CN104611526A

CN104611526A - Heating method for refining 50# steel austenite crystal

Info

Publication number: CN104611526A
Application number: CN201510061246.4A
Authority: CN
Inventors: 亓海全; 焦慧彬; 周伍
Original assignee: Guilin University of Technology
Current assignee: Guilin University of Technology
Priority date: 2015-02-06
Filing date: 2015-02-06
Publication date: 2015-05-13

Abstract

The invention discloses a heating method for refining 50# steel austenite crystal. The heating method comprises the following steps: (1) rapidly heating the 50# steel to 1000-1050 degrees centigrade by adopting electrical contact heating, line-frequency induction heating or electrical rapid heating method, wherein the heating speed is 5-1000DEG C/second, and keeping the temperature for 1-5 seconds; (2) cooling the 50# steel by steps and keeping the temperature for a short time, namely rapidly cooling to 950-1000 degrees centigrade, and keeping the temperature for 1-5 seconds, and rapidly cooling to 900-950 degrees centigrade and keeping the temperature for 1-5 seconds, continuously rapidly cooling to 850-900 degrees centigrade and keeping the temperature for 1-5 seconds, and finally rapidly cooling to 800-830 degrees centigrade and keeping the temperature for 5-20 seconds, wherein the cooling speeds are all more than or equal to 10 degrees centigrade/second; (3) quenching the 50# steel obtained from the step (2) or rapidly moving the 50# steel to a pit furnace or a table furnace with the furnace box temperature of 800-830 degrees centigrade, keeping the temperature for 5-60 minutes, and performing air cooling or quenching, the austenitic grain size is grade 10-15. The heating method provided by the invention is simple in process without adding complex equipment and low in cost and has little effect on the production technology process, and can be used for the heat treatment of 50# steel and the heating process before hot working.

Description

The heating means of a kind of refinement No. 50 steel austenite crystals

Technical field

The present invention relates to iron and steel technical field of heat treatment, particularly the heating means of a kind of refinement No. 50 steel austenite crystals.

Background technology

No. 50 steel are middle carbon carbon constructional quality steels, have high intensity and hardness after quenching, are mainly used in parts such as manufacturing axle class, pull bar, drift.When quenching-tempering or normalizing treatment, in order to obtain the performance requriementss such as good toughness and hardness, it is desirable to obtain tiny austenite grain size when heating.Affect austenite grain size because have heating cycle and original structure etc., therefore the prior heat treatment process of refinement No. 50 steel austenite grain sizes has rapid heating isothermal treatment for short time, reduces the means such as Heating temperature or circulating-heating quenching.But the problem such as long the or grain refinement effect of full and uniformization, soaking time is not limited that above-mentioned processing method exists austenite.In view of this, the present invention proposes the heating means of a kind of refinement No. 50 steel austenite crystals.

Summary of the invention

The object of the invention is to overcome above-mentioned traditional technology Problems existing, to grow up theory based on austenite forming core, a kind of heating means of No. 50 steel austenite crystals are provided.

Concrete steps are:

(1) adopt Electricity Contact Heating or line-frequency induction heating, rate of heating is 5 ~ 1000 DEG C/sec, and No. 50 steel are quickly heated up to 1000 ~ 1100 DEG C, is incubated 1 ~ 5 second.

(2) step (1) gained No. 50 steel are carried out gradient cooling+isothermal treatment for short time, namely 950 ~ 1000 DEG C are first quickly cooled to be incubated 1 ~ 5 second, 900 ~ 950 DEG C are quickly cooled to be incubated 1 ~ 5 second again, continue to be quickly cooled to 850 ~ 900 DEG C to be incubated 1 ~ 5 second, finally be quickly cooled to 800 ~ 830 DEG C to be incubated 5 ~ 20 seconds, speed of cooling is all more than or equal to 10 DEG C/sec.

(3) step (2) gained No. 50 steel being carried out quench or be quickly moved to fire box temperature is the cold or oil quenching of insulation 5 ~ 60 minutes laggard line spaces in the pit furnace of 800 ~ 830 DEG C or desk stove, and autstenitic grain size can reach 10 ~ 15 grades.

The present invention has the following advantages compared with existing No. 50 steel heat treatment process:

(1) technique is simple, and without the need to increasing complex apparatus, cost is lower, little on technological process of production impact.

(2) autstenitic grain size after making prior heat treatment brings up to 10 ~ 15 grades by 8 ~ 10 grades.

Embodiment

embodiment 1:

(1) adopt Electricity Contact Heating, rate of heating is 100 DEG C/sec, will Φno. 50 steel pole materials of 10mm × 30mm quickly heat up to 1000 DEG C, are incubated 2 seconds.

(2) step (1) gained No. 50 steel pole materials are carried out gradient cooling+isothermal treatment for short time, namely 950 DEG C are first quickly cooled to be incubated 2 seconds, 900 DEG C are quickly cooled to be incubated 2 seconds again, continue to be quickly cooled to 850 DEG C to be incubated 4 seconds, finally be quickly cooled to 810 DEG C to be incubated 10 seconds, speed of cooling is 20 DEG C/sec.

(3) step (2) gained No. 50 steel pole materials being quickly moved to fire box temperature is be incubated 5 minutes in the pit furnace of 810 DEG C, and then oil quenching, autstenitic grain size is 15 grades.

embodiment 2:

(1) line-frequency induction heating is adopted, will Φno. 50 steel pole materials of 10mm × 30mm quickly heat up to 1000 DEG C, are incubated 2 seconds.

(2) step (1) gained No. 50 steel pole materials are carried out gradient cooling+isothermal treatment for short time, namely 950 DEG C are first quickly cooled to be incubated 2 seconds, 900 DEG C are quickly cooled to be incubated 2 seconds again, continue to be quickly cooled to 840 DEG C to be incubated 4 seconds, finally be quickly cooled to 810 DEG C to be incubated 10 seconds, speed of cooling is 20 DEG C/sec.

(3) step (2) gained No. 50 steel pole materials are carried out oil quenching, autstenitic grain size is 14 grades.

embodiment 31:

(1) adopt electroluminescent rapid-heating device, rate of heating is 100 DEG C/sec, will Φno. 50 steel pole materials of 10mm × 30mm quickly heat up to 1000 DEG C, are incubated 2 seconds.

(3) step (2) gained No. 50 steel pole materials being quickly moved to fire box temperature is be incubated 5 minutes in the pit furnace of 800 DEG C, and then oil quenching, autstenitic grain size is 15 grades.

Claims

1. heating means for refinement No. 50 steel austenite crystals, is characterized in that concrete steps are:

(1) adopt the heating of Electricity Contact Heating, line-frequency induction or electroluminescent rapid heating method, rate of heating is 5 ~ 1000 DEG C/sec, and No. 50 steel are quickly heated up to 1000 ~ 1100 DEG C, is incubated 1 ~ 5 second;

(2) step (1) gained No. 50 steel are carried out gradient cooling+isothermal treatment for short time, namely 950 ~ 1000 DEG C are first quickly cooled to be incubated 1 ~ 5 second, 900 ~ 950 DEG C are quickly cooled to be incubated 1 ~ 5 second again, continue to be quickly cooled to 850 ~ 900 DEG C to be incubated 1 ~ 5 second, finally be quickly cooled to 800 ~ 830 DEG C to be incubated 5 ~ 20 seconds, speed of cooling is all more than or equal to 10 DEG C/sec;