CN1269985C

CN1269985C - Steel for plastic injection moulding die with excellent mechanical workability

Info

Publication number: CN1269985C
Application number: CNB2004100618759A
Authority: CN
Inventors: 金大中
Original assignee: Doosan Heavy Industries and Construction Co Ltd
Current assignee: Doosan Heavy Industries and Construction Co Ltd
Priority date: 2003-06-26
Filing date: 2004-06-25
Publication date: 2006-08-16
Anticipated expiration: 2024-06-25
Also published as: CN1576382A; KR20050001663A

Abstract

The invention provides a steel for plastic ejection mold excellent in machinability and weld repairing characteristics. The steel for plastic ejection mold having outstanding machinability has an alloy composition comprising 0.10 to 0.30 wt.% of C, 0.40 to 0.70 wt.% of Si, 0.90 to 1.50 wt.% of Mn, 0.005 to 0.020 wt.% of S, 1.0 to 2.5 wt.% of Cr, 0.10 to 0.50 wt.% of Ni, 0.20 to 0.5 wt.% of Mo, 0.001 to 0.20 wt.% of V, and the balance being Fe.

Description

The injection-moulding plastic die steel of machinability excellence

Technical field

The present invention relates to as the die steel of injection-moulding plastic with the moulding stock use, relate in particular to the machinability excellence, can shorten the Production Time of mould, and can save the injection-moulding plastic die steel of Mold Making cost, machinability excellence.

Background technology

In the past,, mainly used S55C, SCM4 series, SNCM4 series as the injection-moulding plastic die steel, and their improvement type.

The exploitation trend of especially nearest injection-moulding plastic die steel emphasizes to shorten the Production Time of mould and the material that is equipped with according to purposes functional.And, the requirement that should improve Mold Making person and mould user accessibility is in the use increased.Therefore, in order to satisfy described requirement, must the new die steel kind of exploitation.

Here, so-called " mould accessibility in the use " is meant the cost of manufacture of saving mould, shortens necessary characteristic of Production Time.For example repair by welding excellence, machinability or machinability excellence, corrosion processing excellence, can obtain smooth machined surface as the minute surface etc.

In addition, recently the injection-moulding plastic mould is required precise treatment, complicated, maximize in, on the other hand, require shorter making delivery date.For this reason, an urgent demand is shortened process period, is shortened the repairing time etc.

But existing S55C, SCM4 series, SNCM4 series and their improvement type can not fully satisfy described requirement.

Summary of the invention

The objective of the invention is,, provide the injection-moulding plastic die steel of machinability and repair by welding excellence in order to satisfy described all requirements of relevant injection-moulding plastic die steel.

In order to realize described purpose, the injection-moulding plastic die steel of machinability excellence of the present invention, by in weight % (wt%), C:0.10～0.30wt%, Si:0.40～0.70wt%, Mn:0.90～1.50wt%, S:0.005～0.020wt%, Cr:1.0～2.5wt%, Ni:0.10～0.50wt%, Mo:0.20～0.5wt%, V:0.001～0.20wt%, all the other are alloy compositions formations of Fe.

Description of drawings

Fig. 1 is the graphic representation that the machinability (or machinability) of die steel of the present invention and existing die steel is compared in expression.

Embodiment

Below, to the effect of the basic alloying constituent that constitutes injection-moulding plastic die steel of the present invention and to the qualification reason of content range, be explained as follows.

1.C：0.10～0.30wt％

Carbon is that the hardness and the wear resistance institute that obtain to require after quenching and the tempering must indispensable compositions.In order to obtain the desired abundant intensity of injection-moulding plastic die steel, must there be carbon in the steel more than or equal to 0.10wt%.But, if the content of carbon surpasses 0.3wt%, promptly there is too much carbon, then machinability worsens, in large-scale bloom, because the segregation meeting produces etch pit.Therefore, must limit the content of carbon smaller or equal to 0.3wt%.

2.Si：0.40～0.70wt％

Si is the element that uses as reductor.If the amount of the Si in the steel is very little, the machinability variation after quenching and the tempering.For this reason, need make the inferior limit of Si content is 0.40wt%.

But, if surpassing 0.7wt%, content has too much silicon, under the use temperature of mould, toughness value reduces.For this reason, need limit it smaller or equal to 0.7wt%.

3.Mn：0.90～1.50wt％

Same with Si, Mn also is the element that uses as reductor.Aspect the hardness that Mn requires after the raising of guaranteeing hardenability and quenching, tempering is necessary.For the hardness that obtains to require, in steel, must contain Mn more than or equal to 0.9wt%.But, there is too much Mn if surpass 1.5wt%, then machinability descends, and causes crackle during quenching easily.For this reason, need limit it smaller or equal to 1.50wt%.

4.S：0.005～0.020wt％

S combines with Mn when solidifying and generates the MnS non-metallic inclusion.Therefore, by playing a role as the stress concentration position when the mechanical workout, or performance lubrication and play the effect that improves machinability.In order to give full play to such effect, must contain S more than or equal to 0.05wt%.But,, also be harmful to the processibility of electrodischarge machining(E.D.M.) if the excessive existence of S then when making large-scale bloom, because of the MnS skewness, not only increases the anisotropy of mechanical properties.For this reason, need limit it smaller or equal to 0.020wt%.

5.Cr：1.0～2.5wt％

Cr brings into play the effect of strengthening matrix, improving wear resistance by forming carbide.In addition, Cr is a very important element of guaranteeing hardenability with Mn.In order to obtain corresponding effects, must contain Cr more than or equal to 1.0wt%.But, there is too much Cr if surpass 2.5wt%, can cause machinability and corrosion-resistant processibility to descend.For this reason, need limit it smaller or equal to 2.5wt%.

6.Ni：0.10～0.50wt％

Ni brings into play the effect that improves hardenability by enlarging austenite region.But, if contain Ni too much, can reduce quench and tempering after machinability.For this reason, need limit it smaller or equal to 0.50wt%.0.10～0.50wt% preferably.

7.Mo：0.20～0.50wt％

Mo and Cr bring into play the effect of strengthening matrix, improving wear resistance by forming carbide equally.In addition, guaranteeing that it also is important composition aspect the hardenability.But the Mo that crosses volume can make high temperature toughness descend.For this reason, need limit it smaller or equal to 0.50wt%.0.20～0.50wt% preferably.

8.V：0.001～0.20wt％

V brings into play crystalline particle granular, the effect that improves toughness and intensity by forming trickle carbide.But, surpass 0.20wt% and have too much V, compare with the effect that improves toughness and intensity, more increased manufacturing cost.For this reason, need limit it smaller or equal to 0.20wt%.0.001～0.20wt% preferably.

Embodiment

For more in the past as the injection-moulding plastic mould with the die steel of the SNCM4 series of material widely used SCM4 series, improvement and the characteristic of die steel of the present invention, make these die steels by the production process of following explanation.

At first, have the steel of the alloy composition of table 1 record, use the vacuum refining furnace refining, cast 25 tons bloom with electric furnace fusion.Then, described bloom 1170 ℃ of heating, is forged with the forging ratio more than or equal to 4, make wide 1200mm, the angle section of thick 430mm.At this moment, the temperature of forging when finishing is 850 ℃, carries out normalizing 880 ℃ of heating after forging finishes and handles.

In order to give same cooling conditions, removing under the state of hammer scale during quenching, quenching and tempered thermal treatment.

Table 1

Embodiment	C	Si	Mn	S	Ni	Cr	Mo	V	Remarks
Embodiment	C	Si	Mn	S	Ni	Cr	Mo	V	Remarks	1	0.33	0.26	0.88	0.001	0.45	1.66	0.45	0.03	Existing steel
2	0.36	0.24	0.87	0.001	0.12	0.96	0.30	0.03		1	0.33	0.26	0.88	0.001	0.45	1.66	0.45	0.03
2	0.36	0.24	0.87	0.001	0.12	0.96	0.30	0.03	3	0.25	0.44	1.12	0.010	0.30	1.65	0.28	0.03	Steel of the present invention

Table 2

Distinguish	Quench and tempered condition	Surface hardness
Distinguish	Quench and tempered condition	Surface hardness	Embodiment	850 ℃ * 8 hours → 595 ℃ * 12 hours, air cooling	HS 41～43

Mechanical characteristics and machinability after mensuration quenching and the tempering.Heat treated target surface hardness is Shore hardness HS 39～45.

Carry out mechanical characteristic test at normal temperatures, the results are shown in table 3.

Table 3

Embodiment	Hardness (HS)	Yield strength (Kgf/mm ²)	Tensile strength (Kgf/mm ²)	Impact energy (Kgf-m)	Remarks
Embodiment	Hardness (HS)	Yield strength (Kgf/mm ²)	Tensile strength (Kgf/mm ²)	Impact energy (Kgf-m)	Remarks	1	40	81.0	92.2	8.6	Existing steel
2	43	97.1	106.0	7.2		1	40	81.0	92.2	8.6
2	43	97.1	106.0	7.2	3	39	76.3	92.6	11.2	Steel of the present invention

As shown in table 3, confirm that the steel of the SNCM4 series of die steel of the present invention and existing SCM4 series, improvement has the almost intensity and the toughness of peer-level.

In addition, the test-results of machinability shows at Fig. 1.

The equipment, instrument and the test conditions that are used for machinability (machinability) test are as follows.

Equipment: the M101 mechanical workout center (Machining Center) of Mitsubishi system.

Cutting tool: use slotting cutter (cobalt rapid tool steel (HISS) ENCC-EMS, 4 of cutting blades, end mill diameters 10mm that OSG company produces), cut existing die steel and die steel of the present invention, measure the wear loss (wear loss of the cutting blade of slotting cutter) of the instrument of this moment.

At this moment, 15 meters/minute of cutting speeds, transfer rate 95 mm/min, approach Ad:5mm/Rd:6mm, machining oil use water-soluble machining oil.

As shown in Figure 1, can confirm that with instrument the wear loss of existing die steel is compared, instrument is considerably less to the wear loss of die steel of the present invention.

The wear loss of instrument is few, the machinability of can giving counterevidence (machinability) excellence.

Like this, can know that it is identical that die steel of the present invention and existing die steel are compared mechanical properties, its machinability (machinability) is very excellent simultaneously.

The mould steel of die steel of the present invention and existing SCM4 series, improvement SNCM4 series has almost identical engineering properties, and it has excellent machining property simultaneously. Therefore, when using steel of the present invention to make plastic injection moulding mould, can obtain the effect of process time and the time of repairing of shortening mould. In addition, can shorten thus and make delivery date.

Claims

1. injection-moulding plastic die steel, it is characterized by, by in weight %, C:0.10%～0.30%, Si:0.40%～0.70%, Mn:0.90%～1.50%, S:0.005%～0.020%, Cr:1.0%～2.5%, Ni:0.10%～0.50%, Mo:0.20%～0.5%, V:0.001%～0.20%, all the other are alloy compositions formations of Fe.