo or W element is added in 20CrAl component steel, and molybdenum content < 0.45wt%, nickel content < 0.45wt%, W content < 0.9wt%.

This gear manufacturing technology that the present invention relates to, very tiny by obtaining substructure size in the Ms point temperature isothermal quenching a little more than material, and there is not the bainite structure of carbide, it has the hardness of quenched martensite tissue and the toughness of quenched and tempered organization.

Embodiment

Adopt pure 20CrAl steel prepared by vacuum metling and vacuum consumable electroslag technology, the weight percent of its chemical composition is: carbon content is 0.18 ~ 0.21%, aluminium content is 1.1 ~ 1.2%, chromium content is 1.4 ~ 1.9%, p and s content is all less than 0.004% respectively, be respectively 4ppm and below 0.4ppm containing oxygen and hydrogen content, all the other are iron; Conventional forging or rolling is adopted to carry out plasticity hot-work to starting material; Hot worked for above-mentioned plasticity material is carried out machinery and is cold worked into gear; Said gear is heated to 930 ~ 940 DEG C, carburizing 220 ~ 300 minutes, carburizing backgear carbon contents is 1.1 ~ 1.2wt%, case depth 1.2 ~ 1.5mm; (5) thermal treatment of gear:

A, said gear is heated to 910 ~ 920 DEG C of insulations 80 ~ 110 minutes, carries out normalizing treatment;

B, said gear is heated to 870 ~ 880 DEG C of insulations 80 ~ 110 minutes, carries out austenitizing process, then within 80 ~ 180 minutes, carry out means of isothermal quenching 220 ~ 290 DEG C of insulations;

C, by said gear air cooling to room temperature ,-90 ~-70 DEG C keep 60 ~ 80 minutes;

D, said gear is heated to 190 ~ 230 DEG C of insulation 80 ~ 100min and carries out temper.

Ni, Mo or W element is added in 20CrAl component steel, and molybdenum content < 0.44wt%, nickel content < 0.44wt%, W content < 0.8wt%.

Method of the present invention compared with prior art tool has the following advantages: product of the present invention ensure that the through hardening performance of gear on the one hand, the heart portion after quenching that makes it obtains martensitic stucture, ensure that the top layer of gear is easy to obtain bainite structure on the other hand, and bainite should be carbide-free Bainite.This is conducive to the anti-rolling contact fatigue performance improving gear.This gear fertile material structural state is tempered martensite, and it maintains the conventional mechanical property such as pulling force and impact of tempered martensite.The rolling contact fatigue life that top layer of the present invention has a hard bainite structure gear is more than 3 times of traditional 42CrMo fatigue lifetime.Utilize friction wear testing machine to test the friction and wear behavior of this hard bainite structure, find that its friction and wear behavior is more than 3 times of traditional 42CrMo steel.In other words: obtain the High-performance gear that heart portion tempered martensite and surface are ultra-fine bainite structure, such gear in use dimensional stabilizing, under condition of high ground stress, its work-ing life improves more than 2 times than traditional 42CrMo steel gear of current widespread use fatigue lifetime.

Embodiment of the present invention does not form the restriction to the application's scope; within every spirit in the present invention's design and principle, any amendment that one of skill in the art can make, equivalent to replace and improvement etc. all should be included within protection scope of the present invention.

Claims

1. a gear manufacturing technology, it is characterized in that: the pure 20CrAl steel that (1) adopts vacuum metling and vacuum consumable electroslag technology to prepare, the weight percent of its chemical composition is: carbon content is 0.17 ~ 0.22%, aluminium content is 1.1 ~ 1.2%, chromium content is 1.3 ~ 2.0%, p and s content is all less than 0.004% respectively, be respectively 4ppm and below 0.4ppm containing oxygen and hydrogen content, all the other are iron; (2) conventional forging or rolling is adopted to carry out plasticity hot-work to starting material; (3) hot worked for above-mentioned plasticity material is carried out machinery and be cold worked into gear; (4) said gear is heated to 930 ~ 950 DEG C, carburizing 210 ~ 300 minutes, carburizing backgear carbon contents is 1.0 ~ 1.2wt%, case depth 1.1 ~ 1.5mm; (5) thermal treatment of gear:

2. a kind of gear manufacturing technology according to claim 1, it is characterized in that: in 20CrAl component steel, add Ni, Mo or W element, and molybdenum content < 0.45wt%, nickel content < 0.45wt%, W content < 0.9wt%.