CN104611525A

CN104611525A - Heating method for refining 30# steel austenite grains

Info

Publication number: CN104611525A
Application number: CN201510061207.4A
Authority: CN
Inventors: 亓海全; 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 steel 30# steel austenite grains. The heating method comprises the steps of (1) rapidly heating 30# steel to 1,000-1,100 DEG C at the heating speed of 5-1000 DEG C/second by adopting an electric contact heating method, a line-frequency induction heating method or an electric-induced fast heating method, and carrying out heat preservation for 1-5 seconds; (2) carrying out grading cooling and short-time heat preservation on the 30# steel obtained in the step (1), namely, rapidly cooling the 30# steel to 950-1,000 DEG C with a heat preservation time of 1-5 seconds, next rapidly cooling to 900-950 DEG C with a heat preservation time of 1-5 seconds, then rapidly cooling to 850-900 DEG C with a heat preservation time of 1-5 seconds, and finally rapidly cooling to 820-850 DEG C with a heat preservation time of 5-20 seconds, wherein the cooling speeds are all greater than or equal to 10 DEG C/s; and (3) quenching the 30# steel obtained in the step (2) or rapidly moving the 30# steel obtained in the step (2) to a pit furnace or a desktop furnace with a furnace box temperature of 820-850 DEG C for heat preservation for 5-60 minutes and then carrying out air cooling or quenched so that the austenitic grain size can reach 10-15 grades. The heating method disclosed by the invention is simple in process, complicated equipment does not need to be additionally arranged, the cost is low, the influence on a technological process of production is small, and the heating method can be applied to heat treatment of the 30# steel or heating process before heat processing.

Description

The heating means of a kind of refinement No. 30 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. 30 steel austenite crystals.

Background technology

No. 30 steel are widely used in manufacturing the parts such as axle class, pull bar, machine tool frame, usually use under normalizing or quality adjustment condition, have good toughness and weldability.When hot-work, modified or normalizing treatment, in order to obtain the performance requriementss such as good toughness and hardness, people wish obtain tiny austenite grain size when heating.Affect austenite grain size because have heating cycle and original structure etc., therefore the thermal treatment process of refinement No. 30 steel austenite grain sizes has thermomechanical treatment, rapid heating isothermal treatment for short time, reduces the means such as Heating temperature and circulating-heating quenching.But there is austenite not full and uniformization, the problem such as soaking time is long, grain refinement effect is limited in above-mentioned processing method.In view of this, the present invention proposes the heating process of a kind of refinement No. 30 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. 30 steel austenite crystals are provided.

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. 30 steel are quickly heated up to 1000 ~ 1100 DEG C, is incubated 1 ~ 5 second.

(2) step (1) gained No. 30 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 820 ~ 850 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. 30 steel being carried out quench or be quickly moved to fire box temperature is the cold or quenching of insulation 5 ~ 60 minutes laggard line spaces in the pit furnace of 820 ~ 850 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. 30 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. 30 steel pole materials of 10mm × 30mm quickly heat up to 1050 DEG C, are incubated 2 seconds.

(2) step (1) gained No. 30 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 4 seconds again, continue to be quickly cooled to 850 DEG C to be incubated 4 seconds, finally be quickly cooled to 820 DEG C to be incubated 10 seconds, speed of cooling is 20 DEG C/sec.

(3) step (2) gained No. 30 steel pole materials being quickly moved to fire box temperature is quenching after being incubated 10 minutes in the pit furnace of 820 DEG C, and autstenitic grain size is 15 grades.

embodiment 2:

(1) line-frequency induction heating is adopted, will Φno. 30 steel pole materials of 10mm × 30mm quickly heat up to 1020 DEG C, are incubated 2 seconds.

(2) step (1) gained No. 30 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 4 seconds again, continue to be quickly cooled to 850 DEG C to be incubated 4 seconds, finally be quickly cooled to 830 DEG C to be incubated 10 seconds, speed of cooling is 10 DEG C/sec.

(3) by No. 30 steel pole material quenchings of step (2) gained, autstenitic grain size is 14 grades.

embodiment 3:

(1) adopt electroluminescent rapid heating, rate of heating is 100 DEG C/sec, will Φno. 30 steel pole materials of 10mm × 30mm quickly heat up to 1050 DEG C, are incubated 2 seconds.

(2) step (1) gained No. 30 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 4 seconds again, continue to be quickly cooled to 850 DEG C to be incubated 4 seconds, finally be quickly cooled to 820 DEG C to be incubated 10 seconds, speed of cooling is 30 DEG C/sec.

Claims

1. heating means for refinement No. 30 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. 30 steel are quickly heated up to 1000 ~ 1100 DEG C, is incubated 1 ~ 5 second;

(2) step (1) gained No. 30 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 820 ~ 850 DEG C to be incubated 5 ~ 20 seconds, speed of cooling is all more than or equal to 10 DEG C/sec;