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Titanium and single additions of Cr, Mo, Ni, and Cu
I5 Titanium and single additions of Cr, Mo, Ni, and Cu T h e major alloying elements studied in Chapter 8 were deposited from electrodes formulated with raw materials which produced weld metals containing small amounts of microalloying elements. In this chapter, high purity weld metals containing the same major alloying elements were studied at 0.6 and 1.4%Mn, both with (code A and C) and without (code & and C,) the small addition of about 35 ppm T i shown in Chapter 10 to be capable of nucleating acicular ferrite in C-Mn weld metals. Other microalloying elements were held at very low levels (<5 ppm). Separate additions of 1, 1.5 and 2%Cr; 0.25,0.5 and 1%Mo; 1,2.2 and 3%Ni and 0.5,l and 1.6%Cu were made and tested as-welded only. Experimental techniques were as used in other stages of the project, except that the sides of the weld preparation were buttered to minimise compositional differences due to dilution. Some of these results have not been published before.
Low manganese (without titanium) Composition (Table 15.1) was well balanced in this, as in the other series. Carbon content was intentionally higher than that of welds in Chapter 8, averaging 0.075% compared with 0.046%; otherwise compositions were similar, apart from the lower levels of microalloying elements, and sulphur and phosphorus.
Mechanical properties As-welded tensile and Charpy properties are given in Table 15.2. Generally (Fig 15.1), molybdenum was the most potent strengthening element, followed by Cry C u and Ni. T h e first additions of all elements except chromium reduced 100 J Charpy temperature (Fig 15.2*). Subsequent additions (including manganese*) gave a sharp rise in transition temperature, except for In Fig. 15.2 and similar subsequent graphs, manganese in excess of the basic level (i.e. 0.6 or 1.4%) has been included in the graph.
362
Metallurgy of basic weld metal Table 15.1 Composition of singly alloyed weld metal with 0.6%Mn, without titanium Mn
Element, wt% C
Si
S
F
Alloy
Ti
N
0
Addition, %
None (A,)
0.073
0.64
0.34
0.008
0.007
0.0007
0.006
0.045
Cr, 1 1.5 2
0.070 0.074 0.076
0.65 0.58 0.64
0.35 0.25 0.28
0.008 0.008 0.008
0.010 0.010 0.008
1.OlCr 1.59 2.10
0.0005 0.0004 0.0008
0.008 0.009 0.008
0.050 0.050 0.049
Mo, 0.25 0.5 1
0.07U
0.66 0.66 0.63
0.31 0.34 0.30
0.006 0.007 0.008
0.008
0.073 0.075
0.008
0.24Mo 0.50 1.03
0.0005 0.0005 0.0005
0.008 0.008 0.008
0.043 0.045 0.044
Ni, 1 2.2 3
0.064 0.065 0.062
0.63 0.61 0.62
0.30 0.26 0.29
0.006 0.007 0.007
0.008 0.007 0.007
0.92Ni 2.14 3.01
0.0005 0.0005 0.0006
0.007 0.009 0.007
0.047 0.049 0.050
Cu, 0.5 1 1.6
0.068 0.065 0.064
0.62 0.62 0.64
0.28 0.30 0.32
0.008
0.007 0.009
0.50Cu 1.03 1.60
0.0005 0.0004 0.0004
0.007 0.007 0.006
0.048 0.052 0.050
0.007
0.007 0.007
0.008
~
Nore: unless otherwise stated, all welds contained -0.03%Ni, Cr, Cu, -0.005%Mo, <5 ppm Al, B, Nb, V.
Table 15.2 As-welded mechanical properties of singly alloyed welds with 0.6%Mn without titanium
Addition, %
None (&) Cr, 1 1.5 2 Mo, 0.25 0.5 1
Ni, 1 2.2 3 Cu, 0.5 1 1.5 Note: nd
-
Yield strength, N/mrnz 400 480 490 560 430 470 530 420 440 460 390 440 500
not determined.
Tensile strength, N/mmz 490 560 590 660 520 560 620 500 530 540 470 510 560
Elongation, %
32 22 19
nd 26 25 21 32 32 28 29 32 27
Reduction of area, %
76 75 72 69 79 75 73 77 76 77 77 79 73
Charpy transition, "C 100 J
28 J
-46
-70
-40 -22 -26 -61 -42 7
-68 -48 -40 -87 -76 -57
-63 -65 -65
-88 -95 -98
-63 -54 -24
-86 -87 -70
Titanium and single additions of Cr, Mo, Ni, and Cu
7ooc
a
I
0
1 ADDITIONAL ALLOYING
I
I
2 ELEMENT.
I
3 WtVo
I-
4
E
-
5400 -
A.W.
3
b
I
I
I
,
15.1 Influence of alloying elements on as-welded strength of high purity 0.6%Mn weld metal without titanium: a) Yield strength; b) Tensile strength.
nickel. At the 1 % level, molybdenum and manganese gave larger increases than copper and chromium. However, even with nickel, the level of 100 J at just below -60 "C, with a yield strength no better than 460 N/mm2, gave a combination of properties inferior to what is possible without major alloying but with 40 ppm Ti.
363
364
Metallurgy of basic weld metal
7 ;-80
-1001 0
i
IA.1
0
I
1
A.W. I
2
I
3
I
1
ADDITIONAL ALLOYING ELEMENT,wt.%
15.2 Influence of alloying elements on as-welded 100J Charpy transition temperature of high purity 0.6%Mn weld metal without titanium.
Low manganese (with titanium) T h e composition of the welds examined, given inTable 15.3, requires no comment. T h e titanium contents of 30-50 ppm were within the range where high acicular ferrite content and good toughness can be expected in C-l.4%Mn weld metals.
Mechanical properties T h e as-welded mechanical properties (Table 15.4 and Fig. 15.3) show that, as with the titanium-free 0.6%Mn deposits, molybdenum provided the greatest strengthening and nickel the least. T h e 100 J Charpy temperature (Fig. 15.4) started from a similar level to theTifree welds but showed some divergences. T h e beneficial effect of nickel was more marked and manganese proved to be beneficial up to a 0.8% increase (i.e. a manganese content of 1.4%).The harmful effects of molybdenum and copper were lessened and were not apparent until 1% had been added. However, chromium had a greater (harmful) influence than without titanium.
Titanium and single additions of Cr, Mo, Ni, and Cu Table 15.3 Composition of singly alloyed weld metal with 0.6%Mn and 35 ppm Ti Element, wt% C
Mn
Si
S
P
Alloy
Ti
N
O
Addition, % None (A)
0.073
0.64
0.35
0.005
0.004
0.0038
0.008
0.043
Cr, 1
0.077 0.078 0.078
0.66 0.62 0.64
0.32 0.26 0.28
0.008
0.007 0.008
0.010 0.005 0.007
1.03Cr 1.60 2.15
0.0034 0.0029 0.0042
0.008 0.010
0.046 0.047 0.048
0.069 0.073 0.072
0.68 0.66 0.66
0.33 0.34 0.32
0.006 0.007 0.007
0.008 0.007 0.007
0.24Mo 0.50 1.03
0.0036 0.0042 0.0040
0.007 0.007 0.008
0.040 0.043 0.041
Ni, 1 2.2 3
0.063 0.064 0.067
0.65 0.61 0.65
0.31 0.27 0.30
0.006 0.007 0.007
0.009 0.007 0.007
0.88Ni 2.17 3.03
0.0038 0.0032 0.0036
0.009 0.009 0.007
0.047 0.045 0.046
Cu, 0.5
0.063 0.064 0.066
0.64 0.63 0.67
0.30 0.30 0.37
0.008
0.008
0.007 0.006
0.007 0.008
0.53Cu 1.05 1.44
0.0043 0.0042 0.0051
0.007 0.006 0.006
0.045 0.046 0.045
1.5
2 Mo, 0.25 0.5 1
1
1.6
~
0.010
Nore: unless otherwise stated, all welds contained -0.03%Cr, Ni, Cu, -0.005%Mo, <5 pprn Al, B, Nb, V.
Table 15.4 As-welded mechanical properties of singly alloyed welds with 0.6%Mn and 35 ppm Ti
Addition, %
Yield strength, N/mm2
Tensile strength, N/mm'
Elongation, %
Reduction of area, %
Charpy transition, "C lOOJ
285
-45 -35 -8 8 -58 -48 -33 -6 3 -83 -85 -62 -58 -43
-70 -54 -35 -33 -82 -65 -66 -88 -113 -114 -94 -94 -77
~
None (A) Cr, 1 1.5 2 Mo, 0.25 0.5 1 Ni, 1 2.2 3 Cu, 0.5 1 1.5
400 490 510 600 440 480 560 420 460 480 420 430 520
490 560 600 680 520 560 640 500 540 560 500 500 570
33 21 17 18 25 27 24 32 28 29 29 27 29
78 78 74 69 79 78 76 77 79 78 79 77 75
365
366
Metallurgy of basic weld metal 8001
I
I
A
A.W.
a
I
I
0
1 ADDITIONAL ALLOYING
8001
'1 5400 3
0
I
m
, 1
ADDITIONAL ALLOYING
I
2 3 ELEMENT, w t % I
I
2
A.W.
I
3
ELEMENT, wt'/o
I
15.3 Influence of alloying elements on as-welded strength of high purity 0.6%Mn weld metal with 35ppm Ti: a) Yield strength; b) Tensile strength.
Titanium and single additions of Cr, Mo, Ni, and Cu
I
A.W.
I
1
-100 0
1 2 3 ADDITIONAL ALLOYING ELEMENT, wt.%
15.4 Influence of alloying elements on as-welded 100 J Charpy transition temperature of high purity 0.6Y'Mn weld metal with 35 pprn Ti.
Higher manganese (without titanium) The composition of the welds with no titanium and 1.4%Mn (Table 15.5) shows that the elements were held to the desired levels.
Mechanical properties Table 15.6 lists the as-welded mechanical properties, from which it appears that the higher manganese content increased strength and increased the strengthening effect of nickel (Fig. 15.5) but did not change the relative effects of the alloying elements. At the higher manganese level nickel ceased to improve toughness and the first additions of any alloying element no longer improved toughness - although they did not impair it (Fig. 15.6).The maximum additions of each element (aside from Mn and Ni) were equally detrimental.
Higher manganese (with titanium) The compositions of the welds examined are given in Table 15.7.
367
368
Metallurgy of basic weld metal Table 15.5 Composition of singly alloyed weld metal with 1.4%Mn, without titanium Element, wt% C
Mn
Si
P
S
Alloy
Ti
N
0
Addition, YO
None (C,)
0.078
1.43
0.26
0.006
0.006
0.0005
0.009
0.048
Cr, 1 1.5 2
0.080 0.075 0.076
1.48 1.48 1.44
0.28 0.28 0.28
0.007 0.007 0.007
0.006 0.005 0.007
1.07Cr 1.55 1.96
0.0005 0.0005 0.0005
0.009 0.009 0.008
0.044 0.047 0.048
Mo,0.25 0.5
0.076 0.076 0.076
1.53 1.45 1.41
0.28 0.25 0.24
0.008 0.008 0.008
0.006 0.006 0.006
0.25Mo 0.50 1.11
0.0005 0.0005 0.0005
0.008 0.008 0.008
0.044 0.046 0.045
0.073 0.071 0.073
1.39 1.48 1.43
0.28 0.26 0.24
0.007 0.007 0.008
0.007 0.012 0.006
0.95Ni 2.28 3.12
0.0005 0.0005 0.0005
0.008 0.009 0.008
0.045 0.046 0.046
0.080 0.075 0.074
1.47 1.41 1.36
0.24 0.24 0.22
0.007 0.006 0.008
0.007 0.008 0.010
0.55Cu 1.06 1.63
0.0005 0.0005 0.0005
0.010
0.046 0.048 0.048
1
Ni, 1 2.2 3
Cu, 0.5
1
1.6
~
0.009 0.011
Note: unless otherwise stated, all welds contained -0.03%Cr, Ni, Cu, -0.005%Mo, <5 ppm Al, B, Nb, V.
Table 15.6 As-welded mechanical properties of singly alloyed welds with 1.4%Mn, without titanium
Addition, %
Yield strength, Nlmm'
Tensile strength, Nlmmz
Elongation, %
Reduction of area, %
Charpy transition, "C lOOJ
~
~
28J ~
None (C,J Cr, 1 1.5 2 Mo, 0.25 0.5 1
400 570 590 640
490
32
76
-46
-70
660 690 730
69 70 69
-20 6 24
-70 -20
470 520 590
570 610 700
18 18 18 20 19 19
77 75 69
-24 -4 26
-61 -50 -50
Ni, 1 2.2 3 Cu, 0.5 1 1.5
470 510 570
550 600 670
26 22 16
78 75 71
-13 -20 -12
-48 -61 -64
450 490 560
540 570 640
27 25 23
79 75 71
-10 -4 23
-36 -48 -30
-55
Mechanical properties Titanium raised the general level of strength (Table 15.8) and increased still further the strengthening effect of nickel (Fig. 15.7), although the relative potency of the four elements was unchanged.
Titanium and single additions of Cr, Mo, Ni, and Cu
369
Table IS.7 Composition of singly alloyed weld metal with 1.4%Mn and 35 ppm Ti Mn
Element, wt% C
Si
S
P
Alloy
Ti
N
0
Addition, % ~~
~
None ( C )
0.074
1.46
0.28
0.008
0.008
0.0035
0.008
0.044
Cr, 1 1.5 2
0.079 0.073 0.078
1.56 1.53 1.48
0.30 0.29 0.29
0.007 0.007 0.007
0.01 1 0.010 0.010
1.03Cr 1.53 1.96
0.0027 0.0027 0.0028
0.010 0.008 0.008
0.043 0.044 0.044
Mo, 0.25
0.076 0.075 0.075
1.49 1.46 1.44
0.26 0.26 0.25
0.008 0.008 0.008
0.008 0.007 0.008
0.25Mo 0.50 1.07
0.0034 0.0031 0.0031
0.009 0.009 0.008
0.041 0.043 0.043
Ni, 1 2.2 3
0.076 0.068 0.075
1.48 1.46 1.46
0.25 0.27 0.26
0.008 0.008 0.008
0.006 0.007 0.006
0.95Ni 2.24 3.15
0.0033 0.0034 0.0032
0.008 0.008 0.007
0.042 0.044 0.042
Cu, 0.5
0.076 0.077 0.069
1.48 1.43 1.37
0.27 0.25 0.25
c1.007 0.007 0.007
0.008 0.008 0.009
0.53Cu
0.0022 0.00 19 0.0023
0.008 0.009 0.008
0.045 0.046 0.048
0.5 1
1
1.6
1.08 1.60
Note: unless otherwise stated, all welds contained -O.O3%Cr, Ni, Cu, -0.005%Mo, <5 ppm Al, B, Nb, V.
4
7001
L
I-
Y
I
5400
400
AW a
0
I 1
ADDITIONAL ALLOYlNG
I
I
2 3 ELEMENT. wtVo
a
0 1 ADDITIONAL ALLOYlNG
A.W 2 3 ELEMENT, wtY/n
15.5 Influence of alloying elements on as-welded strength of high purity 1.4%Mn weld metal without titanium: a) Yield strength: b) Tensile strength.
Titanium also improved the basic level of toughness (Fig. 15.8) considerably and, at the same time, it reduced the harmful effects of molybdenum and manganese, although not of the other elements. Nickel, in fact, was found to be definitely harmful in this context; the maximum addition of nearly 3% raised the 100 J Charpy temperature from nearly -70 "C to approximately -50 "C.
370
Metallurgy of basic weld metal Table 15.8 As-welded mechanical properties of singly alloyed welds with 1.4%Mn and 35 ppmTi Addition, %
Yield strength, N/rnm2
Tensile strength, N/mm2
Elongation, YO
Reduction of area, YO
Charpy transition, "C lOOJ
None (C) Cr, 1
28J
460
530
28
79
-68
-88
620 650 710
670 710 770
20 18 16
73 73 68
-58 -38 -6
-84 -79 -70
Mo, 0.25 0.5 1
560 600 650
600 640 720
25 21 20
77 74 71
-69 -56 -39
-86 -90 -85
Ni, 1
500 560 600
550 620 680
27 26 20
79 78 72
-62 -58 -49
-94 -102 -95
500 490 570
560 5 60 620
28 27 26
79 77 75
-57 -48 -15
-93 -85 -67
1.5 2
2.2 3
Cu, 0.5 1 1.5
-801 0
I
I
I
1 2 3 ADDITIONAL ALLOYING ELEMENT, w t . %
15.6 Influence of alloying elements on as-welded 100 J Charpy transition temperature of high purity 1.4%Mn weld metal without titanium.
Titanium and single additions of Cr, Mo, Ni, and Cu
371
8oor--.,oat la 0
I
a
1 ADDITIONAL AI-LOYING
AW I
'1 3400
I 3
2 3 ELEMENT, w t 7 o
, (CJ ,
0 1 ADDITIONAL ALLOYING
A.W.
2 3 ELEMENT, w t '/a
15.7 Influence of alloying elements on as-welded strength of high purity 1.4%Mn weld metal with 35 pprn Ti: a) Yield Strength; 6) Tensile strength.
2* o W a
3 I-
a
a -20 w
0
I W c I-
-40
m w
+ 7-60 > n e
2 -80
0
0
,
1 2 3 ADDITIONAL ALLOYING ELEMENT,wt. %
15.8 Influence of alloying elements on as-welded 100J Charpy transition temperature of high purity 1.4%Mn weld metal with 35 ppm Ti.
372
Metallurgy of basic weld metal
Discussion Although no supporting metallography was carried out, it is likely that -40 ppm T i has little effect on strength or toughness of alloyed pure weld metals unless they contain sufficient manganese and/or other alloying elements to give acicular ferrite in their microstructure. T h e significance of observations of acicular ferrite should be recognised. Acicular ferrite content is measured on as-deposited microstructure (which exists only to a limited extent in the regions from which test specimens were extracted). However, acicular ferrite in the asdeposited microstructure is a sure sign of its presence in the coarsegrained reheated structure. It is also a likely sign that the low temperature microstructure is refined and contains less harmful grain boundary cementite. For chromium alloying, which produces a bainitic microstructure, toughness in the 0.6%Mn deposits was independent of the presence of titanium. With 1.4%Mn, the transition temperatures of deposits with and without titanium converged as the amount of alloying was increased. Molybdenum, like manganese, promotes acicular ferrite, so that increasing alloying led to increased separation of toughness levels in deposits with and without titanium. Nickel produced an intermediate state of affairs. With 0.6%Mn, welds with titanium continued improving in toughness as nickel was increased up to almost 3%, whereas without titanium, adding more than 1%Ni gave little improvement. However, with 1.4%Mn, as little as 1%Ni reduced toughness, more so with titanium than without it. Overall, however, in weld metals giving a useful level of strength, titanium was helpful in achieving the best toughness and the purer weld metals were generally tougher than the similar, less pure compositions examined in Chapter 8. Copper, usually being an impurity in weld metals, was not examined in this way but may be regarded as relatively harmless if kept below 0.5%. For higher strength and good toughness, weld metals of the Mn-Ni-Mo type, i.e. containing the two more promising elements discussed above, were explored. The results of tests on this type of weld metal are presented in the next chapter.
Low manganese (without titanium) Composition (Table 15.1) was well balanced in this, as in the other series. Carbon content was intentionally higher than that of welds in Chapter 8, averaging 0.075% compared with 0.046%; otherwise compositions were similar, apart from the lower levels of microalloying elements, and sulphur and phosphorus.
Mechanical properties As-welded tensile and Charpy properties are given in Table 15.2. Generally (Fig 15.1), molybdenum was the most potent strengthening element, followed by Cry C u and Ni. T h e first additions of all elements except chromium reduced 100 J Charpy temperature (Fig 15.2*). Subsequent additions (including manganese*) gave a sharp rise in transition temperature, except for In Fig. 15.2 and similar subsequent graphs, manganese in excess of the basic level (i.e. 0.6 or 1.4%) has been included in the graph.
362
Metallurgy of basic weld metal Table 15.1 Composition of singly alloyed weld metal with 0.6%Mn, without titanium Mn
Element, wt% C
Si
S
F
Alloy
Ti
N
0
Addition, %
None (A,)
0.073
0.64
0.34
0.008
0.007
0.0007
0.006
0.045
Cr, 1 1.5 2
0.070 0.074 0.076
0.65 0.58 0.64
0.35 0.25 0.28
0.008 0.008 0.008
0.010 0.010 0.008
1.OlCr 1.59 2.10
0.0005 0.0004 0.0008
0.008 0.009 0.008
0.050 0.050 0.049
Mo, 0.25 0.5 1
0.07U
0.66 0.66 0.63
0.31 0.34 0.30
0.006 0.007 0.008
0.008
0.073 0.075
0.008
0.24Mo 0.50 1.03
0.0005 0.0005 0.0005
0.008 0.008 0.008
0.043 0.045 0.044
Ni, 1 2.2 3
0.064 0.065 0.062
0.63 0.61 0.62
0.30 0.26 0.29
0.006 0.007 0.007
0.008 0.007 0.007
0.92Ni 2.14 3.01
0.0005 0.0005 0.0006
0.007 0.009 0.007
0.047 0.049 0.050
Cu, 0.5 1 1.6
0.068 0.065 0.064
0.62 0.62 0.64
0.28 0.30 0.32
0.008
0.007 0.009
0.50Cu 1.03 1.60
0.0005 0.0004 0.0004
0.007 0.007 0.006
0.048 0.052 0.050
0.007
0.007 0.007
0.008
~
Nore: unless otherwise stated, all welds contained -0.03%Ni, Cr, Cu, -0.005%Mo, <5 ppm Al, B, Nb, V.
Table 15.2 As-welded mechanical properties of singly alloyed welds with 0.6%Mn without titanium
Addition, %
None (&) Cr, 1 1.5 2 Mo, 0.25 0.5 1
Ni, 1 2.2 3 Cu, 0.5 1 1.5 Note: nd
-
Yield strength, N/mrnz 400 480 490 560 430 470 530 420 440 460 390 440 500
not determined.
Tensile strength, N/mmz 490 560 590 660 520 560 620 500 530 540 470 510 560
Elongation, %
32 22 19
nd 26 25 21 32 32 28 29 32 27
Reduction of area, %
76 75 72 69 79 75 73 77 76 77 77 79 73
Charpy transition, "C 100 J
28 J
-46
-70
-40 -22 -26 -61 -42 7
-68 -48 -40 -87 -76 -57
-63 -65 -65
-88 -95 -98
-63 -54 -24
-86 -87 -70
Titanium and single additions of Cr, Mo, Ni, and Cu
7ooc
a
I
0
1 ADDITIONAL ALLOYING
I
I
2 ELEMENT.
I
3 WtVo
I-
4
E
-
5400 -
A.W.
3
b
I
I
I
,
15.1 Influence of alloying elements on as-welded strength of high purity 0.6%Mn weld metal without titanium: a) Yield strength; b) Tensile strength.
nickel. At the 1 % level, molybdenum and manganese gave larger increases than copper and chromium. However, even with nickel, the level of 100 J at just below -60 "C, with a yield strength no better than 460 N/mm2, gave a combination of properties inferior to what is possible without major alloying but with 40 ppm Ti.
363
364
Metallurgy of basic weld metal
7 ;-80
-1001 0
i
IA.1
0
I
1
A.W. I
2
I
3
I
1
ADDITIONAL ALLOYING ELEMENT,wt.%
15.2 Influence of alloying elements on as-welded 100J Charpy transition temperature of high purity 0.6%Mn weld metal without titanium.
Low manganese (with titanium) T h e composition of the welds examined, given inTable 15.3, requires no comment. T h e titanium contents of 30-50 ppm were within the range where high acicular ferrite content and good toughness can be expected in C-l.4%Mn weld metals.
Mechanical properties T h e as-welded mechanical properties (Table 15.4 and Fig. 15.3) show that, as with the titanium-free 0.6%Mn deposits, molybdenum provided the greatest strengthening and nickel the least. T h e 100 J Charpy temperature (Fig. 15.4) started from a similar level to theTifree welds but showed some divergences. T h e beneficial effect of nickel was more marked and manganese proved to be beneficial up to a 0.8% increase (i.e. a manganese content of 1.4%).The harmful effects of molybdenum and copper were lessened and were not apparent until 1% had been added. However, chromium had a greater (harmful) influence than without titanium.
Titanium and single additions of Cr, Mo, Ni, and Cu Table 15.3 Composition of singly alloyed weld metal with 0.6%Mn and 35 ppm Ti Element, wt% C
Mn
Si
S
P
Alloy
Ti
N
O
Addition, % None (A)
0.073
0.64
0.35
0.005
0.004
0.0038
0.008
0.043
Cr, 1
0.077 0.078 0.078
0.66 0.62 0.64
0.32 0.26 0.28
0.008
0.007 0.008
0.010 0.005 0.007
1.03Cr 1.60 2.15
0.0034 0.0029 0.0042
0.008 0.010
0.046 0.047 0.048
0.069 0.073 0.072
0.68 0.66 0.66
0.33 0.34 0.32
0.006 0.007 0.007
0.008 0.007 0.007
0.24Mo 0.50 1.03
0.0036 0.0042 0.0040
0.007 0.007 0.008
0.040 0.043 0.041
Ni, 1 2.2 3
0.063 0.064 0.067
0.65 0.61 0.65
0.31 0.27 0.30
0.006 0.007 0.007
0.009 0.007 0.007
0.88Ni 2.17 3.03
0.0038 0.0032 0.0036
0.009 0.009 0.007
0.047 0.045 0.046
Cu, 0.5
0.063 0.064 0.066
0.64 0.63 0.67
0.30 0.30 0.37
0.008
0.008
0.007 0.006
0.007 0.008
0.53Cu 1.05 1.44
0.0043 0.0042 0.0051
0.007 0.006 0.006
0.045 0.046 0.045
1.5
2 Mo, 0.25 0.5 1
1
1.6
~
0.010
Nore: unless otherwise stated, all welds contained -0.03%Cr, Ni, Cu, -0.005%Mo, <5 pprn Al, B, Nb, V.
Table 15.4 As-welded mechanical properties of singly alloyed welds with 0.6%Mn and 35 ppm Ti
Addition, %
Yield strength, N/mm2
Tensile strength, N/mm'
Elongation, %
Reduction of area, %
Charpy transition, "C lOOJ
285
-45 -35 -8 8 -58 -48 -33 -6 3 -83 -85 -62 -58 -43
-70 -54 -35 -33 -82 -65 -66 -88 -113 -114 -94 -94 -77
~
None (A) Cr, 1 1.5 2 Mo, 0.25 0.5 1 Ni, 1 2.2 3 Cu, 0.5 1 1.5
400 490 510 600 440 480 560 420 460 480 420 430 520
490 560 600 680 520 560 640 500 540 560 500 500 570
33 21 17 18 25 27 24 32 28 29 29 27 29
78 78 74 69 79 78 76 77 79 78 79 77 75
365
366
Metallurgy of basic weld metal 8001
I
I
A
A.W.
a
I
I
0
1 ADDITIONAL ALLOYING
8001
'1 5400 3
0
I
m
, 1
ADDITIONAL ALLOYING
I
2 3 ELEMENT, w t % I
I
2
A.W.
I
3
ELEMENT, wt'/o
I
15.3 Influence of alloying elements on as-welded strength of high purity 0.6%Mn weld metal with 35ppm Ti: a) Yield strength; b) Tensile strength.
Titanium and single additions of Cr, Mo, Ni, and Cu
I
A.W.
I
1
-100 0
1 2 3 ADDITIONAL ALLOYING ELEMENT, wt.%
15.4 Influence of alloying elements on as-welded 100 J Charpy transition temperature of high purity 0.6Y'Mn weld metal with 35 pprn Ti.
Higher manganese (without titanium) The composition of the welds with no titanium and 1.4%Mn (Table 15.5) shows that the elements were held to the desired levels.
Mechanical properties Table 15.6 lists the as-welded mechanical properties, from which it appears that the higher manganese content increased strength and increased the strengthening effect of nickel (Fig. 15.5) but did not change the relative effects of the alloying elements. At the higher manganese level nickel ceased to improve toughness and the first additions of any alloying element no longer improved toughness - although they did not impair it (Fig. 15.6).The maximum additions of each element (aside from Mn and Ni) were equally detrimental.
Higher manganese (with titanium) The compositions of the welds examined are given in Table 15.7.
367
368
Metallurgy of basic weld metal Table 15.5 Composition of singly alloyed weld metal with 1.4%Mn, without titanium Element, wt% C
Mn
Si
P
S
Alloy
Ti
N
0
Addition, YO
None (C,)
0.078
1.43
0.26
0.006
0.006
0.0005
0.009
0.048
Cr, 1 1.5 2
0.080 0.075 0.076
1.48 1.48 1.44
0.28 0.28 0.28
0.007 0.007 0.007
0.006 0.005 0.007
1.07Cr 1.55 1.96
0.0005 0.0005 0.0005
0.009 0.009 0.008
0.044 0.047 0.048
Mo,0.25 0.5
0.076 0.076 0.076
1.53 1.45 1.41
0.28 0.25 0.24
0.008 0.008 0.008
0.006 0.006 0.006
0.25Mo 0.50 1.11
0.0005 0.0005 0.0005
0.008 0.008 0.008
0.044 0.046 0.045
0.073 0.071 0.073
1.39 1.48 1.43
0.28 0.26 0.24
0.007 0.007 0.008
0.007 0.012 0.006
0.95Ni 2.28 3.12
0.0005 0.0005 0.0005
0.008 0.009 0.008
0.045 0.046 0.046
0.080 0.075 0.074
1.47 1.41 1.36
0.24 0.24 0.22
0.007 0.006 0.008
0.007 0.008 0.010
0.55Cu 1.06 1.63
0.0005 0.0005 0.0005
0.010
0.046 0.048 0.048
1
Ni, 1 2.2 3
Cu, 0.5
1
1.6
~
0.009 0.011
Note: unless otherwise stated, all welds contained -0.03%Cr, Ni, Cu, -0.005%Mo, <5 ppm Al, B, Nb, V.
Table 15.6 As-welded mechanical properties of singly alloyed welds with 1.4%Mn, without titanium
Addition, %
Yield strength, Nlmm'
Tensile strength, Nlmmz
Elongation, %
Reduction of area, %
Charpy transition, "C lOOJ
~
~
28J ~
None (C,J Cr, 1 1.5 2 Mo, 0.25 0.5 1
400 570 590 640
490
32
76
-46
-70
660 690 730
69 70 69
-20 6 24
-70 -20
470 520 590
570 610 700
18 18 18 20 19 19
77 75 69
-24 -4 26
-61 -50 -50
Ni, 1 2.2 3 Cu, 0.5 1 1.5
470 510 570
550 600 670
26 22 16
78 75 71
-13 -20 -12
-48 -61 -64
450 490 560
540 570 640
27 25 23
79 75 71
-10 -4 23
-36 -48 -30
-55
Mechanical properties Titanium raised the general level of strength (Table 15.8) and increased still further the strengthening effect of nickel (Fig. 15.7), although the relative potency of the four elements was unchanged.
Titanium and single additions of Cr, Mo, Ni, and Cu
369
Table IS.7 Composition of singly alloyed weld metal with 1.4%Mn and 35 ppm Ti Mn
Element, wt% C
Si
S
P
Alloy
Ti
N
0
Addition, % ~~
~
None ( C )
0.074
1.46
0.28
0.008
0.008
0.0035
0.008
0.044
Cr, 1 1.5 2
0.079 0.073 0.078
1.56 1.53 1.48
0.30 0.29 0.29
0.007 0.007 0.007
0.01 1 0.010 0.010
1.03Cr 1.53 1.96
0.0027 0.0027 0.0028
0.010 0.008 0.008
0.043 0.044 0.044
Mo, 0.25
0.076 0.075 0.075
1.49 1.46 1.44
0.26 0.26 0.25
0.008 0.008 0.008
0.008 0.007 0.008
0.25Mo 0.50 1.07
0.0034 0.0031 0.0031
0.009 0.009 0.008
0.041 0.043 0.043
Ni, 1 2.2 3
0.076 0.068 0.075
1.48 1.46 1.46
0.25 0.27 0.26
0.008 0.008 0.008
0.006 0.007 0.006
0.95Ni 2.24 3.15
0.0033 0.0034 0.0032
0.008 0.008 0.007
0.042 0.044 0.042
Cu, 0.5
0.076 0.077 0.069
1.48 1.43 1.37
0.27 0.25 0.25
c1.007 0.007 0.007
0.008 0.008 0.009
0.53Cu
0.0022 0.00 19 0.0023
0.008 0.009 0.008
0.045 0.046 0.048
0.5 1
1
1.6
1.08 1.60
Note: unless otherwise stated, all welds contained -O.O3%Cr, Ni, Cu, -0.005%Mo, <5 ppm Al, B, Nb, V.
4
7001
L
I-
Y
I
5400
400
AW a
0
I 1
ADDITIONAL ALLOYlNG
I
I
2 3 ELEMENT. wtVo
a
0 1 ADDITIONAL ALLOYlNG
A.W 2 3 ELEMENT, wtY/n
15.5 Influence of alloying elements on as-welded strength of high purity 1.4%Mn weld metal without titanium: a) Yield strength: b) Tensile strength.
Titanium also improved the basic level of toughness (Fig. 15.8) considerably and, at the same time, it reduced the harmful effects of molybdenum and manganese, although not of the other elements. Nickel, in fact, was found to be definitely harmful in this context; the maximum addition of nearly 3% raised the 100 J Charpy temperature from nearly -70 "C to approximately -50 "C.
370
Metallurgy of basic weld metal Table 15.8 As-welded mechanical properties of singly alloyed welds with 1.4%Mn and 35 ppmTi Addition, %
Yield strength, N/rnm2
Tensile strength, N/mm2
Elongation, YO
Reduction of area, YO
Charpy transition, "C lOOJ
None (C) Cr, 1
28J
460
530
28
79
-68
-88
620 650 710
670 710 770
20 18 16
73 73 68
-58 -38 -6
-84 -79 -70
Mo, 0.25 0.5 1
560 600 650
600 640 720
25 21 20
77 74 71
-69 -56 -39
-86 -90 -85
Ni, 1
500 560 600
550 620 680
27 26 20
79 78 72
-62 -58 -49
-94 -102 -95
500 490 570
560 5 60 620
28 27 26
79 77 75
-57 -48 -15
-93 -85 -67
1.5 2
2.2 3
Cu, 0.5 1 1.5
-801 0
I
I
I
1 2 3 ADDITIONAL ALLOYING ELEMENT, w t . %
15.6 Influence of alloying elements on as-welded 100 J Charpy transition temperature of high purity 1.4%Mn weld metal without titanium.
Titanium and single additions of Cr, Mo, Ni, and Cu
371
8oor--.,oat la 0
I
a
1 ADDITIONAL AI-LOYING
AW I
'1 3400
I 3
2 3 ELEMENT, w t 7 o
, (CJ ,
0 1 ADDITIONAL ALLOYING
A.W.
2 3 ELEMENT, w t '/a
15.7 Influence of alloying elements on as-welded strength of high purity 1.4%Mn weld metal with 35 pprn Ti: a) Yield Strength; 6) Tensile strength.
2* o W a
3 I-
a
a -20 w
0
I W c I-
-40
m w
+ 7-60 > n e
2 -80
0
0
,
1 2 3 ADDITIONAL ALLOYING ELEMENT,wt. %
15.8 Influence of alloying elements on as-welded 100J Charpy transition temperature of high purity 1.4%Mn weld metal with 35 ppm Ti.
372
Metallurgy of basic weld metal
Discussion Although no supporting metallography was carried out, it is likely that -40 ppm T i has little effect on strength or toughness of alloyed pure weld metals unless they contain sufficient manganese and/or other alloying elements to give acicular ferrite in their microstructure. T h e significance of observations of acicular ferrite should be recognised. Acicular ferrite content is measured on as-deposited microstructure (which exists only to a limited extent in the regions from which test specimens were extracted). However, acicular ferrite in the asdeposited microstructure is a sure sign of its presence in the coarsegrained reheated structure. It is also a likely sign that the low temperature microstructure is refined and contains less harmful grain boundary cementite. For chromium alloying, which produces a bainitic microstructure, toughness in the 0.6%Mn deposits was independent of the presence of titanium. With 1.4%Mn, the transition temperatures of deposits with and without titanium converged as the amount of alloying was increased. Molybdenum, like manganese, promotes acicular ferrite, so that increasing alloying led to increased separation of toughness levels in deposits with and without titanium. Nickel produced an intermediate state of affairs. With 0.6%Mn, welds with titanium continued improving in toughness as nickel was increased up to almost 3%, whereas without titanium, adding more than 1%Ni gave little improvement. However, with 1.4%Mn, as little as 1%Ni reduced toughness, more so with titanium than without it. Overall, however, in weld metals giving a useful level of strength, titanium was helpful in achieving the best toughness and the purer weld metals were generally tougher than the similar, less pure compositions examined in Chapter 8. Copper, usually being an impurity in weld metals, was not examined in this way but may be regarded as relatively harmless if kept below 0.5%. For higher strength and good toughness, weld metals of the Mn-Ni-Mo type, i.e. containing the two more promising elements discussed above, were explored. The results of tests on this type of weld metal are presented in the next chapter.