JPS58123857A - Steel product for pressure vessel with superior resistance to temper embrittlement - Google Patents

Abstract

PURPOSE:To enhance the resistance of steel products for a pressure vessel used at a high temp. to temper embrittlement by adding prescribed percentages of C, Si, Mn, P, S, La, Cr, Mo, etc. to Fe. CONSTITUTION:The titled steel products consist of, by weight, 0.05-0.3% C, <=0.5% Si, 0.02-2% Mn, <=0.02% P, <=0.02% S, 0.001-0.3% La, 0.5-5% Cr, 0.1-0.3% Mo and the balance Fe or further contains one or more among 0.001- 0.01% Ca, 0.01-0.2% Nb, 0.01-0.2% V, 0.01-0.2% Zr, 0.01-0.1% Ti, 0.0005- 0.005% B, 0.1-10% Ni and 0.1-0.6% Cu.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a material for pressure vessels that has excellent resistance to tempering embrittlement. Specifically, the present invention provides a material for pressure vessels that has excellent resistance to tempering embrittlement. It is related to Takuno, which significantly improves the resistance to tempering and brittleness in remote villages where pressure vessels are often used.

In recent years, with the progress of science and technology, reaction vessels and pressure vessels have tended to become larger and larger, and the environment in which they are used has become harsher. The material that appeals to you is a very +1! ! It's been a storm.

Among these controversial material properties, there is particular support for tempering brittleness due to the longer post-weld heat treatment (stress relief annealing) and higher operating temperatures associated with thicker materials. It's getting extremely strict, and it's difficult to take countermeasures! The reality is that.

In general, the tempering brittleness of low alloys is caused by - material processing or f
Long-term heat treatment after first contact (stress-relieving phosphorus dulling, #1#
When using static heat or Fx at high temperatures, K is
Pressure capacity: KP during slow cooling when making kechadau such as sushi, 8n
, 8bSAs, and 81 fathoms are thought to occur because impurity elements segregate at prior austenite grain boundaries and weaken the binding energy of the grain boundaries by 1.

Therefore, it is thought that K, which improves tempering resistance, is effective in reducing these impurity elements.
It is technically impossible to industrially produce a pipe with a reduced size, and even if it were technically possible, the manufacturing cost would be extremely high. .

The inventors of the present invention conducted research 1 to improve the fold-back brittleness using a bowl-shaped technique, and found new findings 1 as shown below.
Obtained.

In other words, the four most important causes of tI8 return embrittlement are the segregation of P to the grain boundaries, and the influence of other impurity elements is due to the fact that PKIIR is very small and PflLaf
This is thought to be because the addition of K stabilizes the formation of LaP. ) It has become clear that segregation can be suppressed.

The present invention was established based on the above-mentioned new knowledge, and specifically, after reducing the PtO in - to below 020 odor, Lm t of α001 to 0.30 -
Addition of 2% stabilization completely suppresses the grain boundary segregation of P and provides a steel material that is resistant to tempering brittleness.

First, the present inventors investigated the tempering embrittlement of CrMo@ and P,8
When we studied the relationship between the impurity element content of b, an, Am, and 8i fathom, we found that as shown above, it is clear that E is the most harmful to tempering embrittlement, During experiments in the production of water-resistant rust-prone steel, it was clearly shown that the addition of KLa suppressed the segregation of P. The present invention is mainly based on these two knowledges.

Therefore, the present invention! ! The gist of Violet is that the weight ratio is C: a, os~0.30%, 81:α50-9 lower, M
n: g, 02. ,．． 2.0%, P: 0.020
%9 below, 8:0020-month below, Lm: 0.001~
0.30%, Cr: 0.5-5.0%, Mo: 0]
~3.0%? The remainder consists of aFe and unavoidable impurities. ＃Mold.

Further, the second aspect of the present invention is that the weight ratio of C:
0.05-0.3O-18i: under 0.5OSu, M
n: 0.02-3.011 P: 0.02 (lJ
A lower, S: 0.02 OSW lower, La: 0, OO1~
03.0qb1 Cr: α5~5.0%, Mo: 0
．． Contains 1 to 3.011, history KS Ca @0001
0-0.010%, Nb: 0.01-020%, ■2001-0.20'%, Zr: 0.01-0.2
0%,'rt: 0.01~o,s vomit,B:
0.0005-3.011 s, Ni: o, l
o ~ 10.0%, Cu: α10 ~ 0.6016, the more traced l'! l; J, is characterized by containing all two types on the circumference, with the remainder consisting of t2Fe and unavoidable impurities.

2F: The main feature of the invention is that PtO in the steel
,020-month lower and then 0.001~0.3
P is stabilized by adding Laf of 0, and P
The point is to suppress the 12JIP analysis.

First, the present invention suppresses the grain boundary segregation of KP as described above, thereby improving the tempering resistance of steel materials. ! This effect is not degraded by the alloying elements or heat treatment, and does not have any negative effect on the mechanical properties and weldability.

Therefore, to clarify the reason for limiting the acid content of the steel of the present invention,
Next time Otsushi.

C: C light, less than 0.0596 is preferable to ensure the necessary strength, and if it exceeds 0.30 weldability,
Since the toughness would be impaired, it was limited to a range of 0.05 to 0.3.

8i: 8iIfX is an element necessary for deoxidation, or an element that reduces the deterioration of tempering brittleness, and aso Ig
If it exceeds l, the toughness I/c will also be adversely affected, so 0.501
Limited to late season.

Aln:Mu is an element necessary to obtain strength and toughness of 1. If it is less than 0.02%, it has no effect;
If you go overboard, you may actually damage the toughness, so
It was limited to 11 in the range of 002 to 2.0.

P: P segregates at grain boundaries and causes tempering brittleness.
L is also a cause of thickness 1, and it is desirable to reduce it as much as possible.However, due to the manufacturing cost, adding La to 9
# below 0, 02011 which is the upper limit of yJJJ1
It was fixed at 11.

8:8 is an impurity element that reduces toughness and is desirable to be as small as possible, but it is effective in preventing cracking! Since J is also present, it was limited to 0.020% # or lower.

La: La is one of the essential elements of the present invention. Does it have the effect of suppressing the segregation of P and improving the tempering resistance? If it is less than α001, the effect will be less than 0.30. Matsuka on the island is not economical, 0001-0.309
A range of 6 KISli was established.

('r: Cr Fiz corrosion resistance improvement degree, 411.
It is effective in improving hardness and tempering brittleness, but
If it is less than 0.5%, the effect is small and 5.0Sll-
There is a risk of compromising your n-ness if you exceed it, as ~s,
osomtsnc limited.

Mo: Mo is effective in improving hardenability, strength, and toughness, and is also effective in improving resistance to hydrogen attack, which is difficult in chemical reactors. If it is less than 3.0%, the effect will be small, and if it exceeds 3.0%, the toughness will be worse. elK limited.

C, 8iSMn, P, 8, La, Cr as above.

Although the limited composition of Mo is the basic composition of the present invention, the following limited components "s Nbs v-, Zr.

The effectiveness of the present invention can be improved by adding a 7t species or 2sN selected from 'rt, B, Nt, ('u).

Ca: Ca is effective in dispersing catfish-based inclusions, making them spheroidal, and improving the toughness of steel, but 0.00101
If it is less than 6, the effect JLL will be small, and if it is added more than 0.010%, Ca-based inclusions will increase and the weldability will be adversely affected.
Nb, V, Zr) FXMo has #t'uniform effect, but for the same reason as Mo], all α01~020%
It was set in the range of .

'l'j: 'l'j has the effect of improving strength, corrosion resistance, and hydrogen attack resistance, and when coexisting with B, has the effect of increasing BC)9yT performance, but 0.
If it is less than 01S, the effect is small, and if it exceeds αll51-, the toughness may deteriorate, so 0.01 to 0.1%.
・B: B is an element that improves hardenability, but it has a tensile effect of less than 00005% -fi3 (,0,
If it exceeds 0051, the toughness will deteriorate, so 010005~
o, oos- range i! LIMITED TO LK.

'Ni: Ni is effective in -improving corrosion resistance and toughness, but its effect is reduced to 0.116*.

It is not economical to add more than a small amount (, 10 @ whisper)
0.1G-10, @ l5e) range Kla was determined.

Cu:Ca lamp, improved corrosion resistance [0! Is there a J, O1O
If it is less than 0.6G11, the effect will be small, and if it exceeds 0.6G11, the hot workability will be impaired. A.K.
IIJl fixedtjt.

Next, the real IIh moga will be explained.

Prepared as each steel pipe sample shown in Table 1, Lm@
Stabilization of P by 21OK, improvement of #*return mtt clearly k*m [In the table, symbols 1.6.11 and 12 are comparison -, symbols 2.3.4.5, ? , 8.
9.10 is the present invention. All of these various samples were subjected to hot pressure grinding under normal conditions, and then subjected to quenching and tempering treatment (11001: '1 hour → water cooling, 650C 1 hour → water cooling). I did it.

Evaluation of resistance to tempering and brittleness was performed by conducting one isothermal embrittlement heat treatment at 500C for 300 hours, and measuring the difference in 5o anaerobic-brittle fracture [1jl transition temperature (FATT)] before and after the embrittlement treatment, ゛ ΔF A '
l' T t*Meter is performed from k, and the result is the second
Shown in the table. In this case, it can be said that it is a steel material with high tempering brittleness IIc, such as #1 of ΔFATT. As shown in this 5112 table, the 10ΔFATT of the present invention is below 15U# from the results of the lII mechanical property and kneeling test of the Solanaceae family,
It can be seen that the tempering brittleness resistance is significantly improved compared to comparative steel samples 1 and 6048.37CK.

In addition, the KP of comparative steel samples 11 and 12 is 00201s? If it exceeds the effect of adding K11La! J is less, so it softens and has less tempering brittleness than # of the present invention.

From the results above, it can be seen that the present invention can improve the resistance to deformation brittleness t! It is clear that a steel material with significantly superior IK can be obtained.

\1, \ In the above, the present invention was focused on improving the tempering brittleness of the material for pressure vessels, but the pressure S
It can also be applied to N-gai KJ for S, heat-resistant special tools used at high temperatures, and tools #.

Patent owner: 111 Wheel Steel Co., Ltd. Agent Patent Attorney Matsushita &# Patent Attorney Hitoshi Suzuki 129F)-

Claims (1)

[Claims] 1) Weight ratio: C: 0.05 to 3.01G, Si: 05
01G9 lower, Mn: 0.02-2.0chi, P: 00
2011i1-7, s: o, o2o, La
: 0.001~0.30'Ik, Cr:0.5~
A pressure vessel material containing 5.0% of Mo and 0.1 to 3.0% of Mo, with the remainder consisting of PE and unavoidable impurities. 2) C in gravity ratio: o, os ~ o, ao *, s
t: osos brightness, M n: (102゛~2.01
G, P: 0.02011M lower, 8: 00201
g# lower, La: 0.00] ~0.30 To-s
Cr: gs~s, os, No: 0.1~
Contains 3.011, *K%Ca: 0.001
0~0.01011, Nb: 0.01~0.20
s. V: 0.01-0.20, 7. r: Q, Oi
'-0,20%, Ti:oo1~o,1s, B:
o, oos = o, oos *SN + : o, t. ~1αos, Cu: α10~0.60 Contains one or more selected gold types, and the residual S is resistant to FC and inevitable impurities, and has excellent resistance to tempering and brittleness! !
Dexterous steel.